Patent Publication Number: US-7589848-B2

Title: Apparatus for controlling image processing and a method for controlling image processing

Description:
This application is a divisional application of U.S. patent application Ser. No. 10/909,432, filed Aug. 3, 2004, which issued as U.S. Pat. No. 7,289,239 on Oct. 30, 2007, which is a divisional of U.S. patent application Ser. No. 08/745,152, filed Nov. 7, 1996, which issued as U.S. Pat. No. 6,813,038 on Nov. 2, 2004. 

   This application also claims the benefit of Japanese Patent Application No. 7-289779, filed Nov. 8, 1995, which is hereby incorporated by reference herein in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus for controlling image processing to control processing of image data transferred from a host computer, or the like. More particularly, the invention relates to an apparatus for controlling image processing that receives image data from a host computer, or the like, in the form of PDL data described using the page description language (hereinafter, referred to as the PDL), and also relates to a method of controlling the processing of images. 
   2. Related Background Art 
   Conventionally, the printing operation has been executed per printing job in a printing system, in which PDL data are received from a host computer, or the like, and images are processed and transferred for the image formation thereof. A unit set by a user in printing a document using an application program on a host computer is, in general, defined as a printing job. Each of such printing jobs transferred from the host computer has hitherto been processed for printing individually. 
   Since each printing job transferred from a host computer is processed for printing individually in the conventional image processing apparatus described above, the problems below are encountered. 
   (1) When each printing job is executed for printing in a printer, the printer is actuated and suspended per printing job. Therefore, if a printer takes a long time to be actuated and suspended, a waiting time between jobs becomes longer, leading to unfavorable performance. 
   (2) For a printer connected to an image processing apparatus, which is capable of printing on the right and reverse sides of one printing sheet, it is impossible to form a page contained in different jobs on the right and reverse sides of one sheet. 
   (3) For an image processing apparatus, which is provided with an N-in-1 printing function that enables the apparatus to print N-page images side by side on one sheet, it is impossible to form the pages contained in different jobs on one sheet. 
   (4) For a printer connected to an image processing apparatus, which is provided with a sort printing function to sort and to print jobs on plural pages or plural sheets, partly or per job, it is impossible to sort and to print pages contained in different jobs together. 
   (5) For a printer connected to an image processing apparatus, which is provided with a sort-staple printing function where stapling is made per sorted sheet after a sort printing, it is impossible to execute the sort-staple printing for pages included in different jobs together. 
   (6) Also, when a user produces one document by dividing it into a plurality of files, there is a need for the user to sort each of them manually, if each document is printed individually. 
   (7) Further, when a user produces one document using a plurality of applications, there is a need for the user to sort them manually, when the documents are each printed individually. If the user produces the first and third pages using an application for producing documents, and then, produces the second and fourth pages using another application for producing graphics, or the like, the user should manually sort them after printing, for example. 
   Furthermore, when one document is divided and produced by a plurality of users responsible for the divided portions, respectively, it is necessary for the users to print each of them individually and to sort them manually. 
   SUMMARY OF THE INVENTION 
   The present invention is designed in consideration of the situations described above. It is an object of the invention to provide an apparatus for controlling image processing capable of applying the various processes, which should be executed per unit of job in the conventional art, to a plurality of printing jobs, as a whole, by joining a plurality of printing jobs that have been transferred from a computer on the printer or server side, as well as to provide a method for controlling image processing. 
   In order to achieve the objectives described in the preceding paragraph, the apparatus for controlling image processing of the present invention and the method thereof are arranged to receive printing jobs, to hold the printing jobs thus received, to join a plurality of printing jobs in a spooler together as one printing job, to control a printer so that the printing jobs thus joined can be transferred to the printer side to form images, and to execute image processing for the joined printing jobs as one printing job having a plurality of printing jobs thus put together. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view which illustrates a job joint in which several jobs are joined together. 
       FIG. 2  is a block diagram which shows an image processing apparatus in accordance with a first embodiment of the present invention. 
       FIG. 3  is a view which schematically shows the structure of an image forming apparatus. 
       FIGS. 4A ,  4 B,  4 C,  4 D,  4 E and  4 F are views which illustrate the page description language (PDL). 
       FIG. 5  is a view which illustrates printing jobs. 
       FIGS. 6A and 6B  are views which illustrate printing on the right and reverse sides of a sheet. 
       FIGS. 7A and 7B  are views which illustrate duplex printing. 
       FIGS. 8A and 8B  are views which illustrate a four-in-one printing. 
       FIGS. 9A and 9B  are views which illustrate a sort-printing. 
       FIG. 10  is a view which shows the structure of a queue in accordance with the first embodiment. 
       FIGS. 11A ,  11 B,  11 C,  11 D,  11 E,  11 F,  11 G and  11 H are views which illustrate the job description language (JDL). 
       FIG. 12  is a flowchart ( 1 ) used for the image processing apparatus in accordance with the first embodiment. 
       FIG. 13  is a flowchart ( 2 ) for the image processing apparatus in accordance with the first embodiment. 
       FIG. 14  is a view which shows the structure of a queue in accordance with a second embodiment of the present invention. 
       FIG. 15  is a flowchart for an image processing apparatus in accordance with the second embodiment. 
       FIG. 16  is a view which shows a printing format in accordance with the second embodiment. 
       FIG. 17  is a block diagram which shows an image processing apparatus in accordance with a third embodiment of the present invention. 
       FIG. 18  is a view which shows the structure of a queue in accordance with the third embodiment. 
       FIGS. 19A and 19B  are views which illustrate an operational screen in accordance with the third embodiment. 
       FIG. 20  is a flowchart used for the image processing apparatus in accordance with the third embodiment. 
       FIG. 21  is a view which shows the structure of a queue in accordance with a fourth embodiment of the present invention. 
       FIGS. 22A and 22B  are views which illustrate an operational screen in accordance with the fourth embodiment. 
       FIG. 23  is a view which shows a queue in accordance with a fifth embodiment of the present invention. 
       FIG. 24  is a flowchart used for the image processing apparatus in accordance with the fifth embodiment. 
       FIG. 25  is a view which schematically shows a case wherein a program is provided for an apparatus. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
     FIG. 2  is a block diagram which shows an image formation system comprising an image processing apparatus  3  and an image forming apparatus  1 , which deal with the color page description language (PDL) in accordance with a first embodiment of the present invention. 
