Patent Abstract:
Conventionally, when counterfeit judgment processing by using electronic watermark is performed in a printer driver, a printing speed is lowered due to heavy load. To solve the problem, in the printer driver, first, it is judged whether or not image data indicated by input print information is in high quality. If the image data is in high quality, it is judged whether or not the image data represents a particular image. If the image data represents the particular image, predetermined processing is performed on the image data. This minimizes the execution of counterfeit judgment processing and reduces the load.

Full Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an image forming system and its control method, and more particularly, to an image forming system and its control method for forming an image based on image data with fidelity on a print medium.  
         BACKGROUND OF THE INVENTION  
         [0002]    In recent years, in accordance with improvement in performance of color image reading devices (scanners) and color printers, there is an increasing risk of counterfeiting a particular original such as a bank note or a negotiable instrument by reading the original from a color scanner and outputting the read image data to a color printer.  
           [0003]    To prevent the counterfeiting, color copying machines, having a construction as a combination of color scanner and color printer, often incorporate a counterfeit prevention device which discriminates whether or not an original to be processed is such particular original and performs duplication prohibition processing.  
           [0004]    However, the counterfeit prevention device used in the above color copying machines operate only in duplication processing. Accordingly, in a system where a scanner is connected to a printer via a host computer, there is a possibility that a counterfeit can be obtained by once reading a duplication-prohibited original by the scanner or the like then storing the read image data, and outputting the stored image data by the color printer. Further, generally, the above conventional counterfeit prevention device is expensive, therefore it is difficult to incorporate the device into small and low-price color copying machines and printers.  
           [0005]    On the other hand, a so-called electronic watermark technique of embedding copyright information or the like in digital contents of image or music, is being practically used, and the application of electronic watermark technique to the above-described counterfeit preventing device is proposed. For example, counterfeiting can be prevented by embedding information processed by the electronic watermark technique in a duplication-prohibited printed matter (particular original), and detecting the electronic watermark information upon duplication or printing of the printed matter.  
           [0006]    However, in a case where counterfeit judgment processing based on the above-described electronic watermark is executed in a printer driver in a host computer, heavy load is posed on the CPU. Accordingly, the printing speed in the system or apparatus is seriously reduced by execution of the counterfeit judgment processing.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention has been proposed to solve the conventional problems, and has its object to provide an image forming apparatus and its control method which realize high speed printing by reducing load of counterfeit judgment processing in a printer driver.  
           [0008]    According to the present invention, the foregoing object is attained by providing a control method for an image forming system where an image processing apparatus for generating image data is connected to an image forming apparatus for forming a visible image based on the image data on a print medium, in the image processing apparatus, the method comprising: an input step of inputting print information; an object image judgment step of judging whether or not image data indicated by the print information inputted at the input step is in high quality; a particular image judgment step of, if it is judged at the object image judgment step that the image data is in high quality, judging whether or not the image data represents a particular image; and a particular image processing step of, if it is judged at the particular image judgment step that the image represents the particular image, performing predetermined processing.  
           [0009]    In accordance with the present invention as described above, by performing particular image judgment processing, i.e., counterfeit judgment processing, only on a high-quality image, the load is reduced and high-speed printing can be performed.  
           [0010]    Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
         [0012]    [0012]FIG. 1 a block diagram showing the configuration of printing system according to a first embodiment of the present invention;  
         [0013]    [0013]FIG. 2 is a block diagram showing the construction of graphic subsystem;  
         [0014]    [0014]FIGS. 3 and 4 are flowchart showing counterfeit judgment processing;  
         [0015]    [0015]FIG. 5 is an example of warning dialog to a user;  
         [0016]    [0016]FIG. 6 is a block diagram showing the construction of formatter controller;  
         [0017]    [0017]FIG. 7 is a cross-sectional view of printer engine;  
         [0018]    [0018]FIG. 8 is a flowchart showing the counterfeit judgment processing according to a second embodiment of the present invention; and  
         [0019]    [0019]FIG. 9 is a flowchart showing a modification to the second embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.  