   As shown in  FIG. 2 , host computers  2 - 1 ,  2 - 2 , and  2 - 3 , and an image processing apparatus  3 , are connected through a network  4 . The PDL data that have been transferred from the host computers through the network  4  and an external interface circuit  5  are held once on a spooler area  8 - 1  on a hard disk  8  by means of a CPU  6 . Then, the PDL data read out from the spooler area  8 - 1  are developed into raster image data, which are written on a full-page image memory  10 - 1  in a RAM  10 . The image data thus developed are read out from the full-page image memory  10 - 1  and transferred to an image forming apparatus  1  by way of a printer interface circuit  11  for the formation of images. The program area  8 - 2  on the hard disk  8  is used for holding a program. This program is transferred to a work memory region  10 - 2  in the RAM  10  for the execution of the program. A part of the work memory region  10 - 2  and the work memory region  8 - 3  on the hard disk  8  are also used as provisional work regions. A printer communication unit  9  is used for communicating with the image forming apparatus  1 . Also, reference numeral  7  designates a CPU bus to connect them. 
   In accordance with the present embodiment, the image memory  10 - 1  comprises a total of twenty-four bits, eight bits each of RGB (Red, Green, and Blue) per pixel, having a capacity of one page portion in terms of an A-3 size. When printing in an A-4 size, it can hold a two-page portion. 
   In accordance with the present embodiment, the image forming apparatus  1  is a full-color electro-photographic copying machine, and performs the image formation in accordance with raster type image data  12  of twenty-four bits, eight bits each of RGB per pixel, which are transferred from an image processing apparatus. Since, however, the image formation is made by use of four color toners of YMCK (Yellow, Magenta, Cyan, and Black), the RGB should be converted to the YMCK in the interior of the image forming apparatus  1 . 
     FIG. 3  is a block diagram, which schematically illustrates the structure of the full-color electro-photographic copying machine serving as the image forming apparatus  1 . A reference  31  designates an automatic document feeder, which is called a DF (Document Feeder). An automatic DF is used for many copying machines currently available on the market. Therefore, a detailed description thereof will be omitted. This device is one in which a plurality of documents are stacked on it, and each one of them is being carried to a reading position thereof. A document placed on the reading position thereof (not shown) is read by image reader  32  comprising an optical system, a color CCD, and the like (not shown), and transformed into RGB image data. Then, through a switching  45 , such data are converted to YMCK by means of an image processor  33 . After that, the data are transferred to a laser driver  34 . Meanwhile, the image data  12 , which are transferred from the image processing apparatus  3 , are also converted to YMCK data by the image processor  33  through the switching  45 , and, after that, transferred to the laser driver  34 . When the image forming apparatus  1  functions as a copying machine, the image data  46  are selected by the switching unit  45  among those from the image reader  32 . When functioning as a printer, the image data  12  are selected by the switching  45  among those being transferred from the image processing apparatus  3 . The image data transferred from the image processor  33  are transformed into a laser beam in the laser driver  34 , in order to form latent images on a photosensitive drum  35 . A sheet, to form images on, is being fed from an upper cassette  37  or a lower cassette  39 , and wound around a transfer drum  36 . Toner adheres to the latent images on the photosensitive drum by means of a developing device (not shown) to become visible ones, which are transferred onto the sheet by means of the transfer unit  36 . The formation of latent images, development, and transfer are repeated four times by rotating the transfer drum four times per YMCK per sheet, so as to transfer YMCK toners onto the sheet. The sheet having the transferred toners is carried to a fixing device  40  where toners are fused and fixed to form full-color images. The sheet thus fixed is carried to a staple sorter  42  at the time of ordinary printing (the same is applicable to ordinary copying. Hereinafter, the same), and usually, delivered to the uppermost tray  44 - 1 . 
   On the other hand, when printing is made on the right surface of a double printing, a sheet that has passed the fixing device  40  is carried to a reversing unit  41 . Then, its forwarding direction is reversed by the reversing unit  41  to enter a duplex tray  38 . At this juncture, the images on the right side are placed on the upper side of a sheet. Then, printing is made on the reverse side of the sheet fed from the duplex tray in the same path as in the ordinary printing, and delivered. 
   Further, when an ordinary sort printing is made on a plurality of pages on plural sheets, each sheet transferred to a staple sorter  42  is output by distributing them to each of the delivery sheet trays  44 - 1 ,  44 - 2 , and  44 - 3 . In other words, the output of one sheet having plural pages is stacked on each of the sheet delivery trays. 
   Also, when a group sort printing is made on a plurality of pages on plural sheets, each of the pages transferred to the staple sorter  42  is output by distributing it to each of the sheet delivery trays  44 - 1 ,  44 - 2 , and  44 - 3 . In other words, the output of plural sheets is stacked on each of the sheet delivery trays per page. 
   Here, the ordinary sort printing and group sort printing are referred to as a sort printing, altogether. Also, since  FIG. 3  is a schematic view, only three sheet delivery trays are represented. In practice, however, an arrangement is made to form this structure by use of ten or twenty-five trays. 
   Also, to the staple sorter  42 , a stapler  43  belongs, which functions to staple sheets stacked on each of the sheet delivery trays. Usually, this function is applied together with the sort printing function. Therefore, it is called the sort-staple printing. For example, when this function is combined with a sort-printing, a stapling is usually executed per output of one sheet of plural pages, and then, plural sheets thereof are obtained. 
     FIGS. 4A ,  4 B,  4 C,  4 D,  4 E and  4 F are views which illustrate the PDL data. The PDL (Page Description Language) represented by a language, Post Script (registered trademark) of ADOBE, Inc., is, as shown in  FIG. 4A , the language to describe images per image on one page by combining elements of (i) images described through character codes, (ii) images described through graphic codes, and (iii) images described through raster image data, among some others. 
     FIG. 4B  shows the example of a description through character codes. A reference mark L 100  designates a description to specify the character colors. The description in parentheses represents brightness of red, green, and blue, in that order. The minimum is 0.0 and the maximum is 1.0. Reference mark L 100  designates that the characters are colors in black. Then, a reference mark L 101  designates that a character string “IC” is assigned to variable String 1 . Then, a reference mark L 102  designates that the first and second parameters indicate the x coordinate and y coordinate at the starting position thereof on a sheet, on which the layout of a character string is designed, and that the third parameter indicates intervals between the characters, while the fifth parameter indicates the character string that should be designed for the intended layout. In other words, reference mark L 102  designates a character string “IC” beginning at coordinates (0, 0, 0, 0) in a size of 0.3, at an interval of 0.1, for the intended layout. 
     FIG. 4C  shows the example of a description through graphic codes. A reference mark L 103  designates the line colors, as in L 100 . Here, the color red is specified. Then, a reference mark L 104  designates an instruction to draw lines whose first and second parameters designate the starting X and Y coordinates and the third and fourth parameters designate the terminating X and Y coordinates thereof, and a fifth parameter designates the thickness of the line. 
     FIG. 4D  shows the example of a description through raster image data. A reference mark L 105  designates that raster image data are assigned to a variable image 1 . Here, the first parameter indicates the image type of the raster image and the numbers of color components. The second parameter indicates the bit numbers of one color component. The third and fourth parameters indicate the image size of a raster image in the direction x and direction y. The fifth parameter and on indicate the raster image data. The numbers of raster image data are the product of the numbers of color components that form one pixel, and the image size in the direction x and direction y. For reference mark L 105 , the RGB image is formed by three color components (Red, Green, and Blue). Therefore, the numbers of raster image data are 75 (=3×5×5). 