         [0021]    &lt;First Embodiment&gt; 
         [0022]    [0022]FIG. 1 is a block diagram showing the configuration of printing system using a color laserbeam printer to which a first embodiment of the present invention is applied.  
         [0023]    In FIG. 1, reference numeral  200  denotes a host computer which outputs print information including print data and control code via an interface (I/F)  203  to a printer  100 . The host computer  200  is a computer system having a keyboard  210  as an input device, a mouse  211  as a pointing device and a display monitor  220  as a display device. Further, when a scanner  300  is connected to the host computer, image data obtained by optically reading an original image from the scanner  300  can be inputted into the host computer. The host computer  200  operates by a basic OS such as Windows NT and Windows  95 ( 98 ) (trademarks by Microsoft Corporation).  
         [0024]    On the host computer  200  side, the functions on the basic OS regarding the present embodiment are briefly classified into application software  201  and a graphic subsystem  202 .  
         [0025]    The application software  201  is, e.g., application software which operates on basic software such as a word processing program or a spreadsheet program.  
         [0026]    As shown in FIG. 2, the graphic subsystem  202  has a graphic device interface (hereinafter GDI)  2021  as a part of the functions of the basic OS and a printer driver  2020  as a device driver dynamically linked from the GDI  2021 .  
         [0027]    The printer driver  2020  is called from the GDI  2021  via a Device Driver Interface (DDI), and performs processing in accordance with a device upon each drawing object. The processing system of the printer driver  2020  divides into a PDL mode type  2023  and a image mode type  2024 , and one of them is selected in correspondence with input data.  
         [0028]    The PDL mode type is provided for a printer having a controller capable of processing a control command called PDL (Page Description Language). As soon as the printer driver  2020  converts the print information forwarded via the DDI into a PDL command, it transmits the command via the GDI  2028  to the printer  100 .  
         [0029]    As the processing by the printer driver  2020  in the PDL mode type is merely generating a command from the data from the DDI, it can be considered that this processing is light-loaded processing for the driver.  
         [0030]    The feature of the PDL mode type is that if the printer  100  has high performance to interpret the PDL command, the printer driver  202  can receive data with high degree of extraction from the GDI  2021  and send the data to the printer  100 , therefore, in normal page printing, the data size to be transferred can be small regardless of resolution and output tonality.  
         [0031]    However, in the PDL mode type, in drawing gradation-processed figure or the like by graphic application software or outputting high-resolution/high tonality image, a large print command is generated, therefore, the processing speed is often extremely lowered.  
         [0032]    On the other hand, in the image mode type, a print image is mapped on memory space ensured on the printer driver  2020  side, to avoid high-level drawing processing on the printer  100  side, and the print image is converted into data which can be directly printed by the printer  100 , then sent to the printer  100 .  
         [0033]    As the processing by the printer driver  2020  in the image mode type, the image mode printer driver  2024  performs drawing processing, using print information inputted via the DDI from the GDI  2021  as in the case of the PDL mode type, on a band memory  2027 , and transmits bitmap data generated on the band memory  2027  via the GDI  2028  to the printer  100 .  
         [0034]    The feature of the image mode type is that drawing processing can be performed on high-resolution color image data and complicated graphic data at a high speed. On the other hand, even in case of drawing characters and/or simple figures, the image data in the entire drawing area is generated in the output resolution and output tonality and transmitted as a print command, therefore, when high-resolution/high tonality characters/graphics are printed at a high speed, the processing time is increased.  
         [0035]    Hereinbelow, counterfeit judgment processing will be described about the PDL mode type processing system and the image mode type processing system in the printer driver  2020  as PDL driver  2023  and image driver  2024 .  
         [0036]    The PDL driver  2023  and the image driver  2024  have counterfeit judgment units  2025  and  2026  respectively, and perform the counterfeit judgment processing by detecting pre-embedded electronic watermark information from image data which satisfies a predetermined resolution condition among print information received from the DDI.  
         [0037]    The print information includes three attributes, “text” indicative of font data, “graphics” indicative of figure vectors, gradation information or the like, and “image” indicative of read photographic image or the like, and different functions are called for the respective attributes. Further, as “image” attribute data includes information on the numbers of pixels in vertical and horizontal directions, the output image size and the like, it is easy to extract only data having the “image” attribute (hereinafter, simply referred to as “image data”) satisfying the above resolution condition when print information has been received from the DDI and process the data.  
         [0038]    Hereinbelow, the counterfeit judgment processing by the counterfeit judgment unit  2025  in the PDL driver  2023  will be described with reference to the flowchart of FIG. 3. Note that as the counterfeit judgment processing by the counterfeit judgment unit  2026  in the image driver  2024  is the same as that in the PDL driver  2023  except that bitmap data is generated on the printer driver  2020  side, the explanation of the processing by the counterfeit judgment unit  2026  will be omitted.  
         [0039]    In FIG. 3, first, at step S 301 , print information is inputted from the DDI. As the print information, image data obtained by reading an original by the scanner  300 , image data pre-stored in a storage medium such as a hard disk (not shown) or the like, as well as image data generated by the application  201 , may be inputted. Next, at step S 302 , it is determined whether or not the input print information represents image (image attribute image) and satisfies a predetermined resolution condition.  
         [0040]    Generally, when a bank note or negotiable instrument is to be duplicated, an original image read by the scanner  300  or the like is to be reproduced with fidelity, image data to be processed has a resolution equal to or higher than a predetermined level. Accordingly, the resolution condition is set to a certain level at which sufficient precision cannot be obtained in a printed output as a counterfeit bank note or negotiable instrument. More specifically, if data resolution upon output is equal to or less than 100 dpi (dot/inch), it can be considered from the output image quality that the obtained output is insufficient as a counterfeit. Accordingly, there is a low probability that image data having resolution equal to or less than 100 dpi is counterfeit data. in the present embodiment, 100 dpi is set as the resolution condition.  
         [0041]    At step S 302 , if it is determined that the input print information is image data having a resolution equal to or less than 100 dpi, the process proceeds to step S 306 , at which the PDL driver  2023  converts the print information into a PDL command as in normal processing, and the process ends.  
         [0042]    On the other hand, if the input print information is image data having a resolution over 100 dpi, the process proceeds to step S 303 , at which electronic watermark detection processing is performed.  
         [0043]    Hereinbelow, the electronic watermark detection processing at step S 303  will be described. In the present embodiment, if particular electronic watermark information indicating duplication prohibition is detected from input image data having resolution over 100 dpi, it is determined that the image data is based on a particular original and there is a high probability that the print processing is made for the purpose of counterfeiting. Next, a method for extracting the electronic watermark information in the present embodiment will be described. Note that the present invention is not limited to this method but any other well-known extraction method can be employed.  
         [0044]    First, the input image data is divided into blocks, and Fourier transform is performed on each block to extract a frequency component. The image data in obtained frequency area is separated into amplitude spectrum and phase spectrum, and a registration signal included in the amplitude spectrum is detected.  
         [0045]    Generally, according to human visual perception characteristics, a signal embedded in a low frequency component is usually recognized as noise in comparison with a signal embedded in a high frequency component. Further, since irreversible compression such as JPEG processing has an effect similar to that of low-pass filter, the high frequency component is eliminated by JPEG compression/expansion processing.  
         [0046]    The registration signal is embedded as an impulse signal to an intermediate frequency area with a level equal to or less than a first frequency level at which the signal is hardly recognized by human eye and equal to or higher than a second frequency level at which the signal is not eliminated by irreversible compression/expansion. Accordingly, the registration signal is detected by extracting an impulse signal included in the amplitude spectrum in a frequency area at the intermediate level.  
         [0047]    Then the scaling factor of the digital image data is calculated based on coordinates of the extracted registration signal (impulse signal).  
         [0048]    In the counterfeit judgment unit  2025 , in the object image which has not been scaling-processed, a frequency component where the impulse signal is embedded is previously determined. Accordingly, the scaling factor is calculated by the ratio between this frequency and a frequency where the impulse signal has been detected.  