     FIG. 4E  shows a state where the raster image data are developed by interpreting the image descriptions represented in  FIGS. 4B ,  4 C, and  4 D within one range. References marks R 100 , R 101 , and R 102  designate the developments of the PDL data shown in  FIGS. 4B ,  4 C, and  4 D, respectively. Actually, these raster image data are developed within the full-page image memory  10 - 1  per RGB color component. For example, for the R 100  portion, 0 is written for each of them in each of the RGB memories, while for the R 101  portion, 255, 0, 0 are written, respectively. 
   The PDL data transferred from the host computer  2  are developed to the raster image likewise, and written on the image memory  10 - 1 . 
   In accordance with the present embodiment, it is ready for the PDL to make the descriptions of various modes when executing a printing job.  FIG. 4F  shows the example of such descriptions of various modes. A reference mark L 107  designates an instruction to print this job in the four-in-one mode that will be described later; likewise, reference marks L 108 , L 019 , and L 110 , designate instructions to print this job in the duplex mode, sort mode, and staple mode, respectively. These modes will be described later. Also, reference mark L 111  designates an instruction to print four sheets per page included in this job. The four-in-one mode will be described later. 
     FIG. 5  is a view which illustrates printing jobs. The job A is a printing job transferred from the user a (host computer a). This job is formed by three pages  41 - 1  to  41 - 3 . In  FIG. 5 , a reference mark P. 1  designates a first page. Likewise, the job B is a two-page job from the user  2 . The job C is a one-page job from the user a. 
     FIG. 1  is a view which illustrates a job joint. The “addition-joint” job X is a job to join the job A, job B, and job C in  FIG. 5 , additionally, in that order. In other words, the three pages of the job A are the first page to third page of the joint job X; likewise, the job B, the fourth and fifth pages; and the job C, the sixth page. The “insertion-joint” job Y is a job to insert the job C in  FIG. 5  between the second and third pages of the job A and join them together. The joint job Y is formed by inserting another job into one job, but the present invention is not necessarily limited thereto. A case where each of the pages of two or more jobs is joined at random, similar to a nest, is also included. The “composition-joint” job Z is a joint job where the job B and job C in  FIG. 5  are composed. In other words, the first page of the job B and the first page of the job C are overlaid for formation on one sheet. 
     FIGS. 6A and 6B  are views which illustrate a continuous printing.  FIG. 6A  represents a state where printing is continuously executed without any job joint. At first, a printer is actuated to print the job A. When the printer is ready, the feeding of the first page begins. Then, an image formation is executed, and the sheet is delivered. Each of the pages for one job is given a pipe line process (an assembly-line process), thus executing the sheet feeding, formation, and sheet delivery in succession. In other words, in parallel with the sheet delivery of the first page, the formation of the second page, and the sheet feeding of the third page are performed. When the third page, that is, the last page of the job A, is delivered, the printer enters its suspension process. After such a process is completed, the printer comes to a stop. The job B printing takes place after the printer is actuated anew, after the complete termination of the job A printing. 
   On the other hand,  FIG. 6B  represents the state where a printing is continuously executed by the application of the “addition-joint” job X when jobs are joined. The first three pages (job A) of the job X are printed in the same manner as shown in  FIG. 6A , but, in the job joint, the next two pages (job B) and one page (job C) to follow are also formed in succession, without any suspension of the printer between jobs A and B, and between jobs B and C. Therefore, as is clear from  FIGS. 6A and 6B , the time required for printing for the jobs A, B, and C becomes much shorter when the job joint is executed. 
     FIGS. 7A and 7B  are views which illustrate a duplex printing.  FIG. 7A  represents a state where a duplex printing is executed without any job joint. At first, the first and second pages of the job A are formed on the right and reverse sides of one sheet. Then, the third page of the job A is printed on the right side of the second sheet. However, since there is only the third page for the job A, the second sheet is delivered without any prints on the reverse side thereof. Likewise, the job C is executed to print on both sides using one sheet each, respectively. 
   On the other hand,  FIG. 7B  represents a state where a duplex printing is executed by the application of the addition-joint job X when a job joint is performed. As in the case shown in  FIG. 7A , the first two pages of the job X are formed on the right and reverse sides of the first sheet. Then, the third page of the job A, which is the third page of the job X and the first page of the job B, which is the fourth page of the job X, are formed on the right and reverse sides of the second sheet. At the same time, the second page of the job B and the first page of the job C are formed on the right and reverse sides of the third sheet. In this way, whereas four sheets are needed for printing shown in  FIG. 7A , only three sheets are needed for the execution of printing shown in  FIG. 7B . Also, if the jobs A, B, and C are prepared for the production of one document from the beginning, it is not desirable to allow blank portions to enter between them, as shown in  FIG. 7A . 
     FIGS. 8A and 8B  are views which illustrate a four-in-one printing.  FIG. 8A  represents a state of four-in-one printing without any execution of a job joint. The four-in-one printing means a function to print images of four sheets on one sheet, side by side, by means of image contraction, and such an arrangement of contracted images thereon. The number of images for the side by side arrangement is not necessarily four, but two or eight may printable, likewise. These are collectively called an N-in-1 printing function. For the four-in-one printing, the first to third pages of the job A are formed on the first sheet side by side. Since there are only three pages for the job A, the fourth area of the first sheet is formed in blank without any images. Likewise, the four-in-one printing is executed for the job B and job C using one sheet, respectively. 
   On the other hand,  FIG. 8B  represents a stage where the four-in-one printing is executed by the application of the addition-joint job X when a job joint is performed. The first three pages (job A) of the job X are placed on the first sheet side by side. Then, the first page of the job B, which is the fourth page of the job X, is placed side by side on the fourth area on the first sheet. Likewise, the second page of the job B and the first page of the job C are formed on the second sheet side by side. In this way, whereas three sheets are needed for the performance shown in  FIG. 8A , only two sheets are needed for the performance shown in  FIG. 8B . Also, if the jobs A, B and C are prepared for the formation of one document from the beginning, it is not desirable to allow black portions to enter between them, as shown in  FIG. 8A . 
     FIGS. 9A and 9B  are views which illustrate a sort printing.  FIG. 9A  represents a state of a sort printing without the execution of any job joint. At first, two sheets of three pages of the job A are sort-printed, and each of the sheets of the job A is delivered to each of the sheet delivery trays on the staple sorter  42  one by one. The user picks them up, and then, two sheets of two pages of the job B and two sheets of one page of the job C are delivered in the same manner. Therefore, the user should manually sort each of the jobs, each page of which has been delivered one by one if the jobs A, B and C are prepared for one document from the beginning. This arrangement requires a considerable amount of work, particularly, when there is a need for the user to sort each page of each job in the form of a nest. Also, if stapling is needed per sorted portion, it is necessary for the user to sort each of the pages manually, and then, to staple them manually. 
   On the other hand,  FIG. 9B  represents a state of a sort printing of an addition-joint job X when the job joint is performed. As in  FIG. 9A , the first two sheets of three pages of the job X are sort-printed. Each one of them is delivered to each of the sheet delivery trays on the staple sorter one by one. Then, two sheets of the job B, which are the fourth and fifth pages of the job X, are sort-printed, and delivered onto the pages of the job A. Likewise, two pages of the job C are delivered onto those of the job B. As a result, six pages of the job X are delivered onto each of the sheet delivery trays one by one. This has been a description regarding a case of the addition-joint job X. However, also, in a case of an insertion-joint job Y, sheets are delivered likewise onto each of the sheet delivery trays in order of being joined as in the addition-joint job. Therefore, it is unnecessary for the user to sort them manually. Likewise, when stapling is required for each sorted portion, the stapler  43  staples each portion automatically. 
   Here, a description has been made of a case where an ordinary sorting is performed, but the same is applicable to a case where sorting is performed by the application of a group sort, instead of the ordinary sort. 
   As described above, each of the continuous printing, duplex printing, N-in-1 printing, sort printing, and staple-sort printing has been explained individually, with respect to the job joint. It is, of course, possible to combine each of these functions and to apply them to a job joint. For example, a job joint is possible in such a manner that, while executing the four-in-one, the duplex printing is performed with the subsequent staple sorting. 
     FIG. 10  is a view which illustrates the state of a job joint being executed. The image processing apparatus of the first embodiment holds jobs received from a host computer in the spooler  8 - 1  on a hard disk. Two kinds of queues are used to hold them. As shown in  FIG. 10 , one is called a printing queue where jobs are arranged in line in order of those being received in the queue. It is devised to execute printing beginning with a job at the head of the queue. The other is called a holding queue where, although jobs are arranged in line in order of those being received, the jobs in the holding queue are not executed, unless the user intentionally transfers them to the printing queue. 
   In accordance with the present embodiment, when printing jobs are transferred from a host computer to the image processing apparatus  3 , the apparatus designates the kinds of the queues to receive them. For the job joint of the present embodiment, the jobs are received in the holding queue in advance for a job joint. In  FIG. 10 , jobs A, B, and C in the holding queue are those to be joined. A job joint is instructed using a job description by the JDL (Job Description Language), which will be described later. The JDL is an expansion of the PDL, and the JDL job is handled as a kind of PDL job. To execute a job joint, a JDL job, which includes an instruction of the job joint, is provided by a host computer for the printing queue for its printing. As shown in  FIG. 10 , when a job arrives at the head of the printing queue, it begins to execute processing a job joint as instructed by the job description written in the JDL. Here, the JDL job S, shown in  FIG. 10 , is the one that instructs the addition-joint of the jobs A, B, and C. 
     FIGS. 11A ,  11 B,  11 C,  11 D,  11 E,  11 F,  11 G and  11 H are views which illustrate the example of a JDL job. At first, the first line in  FIG. 11A  reading “##JDL” indicates that the current job is not any one of the general PDL jobs, but a JDL job. The second line in  FIG. 11A  reading “#J:A+B+C” is an instruction that the jobs A, B, and C should be joined in that order. Incidentally, in accordance with the present embodiment, a line having the mark “#” at the head thereof is handled as a comment line for the PDL. Therefore, the current job is not regarded as any of the PDL jobs. 
   Now, the second line in  FIG. 11B  is an instruction that the first page and the second page of the job A, the job C, and the third page of the job A should be joined in that order. Then, the second line in  FIG. 11C  is an instruction that the job B and job C should be joined for composition. The second line in  FIG. 11D  is an instruction that the whole jobs instructed by the third line for a job joint should be printed in the mode of four-in-one printing. Likewise,  FIGS. 11E ,  11 F, and  11 G include the instructions that each of the job joints should be printed in the modes of duplex printing, sort printing, and staple-sort printing, respectively. Lastly, the second line in  FIG. 11H  is an instruction that the job joints should be printed in four copies. Here, each of the modes is described in  FIGS. 11A to 11H  individually, but it may be possible to designate each of the modes in combination by arranging those lines of the mode designations side by side, as required. However, if one mode is not consistent with another, in combination, such as two-in-one and four-in-one, the one designated later becomes effective. 
     FIG. 12  is a flowchart which illustrates the control flow of the image processing apparatus  3  in accordance with the first embodiment. At first, in S 11 , the reception task is executed to receive printing jobs at a request from any one of the host computers on the network. Then, in S 12 , it is determined whether or not such printing jobs are transferred together with any designation to retain them in the holding queue. If affirmative, the jobs are held in the holding queue in S 13 . On the other hand, if the printing queue is designated, no particular designation is provided for any of the queues, the jobs are held in the printing queue in S 14 . 
   Meanwhile, in S 21  in  FIG. 12 , the development and printing tasks are, at first, executed to pick up a job at the head of the printing queue. Then, in S 22 , it is determined whether or not the job thus picked up is a JDL job in accordance with the first line that indicates “##JDL”. If negative, the development is executed, and printing is processed as a usual PDL job in S 23 . Regarding the development and printing processes, the description will be made later in conjunction with  FIG. 13 . On the other hand, if the job thus picked up is the one described by the JDL, each of the modes designated by the lines beginning with “#M:” is defined as JDL modes in S 24 . Then, in S 25 , each page in each job is sorted in S 25  in accordance with the order designated by the line beginning with “#J:, as described in conjunction with  FIG. 11 , for example. At this juncture, each of the jobs is transferred from the holding queue and joined together. When the job sorting is completed, the development and printing processes are executed in S 26  as in S 23 . 
     FIG. 13  is a flowchart which shows the development and printing processes in detail. At first, in S 31 , each of the modes designated for the PDL job is defined for each of the job processing modes thereof. Then, in S 32 , it is determined whether or not the current job is a job joint instructed by the job description written in the JDL. If affirmative, the modes defined in S 31  are substituted in S 33  by the JDL modes defined in the S 24  shown in  FIG. 12 . This is because, in a job joint, each of the modes designated in the JDL job is given priority to any one of the modes designated in each of the job joints when being processed. As a result, if a four-in-one is designated in the JDL job, for example, this designation is given priority, and all the pages are printed in this mode of four-in-one even if a two-in-one is instructed for a job A; a four-in-one, for a job B; and an ordinary printing, for a job C. 