         [0049]    For example, assuming that the previously-determined frequency is a, and the frequency where the impulse signal has been detected is b, it is determined that a/b scaling has been performed, which is characteristic of the Well-known Fourier transform.  
         [0050]    Then, a pattern size to detect the electronic watermark information included in the image data is determined, and convolution using the pattern is performed, thereby the electronic watermark information can be detected.  
         [0051]    As a result of the electronic watermark detection processing (S 303 ) as described above, if electronic watermark information indicating duplication prohibition has not been detected (S 304 ), the PDL driver  2023  performs normal PDL command conversion processing at step S 306 . Note that in this case, as the print information is image data, predetermined header information is added to the image data, and the data is converted into the print command.  
         [0052]    On the other hand, if electronic watermark information indicative of duplication prohibition has been detected at step S 304 , the PDL driver  2023  performs counterfeit prevention processing at step S 305 .  
         [0053]    Hereinbelow, the counterfeit prevention processing in the present embodiment will be described with reference to the flowchart of FIG. 4.  
         [0054]    First, at step S 401 , the PDL driver  2023  notifies the OS that the duplication prohibition data is included in the input data. In response to the notification, the OS side displays a warning dialog as shown in FIG. 5 for a user to notify that there is a possibility that the current print processing is made as counterfeiting, i.e., a crime.  
         [0055]    Next, at step S 402 , if the user has selected “NO” (=stop printing) in response to the warning dialog, the PDL driver  2023  stops the printing operation based on the data, and the process ends.  
         [0056]    On the other hand, if the user has selected “Yes” (=continue printing) in response to the warning dialog, the operation history is stored in a hard disk device (not shown) or the like in the host computer  200 , and processing to fill the image with black color or the like is performed as counterfeit prevention (S 403 ), and the routine of the counterfeit prevention processing (S 305 ) ends. Note that the above image filling is merely an example of the counterfeit prevention processing. Any other processing may be used as long as it degrades image quality of image data, i.e., it disturbs reproduction of input image with fidelity.  
         [0057]    If the print operation has not been stopped, the print information outputted from the PDL driver  2023  is inputted into the printer  100  in FIG. 1 via a host I/F  111 .  
         [0058]    The printer  100  is divided into a formatter controller  110  which interprets the print information inputted from the host computer  200  and generates a print image (bitmap image data), and at the same time, controls the overall printer  100 , and a printer engine  140  which receives the print image and forms a visible image on a print sheet.  
         [0059]    The formatter controller  110  is connected to an operation panel  120  having switches and LED display device and the like for the user&#39;s operation and for notifying the user of printer statuses. The operation panel  120  is provided as a part of exterior components of the printer  100 .  
         [0060]    Hereinbelow, the formatter controller  110  in the printer  100  will be described with reference to FIG. 6.  
         [0061]    The formatter controller  110  is a part generally referred to as a PDL controller or the like. The formatter controller  110  has the host interface (I/F)  111  as connection means for connection with the host computer  200 , a reception buffer  1121  as storage means for temporarily storing and managing reception data and the like from the host computer  200 , a transmission buffer  1122  as storage means for temporarily storing and managing transmission data and the like to the host computer  200 , a command interpreter  113  which interprets print data, a print controller  114 , a drawing processor  115 , a page memory  116 , an output controller  130  and the like.  
         [0062]    The host interface  111  which is communication means for transmission/reception of print data with the host computer  200  enables communication in conformance with the IEEE-1284 protocol. Note that the present invention is not limited to this communication protocol, but connection by various protocols may be performed via the network. Further, the interface  111  may be communication means in conformance with IEEE-1394 protocol, USB communication protocol or the like.  
         [0063]    The print data received via the host interface  111  is sequentially stored in the reception buffer  112 , and read and processed by the command interpreter  113  or the drawing processor  115  in accordance with necessity.  
         [0064]    The command interpreter  113  comprises a control program in conformance with the PDL command system and print job control languages. The command interpreter  113  provides instructions to the drawing processor  115  based on the result of interpretation of the print data regarding character printing, figure and image drawing, and provides instructions to the print controller  114  regarding commands for paper selection, reset and the like other than drawing commands.  