   Then, in S 34 , in accordance with each of the modes designated, a printer  1  is notified of whether the mode is duplex, sort, or staple-sort. Subsequently, in S 35 , it is determined whether or not any four-in-one mode or composition-mode is designated. If neither of them are designated, each of the pages is developed in S 40  on the full-page image memory one after another. The image data thus developed are transferred to the printer  1  for printing. At this juncture, if the task is a job joint, each of the pages of the job joint is transferred one after another in order of those being put together. After all the pages are printed, the development and print processes terminate. In S 35 , however, if the job is in a four-in-one mode, the first page is developed in the first quarter area on the full-page image memory in S 36 , and in S 37 , it is determined whether or not all the four pages are completed, that is, it is determined whether the four areas on the full-page image memory are all filled or there are still any areas yet to be filled. If there are some pages still remaining or all the four areas are not completely filled, the process returns to S 36 , and the next page is developed on the next quarter area on the full-page memory. Then, the process proceeds to S 37  again. On the other hand, if there is no page left to be filled or all the four areas are completely filled, the image data on the full-page image memory are transferred to the printer  1  for printing. On the way, the four-in-one printing is executable as described in conjunction with  FIG. 8B . When the printing is over, it is determined whether or not there are still any other pages to be printed in S 39 . If affirmative, the process returns to S 36 , and the next page is developed on the first quarter area on the full-page image memory. Then, the process proceeds to S 37 . In S 39 , if no page remains at all, the development and printing processes terminate. 
   Meanwhile, if the mode is composition in S 35 , the first page is developed on the full-page image memory in S 41 . Then, in S 42 , it is determined whether or not any pages still remain to be composed with the preceding page. If affirmative, the process returns to S 41 , the next page is developed on the full-page image memory. The process proceeds to S 42  again. For the second development and on in S 41 , the full-page image memory is not erased before such a development process, nor are any white data written on the memory at the time of development. In this way, all the portions of data on plural pages, with the exception of white data, are substituted one after another, thus making it possible to execute a composed printing, as described in conjunction with the composition-job joint illustrated in  FIG. 1 . In S 42 , if there are no other pages to be composed, the image data on the full-page image memory are transferred to the printer  1  for printing. When printing is completed, it is determined whether or not any pages still remain in S 44 . If affirmative, the process returns to S 41  where the full-page image memory is erased, and then, the next page is developed on the full-page image memory. The process proceeds to S 42  again. If there are no other pages remaining in S 44 , the development and printing processes terminate. 
   Second Embodiment 
   Reducing Sheet Consumption 
   In accordance with the first embodiment, a job joint is designated using the JDL job. For a second embodiment, however, a structure is arranged to automatically designate a job joint if jobs satisfy a certain condition. Here, the description of the same portions as those of the first embodiment will be omitted. In conjunction with  FIG. 14 ,  FIG. 15 , and  FIG. 16 , a description will be made of the portions that differ from the first embodiment. 
   The second embodiment thus structured is aimed at reducing the consumption of sheets. Even when there is no immediate need for any printed-out sheets, it may sometimes be desirable to have the sources of print out readily available at hand. Each job of the kind is put together for printing in the mode of four-in-one, or the like, in order to reduce the sheet consumption. 
     FIG. 14  is a view which illustrates queues arranged in the spooler in accordance with the second embodiment. As in the first embodiment, there are a holding queue and a printing queue. In addition, the one called a joint queue is arranged anew. For the image processing apparatus of the present embodiment, it is devices to designate which one of the three queues is the destination for a printing job to be transferred from a host computer. The job that enters the printing queue is automatically printed when it arrives at the head of the queue. On the other hand, the job that enters the holding queue is not printed, unless it is transferred to the printing queue. Meanwhile, the job that enters the joint queue is automatically printed individually, or jointly with some other jobs, when it satisfies a certain condition. In accordance with the present embodiment, jobs to be joined should be retained in the joint queue.  FIG. 14  illustrates a state where the jobs A, C and D, which are retained in the joint queue, are automatically joined to produce a job joint X when a certain condition is satisfied, and then, transferred to the printing queue. Here, for the reasons to be described later, the job D is divided into jobs D 1  and D 2 . While job D 1  is joined with jobs A and C to become job X, job D 2  is returned to the last of the joint queue. The job joint X is automatically printed when it arrives at the head of the printing queue. 
     FIG. 15  is a flowchart which illustrates the control flow of the image processing apparatus  3  in accordance with the second embodiment. With the joint task that is characteristic of the present embodiment, a job at the head of the joint queue is picked up in S 51 . In  FIG. 14 , job A of the user a is picked up. Then, in S 52 , the other jobs of the user, whose job has been picked up in S 51 , are retrieved from among those retained in the joint queue. In  FIG. 14 , job C and job D are retrieved. Subsequently, if each of the jobs is joined, it is determined whether or not the number of pages is more than the one-sheet portion of an output sheet. The number of pages per one output sheet means two if the mode is duplex or four if the mode is four-in-one. In other words, with the pages that are less than those numbers, one output sheet is not fully filled. If the number of pages is more than the portion of one output sheet, each of the jobs is joined in S 55  and transferred to the printing queue for the formation of images. At this juncture, the jobs that are joined and transferred to the printing queue are deleted from the joint queue. Also, the number of pages after the job joint is not a multiple of the number of pages on the portion of one output sheet, the pages in odd number are not joined, and returned to the joint queue as a remaining job. For example, in accordance with the example shown in  FIG. 14 , if job A has two pages, job C has one page, and job D has two pages on the assumption that the job joint is printed in the mode of four-in-one, job A, job C, and the first page of job D are joined to be a job X, while the second page of job D is returned to the last of the joint queue. This is a process not to print on a sheet unless the sheet can be filled with full images if the circumstances admit of it. 
   On the other hand, if the number of pages is not more than the portion of one output sheet in the S 53 , it is determined whether or not the intended job is such as the one among the respective jobs picked up by the user in S 54 , which is still retained after a given time has elapsed since its entrance in the joint queue. If such jobs still remain in the queue, all the jobs are joined in S 55  and transferred to the printing queue for the formation of images. At this juncture, the jobs that are put together and transferred to the printing queue are deleted from the joint queue. This is a process not to allow jobs to reside in the joint queue without being joined for a long time. Also, in S 54 , instead of detecting the elapsed time, it may be possible to determine the length of stay in accordance with the date of entrance by detecting whether or not such a job enters the queue before yesterday&#39;s date, or the like, for example. Also, if the holding capacity of a hard disk becomes less than a given amount, it may be possible to print the jobs still remaining in the queue, beginning with the oldest one, and to delete them one after another. 
   Meanwhile, in S 54 , if there are no jobs that are left intact after a given time has elapsed or in S 55 , the transfer to the printing queue is completed, the next job is picked up in S 56 , and then, the process returns to the S 52 . In  FIG. 14 , the job B of the user b is picked up. 
     FIG. 16  is a view which illustrates the printing format of a job joint in accordance with the present embodiment. Here, since the jobs in the joint queue are automatically joined, there is no need for mode designations using any job descriptions by the JDL, as in the case of the first embodiment. As a result, it is possible to fix the format of a job joint. In accordance with the present embodiment, it is fixed to the single-sided one page four-in-one mode without sorting and stapling, as shown in  FIG. 16 . Even if each kind of mode is designated for each of the jobs that should be joined, such a designation is disregarded when a job joint is performed. As jobs in the joint queue are automatically joined, it is arranged to describe the name of a user and data of print on the header of each sheet in order to define each of the users and jobs that have been printed, respectively. Further, on the upper part of each page placed side by side in the mode of four-in-one, it is arranged to describe the page number of a specific job accordingly. Moreover, in order to make the boundary of each job clear, it is separated by thick lines, respectively. 
   Third Embodiment 
   Instructing a Job Joint from an Operating Unit 
   In accordance with the first embodiment, a job joint is instructed in the image processing apparatus by the application of the job description by the JDL. However, in a third embodiment of the present invention, a structure is arranged so that a job joint is instructed through the operating unit of the image processing apparatus. Also, as one of the jobs to be joined, image data read out by means of the image reader of a color copying machine, which serves as the image formation apparatus  1 , are regarded as a printing job among those printing jobs per se, and the structure is arranged to include such image data in a job joint. The description will be omitted as to the same portions as those in the first embodiment. In conjunction with  FIG. 17 ,  FIG. 18 ,  FIG. 19A ,  FIG. 19B  and  FIG. 20 , a description will be made of those portions that differ from the first embodiment. 
     FIG. 17  is a block diagram which shows the image formation system comprising an image processing apparatus  3  and an image forming apparatus  1  dealing with the color PDL in accordance with a third embodiment of the present invention. 
   The PDL data transferred from a host computer through a network  4  are developed to the raster image data in the image processing apparatus  3 , and transferred to the image forming apparatus  1  as raster image data  12 . The raster image data are formed by a total of twenty-four bits, eight bits each of RGB per pixel. The raster image data  12  thus transferred are held in a spooler hard disk  56  as they are through an external interface circuit  51 . The spooler hard disk  56  has a sufficient capacity of holding raster image data of plural page portions. The raster image data thus retained in the spooler are read out in a certain condition and written on an image memory  58 . The RGB data written on the image memory  58  are read out and converted by an image processor  33  into YMCK image data, thus being transferred to an image formation unit  60  where image formation is executed. 
   As described in conjunction with  FIG. 3 , the image reader  32  is to read documents and to obtain RGB data. When the image forming apparatus  1  functions as a copying machine, the RGB data, which are read out by the image reader  32 , are once held on the spooler hard disk  56 , and then, transferred to the image memory  58  and read out for printing. 
   The controller  52  is to control the entire system of the image forming apparatus  1 . In addition to communicating with the image processing apparatus  3 , it controls the DF (automatic document feeder)  341 , spooler sorter  42  and others described in conjunction with  FIG. 3 . The operating unit  54  is to instruct the set up of various modes of copying operation and the start of copying. Also, as described later, it instructs a job joint. Here, a reference numeral  61  designates a CPU bus to connect these units. 
     FIG. 18  is a view which illustrates the state of job distribution on the spooler disk  56 . In accordance with the present embodiment, two kinds of queues, printing and holding, are provided for the spooler hard disk  56 . These queues function as in the first embodiment, with the exception of the printing jobs existing in the queues, which are prepared to deal with raster images. However, in these queues, there are mixed jobs of a copying machine that prints images read out by the image reader (copying jobs) in addition to the printing jobs, per se, that have been transferred from a host computer through the image processing apparatus. 
   In  FIG. 18 , there is, at first, a job S 1 , which is mixed in the holding queue to deal with the image data read out by a scanner as a printing job by a copying machine in addition to the printing jobs, per se, namely, job A, job B and job D. Further, there is a job DFn that indicates each of the documents stacked on the DF (automatic document feeder)  31 , which virtually resides in the holding queue. The suffix n of the DFn indicates an nth document. This job, DFn, does not retain any image data as an entity on it, but it indicates an image data that should be obtainable if an nth document is read out from among those stacked on the DF. 
   On the other hand, there are also mixed in the printing queue the copying jobs S 2  and S 3 , in addition to job C, which is a printing job, per se. These are transferred to the image memory  58 , beginning with a job at the head of this queue and printed one after another. In accordance with the present embodiment, both printing and copying jobs are performed in the same preferential order, but since a copying job requires instantaneous operation, more so than a printing job, it may be possible to arrange a structure so that the priority is given to a copying job. 
   In accordance with the present embodiment, jobs to be joined are arranged in the holding queue. The jobs in the holding queue are selected for a job joint. The jobs thus joined are transferred to the printing queue for printing when arrived at the head thereof. In  FIG. 18 , jobs A, B, S 1 , DF 1 , and DF 2  are joined, and the job joint X is transferred to the printing queue. In other words, the job A transferred from a computer, the job S 1  read out by the scanner as a copying job, the job DF 1  that indicates the first document on the DF, the job DF 2  that indicates the second document on the DF, and the job B transferred from a computer, are joined, in that order, and transferred to the printing queue for printing. In this way, the printing jobs, per se, and copying jobs are executed as a job joint. Therefore, as described in conjunction with the first embodiment, these jobs can be printed continuously or both of them can be mixed, to execute a four-in-one printing, a duplex printing, and others. 
   In accordance with the present embodiment, the job joint is performed by the operator by issuing instructions, accordingly, through the operation unit  54  of the image forming apparatus.  FIGS. 19A and 19B  are views which illustrate the messages appearing on the screen of the liquid crystal display panel (not shown) of the operation unit  54 . On the liquid crystal display panel, touch keys are arranged. When a job joint key (not shown) on the operation unit is depressed, a screen represented in  FIG. 19A  appears on the liquid crystal display panel. On the upper part of the screen shown in  FIG. 19A , operational messages appear, and on the lower part thereof, a list appears to indicate jobs retained in the holding queue. The number of jobs to be joined is inputted by use of ten keys, and then, the OK key on the panel is depressed. On the middle part of the screen shown in  FIG. 19A , the job numbers for which the job joint is requested are indicated in order of those being joined. With the completion of all the instructions required, the exit key is depressed. 
   On the other hand, in order to set each of the modes applicable to a job joint, the mode setup key appearing on the screen represented in  FIG. 19A  is depressed. Then, the screen changes to the one shown in  FIG. 19B . The setting mode is selected by moving the cursor by use of the up/down key (not shown), and then, the desired numbers are entered by use of the ten keys as to the upper two modes, and each of the one and off modes is switched over by use of the left/right key (not shown) for the lower four modes. In this respect, the up/down key, although not shown, may be an arrow-shaped key that serves as a zooming key or a density adjustment key, provided for the operation panel of a copying machine, or the like. Six modes can be set in  FIG. 19B . It is possible to indicate the number of printing sheets for the current job joint; the numeral of N for the mode of N-in-one; the requirements of a duplex printing, of a sort printing, of a spool printing, and of a composition printing from the top, respectively. Here, if 1 is inputted as the N for the N-in-one mode, the set up is made for an ordinary printing in which one page is printed on one sheet. 
     FIG. 20  is a flowchart, which illustrates the control flow of the image forming apparatus  1  in accordance with the third embodiment. At first, in S 61 , the reception task begins receiving communication form the image processing apparatus  3  if there are printing jobs in it. Then, in S 62 , it is determined whether or not the holding queue is designated for such printing jobs. If affirmative, the jobs are held in the holding queue in S 63 . If negative, the jobs are held in the printing queue in S 64 . 
   Then, in S 81 , the printing task picks up a job at the head of the printing queue. In S 82 , each of the pages retained in the job is transferred to the image memory  58  one after other printing. After that, the process returns to S 81 . 
   Now, a description will be made of the job joint process execution task, which is actuated when the job joint key (not shown) of the operation unit is depressed. For the job joint process execution task, the screens of the liquid crystal panel of the operation unit are displayed in S 71 , at first, as shown in  FIGS. 19A and 19B , in order to receiving job joint instructions from the operation unit. Then, when the exit key is depressed, it is determined whether or not any DF jobs, that is, job DFn, are included in the job joint S 72 . If affirmative, the DF is controlled in S 73  to read documents on the DF one after another, and then, substances of image data thus read out are being held in the holding queue. Thereafter, the DF jobs are handled in the same way as handling the copying jobs. 
   Then, in S 74 , it is determined whether or not the job joint should be printed in the mode of N-in-one. If affirmative, the raster image data that form each of the pages are contracted to 1/N in S 75 . For example, if the mode is four-in-one, an image is contracted to a ½ high, and a ½ wide, thus, to a ¼ square measure. 
   Subsequently, in S 76 , it is determined whether or not any composition-joint is executed for the jobs. If affirmative, the jobs are being printed together with the composition processing in S 77 . More specifically, in S 77 , each of the pages that should be composed is substituted on the image memory  58  one after another for composition. When images on the second pages are substituted on the image memory, no white data are written on the memory. As a result, on the image memory  58 , images are composed by the images on each of the pages included in the job joint, which are overlaid one after another, with the exception of white data. When the substitutions of all the jobs are completed for the composition joint, the image data on the image memory  58  are transferred to the image formation unit to form the images. 
   On the other hand, if no composition joint is executed, each of the pages in the jobs that have been joined in S 78  are printed one after another. More specifically, image data corresponding to each of the pages are written on the image memory  58 , and then, read out and transferred to the image formation unit to form images. In case of the N-in-one printing mode, images on each of the corresponding N pages are written on the N numbers of areas of the image memory  58 , and then, printed accordingly. Also, preceding the printing, the duplex mode, sort mode, staple mode, and number of sheets set up on the screen, shown in  FIG. 19B , are notified to the image formation unit  60 . In accordance with the notified modes, the respective job joint is printed accordingly. 
   Fourth Embodiment 
   Job Joint Instruction Through the Operation Unit of an Image Processing Apparatus Between a Host Computer and a Printer 
   In accordance with the first and second embodiments, a job joint is executed when developing the PDL jobs into raster images for its transfer to a printer, and in accordance with the third embodiment, a job joint is executed after the development into raster images. However, in accordance with a fourth embodiment of the present invention, a structure is arranged so that a job joint is executed at the PDL level. Also, while a job joint is instructed using the JDL job for the first embodiment, jobs are automatically joined for the second embodiment, and a job joint is instructed through the operation unit of an image forming apparatus for the third embodiment, a structure is arranged for the fourth embodiment to instruct a job joint through the operation unit of an image processing apparatus. The description of the same portions as those of the first embodiment will be omitted. Here, in conjunction with  FIG. 21  and  FIGS. 22A and 22B , a description will be made of the portions that differ from the first embodiment. 
     FIG. 21  is a view which illustrates queues arranged for the spooler with the fourth embodiment. As in the first embodiment, a holding queue and a printing queue are arranged. The objects of its provisions are the same as those of the first embodiment. For the fourth embodiment, the jobs to be joined are held in the holding queue, and a job joint is executed by instructions issued through the operation unit in the image processing apparatus  3 .  FIG. 21  is a view which illustrates a state where jobs A, C, and D are joined, and then, a job joint X is being transferred to the printing queue. For the first embodiment, the job joint is executed along each of the pages being developed for printing when a JDL job arrives at the head of the printing queue. For the present embodiment, however, a job joint is executed immediately when an instruction is issued through the operation unit therefor, and a job joint is transferred to the last of the printing queue. This job joint processing is performed by generating one PDL data by joining the PDL data for plural jobs to be joined one after another. The PDL data thus generated is handled as a job joint. 
     FIG. 22A  is a view which shows a screen used for instructing a job joint, which is displayed on the operation unit in the image processing apparatus  3 . The operator inputs the number of jobs to be joined through the ten keys, and then, depresses the OK key. If certain jobs are selected for a job joint and an ID number has been set for such jobs, the screen changes to the one represented in  FIG. 22B , where the user is requested to input such an ID. This is devised so that no other users can freely put jobs together. Here, in accordance with the present embodiment, an ID is set for each of the jobs. It is devices that the IDs are transferred from a host computer together with a printing job if any protection is needed by the use of IDs. However, it may be possible to set IDs per user or to adopt a method whereby to register IDs per user in the image processing apparatus  3 . 
   Fifth Embodiment 
   Performing a Continuous Printing by Means of a Virtual Job Joint 
   In accordance with the first embodiment, jobs are joined explicitly, and then, a continuous printing, a duplex printing, a four-in-one printing, a sort printing, and others, are executed as the case may be. For a fifth embodiment, however, a structure is arranged to automatically or virtually provide a job joint for a continuous printing. The description of the same portions as those of the first embodiment will be omitted. Here, in conjunction with  FIG. 23  and  FIG. 24 , a description will be made of the portions that differ from the first embodiment. 
   The fifth embodiment is structured to aim to provide a virtual job joint for a continuous printing, so as to make the processing time shorter for plural jobs, as a whole, as described in conjunction with  FIGS. 6A and 6B . At the same time, it is aimed to avoid any influences given to the result of each job processing, because of the explicit job joint. In other words, it is devised so that there is no difference in the result of printing whether each of the jobs are joined or not. 
     FIG. 23  is a view which illustrates a printing queue arranged for a spooler in accordance with the fifth embodiment. This queue may be a holding one, as in the first embodiment, but the virtual job joint for the present embodiment is assumed to be executed for the jobs retained in the printing queue as its object. In  FIG. 23 , five printing jobs are retained in the printing queue. Each of the jobs is different in the modes as to the size of sheet, single or duplex, sort or non-sort, among some others. In accordance with the first, third, and fourth embodiments, the job joint is executed by the instruction issued by the user. Therefore, whether or not any jobs having different printing modes are put together depends on the user who issues instructions for such a job joint. Usually, the printing jobs having the same printing mode are put together. Also, even when printing jobs are joined with different printing modes, it is possible to designate a printing mode applicable to a job joint. For example, in the case of the JDL, a JDL mode, which is applicable to the entire job, is applied in order to make the printing modes agreeable with each of the jobs involved. Meanwhile, in accordance with the second embodiment, jobs are automatically joined. Therefore, the printing modes of a job joint are fixed for a certain specific mode, unconditionally. As has been described, if printing modes change, the result of a processed printing job is caused to differ from the original one inevitably. Therefore, for the present embodiment, in order to remove such a cause, it is arranged to automatically pick up only the jobs that can be printed continuously, without changing printing modes for the intended continuous printing. The combination of jobs that admits of a continuous printing, without changing printing modes, is dependent on the structure of a printer to be used. However, in accordance with the present embodiment, a continuous printing is made possible only when each of the modes of sheet size and single or duplex is the same for non-sorting. This arrangement is necessary, because if the sizes of sheets are different, there is a need for changing sheet feeder cassettes during a continuous printing. Also, for a duplex printing and a single printing, the destinations of delivery trays are different, thus making its control more complicated. Also, if sorting jobs themselves are joined automatically, the sorted jobs are mixed on the delivery tray, as shown in  FIGS. 9A and 9B , thus, the user is required to separate them manually after all. Here, in accordance with the example shown in  FIG. 23 , the job A and job E are a job combination that enables a continuous printing without changing printing modes. 
     FIG. 24  is a flowchart which illustrates the control flow of the image processing apparatus  3  in accordance with the fifth embodiment. This flowchart corresponds to the one used for the development and printing task for the first embodiment described in conjunction with  FIG. 12 . For the fifth embodiment, the development and printing tasks are, at first, to pick up a job at the head of the printing queue in S 91 . Here, in accordance with the example shown in  FIG. 23 , job A is picked up. Then, in S 92 , such a job and the jobs that enable a virtual job joint are retrieved from among those retained in the printing queue. The jobs that enable a virtual job joint are jobs that make it possible to execute a continuous printing without changing modes as described above. In accordance with the example shown in  FIG. 23 , job E is retrieved. Then, in S 93 , the printer is notified of the printing modes of the entire jobs that have been virtually joined. In accordance with the example in  FIG. 23 , the modes thus notified are A4, single, and non-sort. 
   Then, in S 94 , job A and job E, which are virtually joined, are printed in succession, as described in conjunction with  FIGS. 6A and 6B . 
   In the case of a printer used for the present embodiment, it is possible to execute a virtual job joint on condition that the sizes of sheets used for printing are the same, and the modes of single or duplex are the same for non-sorting, but if a printer can change sheet feeder cassettes during a continuous printing, it is possible to execute a virtual job joint on a condition that the single or duplex modes are the same for non-sorting. This is also an embodiment. In such a case, jobs A, B, and E can be virtually joined for a continuous printing, in accordance with the example shown in  FIG. 23 . The same is applicable to the single or duplex mode. If a printer to be used is capable of switching the delivery trays at each destination of deliveries during a continuous printing, it is possible to execute a virtual job joint, even if the modes of single or duplex are different. This is also one of the embodiments. Further, regarding the sorting mode, if delivery trays at the destination of non-sorting and that of sorting are different, it is possible to execute a virtual job joint for a plurality of non-sorting jobs and one sorting job. This is also one of the embodiments. Also, if a sufficient number of trays are available at the destinations when sorting is executed, a plurality of sorting jobs can be virtually joined by arranging a structure so that a control is made to group the trays at destinations per job and to avoid any mixture of sorted sheets between jobs. This is also another one of the embodiments. 
   Other Embodiments 
   In accordance with the embodiments described above, the image data transferred from a host computer are received in the PDL data format. The features of this format are such that character data, graphic data, and raster image data can be handled uniformly, but it also constitutes one of the embodiments that, instead of the PDL data, only raster image data are received and written on the image memory. In this case, no complicated development is needed for execution. As a result, there is no need for the provisions of a high speed CPU, ROM, RAM, and others, thus making it possible to keep costs lower. 
   Also, for the embodiments described above, the raster image data are developed on the image memory or held on the spooler hard disk as they are. This contributes to making the hardware structure simpler. However, instead of developing them as they are, it may be possible to hold them on the image memory or the spooler hard disk after giving them some compression process. This is also one of the embodiments. In this case, the hardware structure becomes more complicated, but it is possible to reduce the size of the memory efficiently. 
   In accordance with each of the embodiments described above, image data, such as PDL data, are received by communication with an external host computer, or the like. It also constitutes another one of the embodiments if an arrangement is made so as to receive image data from an inner floppy disk. Here, instead of a floppy disk, a hard disk, or the like, is adoptable for the same purpose. Also, it may be possible to receive PDL data produced by use of an application program (not shown) on the main memory or to transfer it therefrom. 
   Also, in accordance with each of the embodiments described above, the image forming apparatus  1  is provided separately from the image processing apparatus  3 , but it may be possible to provide them together. 
     FIG. 25  is a view which shows a state where a program with respect to the present embodiment is loaded on a server installed on a network through a storage medium, and at least, an index, a reception task, a development printing task, and a joint task, described earlier, are stored on the storage medium. 
   When the functions of the image processing apparatus of the present embodiment are executed by means of a host computer, such as a server installed on the network, it is also possible to apply the present invention, even if such functions are supplied to the host computer, an image forming apparatus, or an image processing apparatus by loading a group of information, including the program through an FD, a CD-ROM, a flash memory or other memory means, or through a network. 
   In this way, a job joint is possible. In the meantime, if any conflicts take place among the jobs, the one designated last is validated. 
   As described above, when a job joint is performed, it is determined whether or not the numbers of pages are more than a portion of one output sheet. If affirmative, the job joint is possible. 
   As described above, it is possible to instruct a job joint through an operational panel on the printer side. 
   As described above, it is possible to provide a storage medium for storing tasks that perform a job joint. 
   Also, the present invention is applicable to a system comprising a plurality of equipment or to an apparatus having one device. It is, of course, possible to apply the present invention even when a program is supplied to a system or an apparatus for its implementation. In this case, a storage medium that stores a program embodying the present invention is regarded as a constituent of the present invention. Then, by reading out such a program from the storage medium to a system or an apparatus, it is made possible for the system or the apparatus to operate in such a manner as predetermined by the program. 
   As has been described above, in accordance with the present invention, there is an effect to provide an apparatus for controlling image processing, which is capable of applying the various processes, which have been applied per job, to a plurality of printing jobs, as a whole, by joining and regarding them as one job, and to provide a method for controlling image processing as well.