         [0065]    The drawing processor  115  has a function as a renderer of sequentially mapping the respective drawing objects of characters and images on the page memory  116 . The output controller  130  converts the content in the page memory  116  into a video signal VDO, and transfers the video signal VDO via a video I/F  150  to the printer engine  140 .  
         [0066]    The printer engine  140  is a printing mechanism to form a permanent visible image on a print sheet based on the received video signal. Hereinbelow, the operation of the printer engine  140  will be described with reference to FIG. 7 showing the construction of the printer engine  140 .  
         [0067]    In FIG. 7, one end of print sheet P supplied from a paper cassette  161  is held by a gripper  154   f , and held on the outer periphery of transfer drum  154 . Respective color latent images formed by an optical unit  170  on an electrostatic drum  151  are developed by respective developers Dy, Dm, Dc and Db for yellow (Y), magenta (M), cyan (C) and black (B) colors, then transferred plural times onto the print sheet on the periphery of the transfer drum, thus a multi-color image is formed. Thereafter, the print sheet P is separated from the transfer drum  154 , then the image is fixed onto the print sheet by a fixing unit  155 , and the print sheet P is discharged from a paper discharging unit  159  onto a paper discharge tray  160 .  
         [0068]    The developers for colors, Dy, Dm, Dc and Db respectively have a rotation shaft on both ends. The developers are held by a developer selection mechanism  152  such that they are rotatable on the shafts. In this arrangement, as shown in FIG. 7, the positions of the respective developers Dy, Dm, Dc and Db can be maintained constant even when the developer selection mechanism  152  rotates on its rotation shaft  152   a.    
         [0069]    In the developer selection mechanism  152  integrated with the developers, when a selected developer has been moved to a developing position, a selection mechanism holding frame  153  is drawn toward the electrostatic drum  151  by a solenoid  153   a , with a support  153   b  as the center, thus the developer selection mechanism  152  is moved toward the electrostatic drum  151 , and developing processing is performed.  
         [0070]    Next, the electrostatic drum  151  is uniformly charged to a predetermined polarity by a charger  156 . The image data VDO mapped as a print image by the formatter controller  110  is converted into a video signal of corresponding pattern, and outputted to a laser driver to drive a semiconductor laser  141 .  
         [0071]    A laser beam emitted from the semiconductor laser  141  is on/off controlled in accordance with the input image data (video signal) VDO, further, the laser beam is swayed in left and right directions by a polygon mirror rotated at a high speed by a scanner motor  143 , to scan-expose the electrostatic drum  151  via a polygon lens  134  and a reflection mirror  144 . Thus a latent image of the image pattern is formed on the electrostatic drum  151 .  
         [0072]    Next, for example, an M (magenta) color electrostatic latent image is developed by the M (magenta) developer Dm, then a first toner image in M (magenta) color is formed on the electrostatic drum  151 .  
         [0073]    On the other hand, the print sheet P is fed at predetermined timing, and a transfer bias voltage of an opposite polarity to that of the toner (e.g., plus polarity) is applied to the transfer drum  154 . Then the first toner image on the electrostatic drum  151  is transferred onto the print sheet P, and at the same time, the print sheet P is electrostatically attracted to the surface of the transfer drum  154 . Thereafter, the residual M (magenta) color toner is removed by a cleaner  157  from the electrostatic drum  151 , in preparation for the latent image formation and development for the next color.  
         [0074]    Then, the second toner image of C (cyan) color, then the third toner image of Y (yellow) color, and the fourth toner image of Bk (black) color are transferred in similar procedures. Note that upon transfer of each color image, a bias voltage higher than the previous transfer is applied to the transfer drum  154 .  
         [0075]    When the front end of the print sheet P where the four color toner images are overlap-transferred approaches a separation position, a separation claw  158  comes into contact with the surface of the transfer drum  154 , to separate the print sheet P from the transfer drum  154 . The print sheet P is conveyed to the fixing unit  155 , then the toner images on the print sheet are fixed to the print sheet, and the print sheet is discharged on the paper discharge tray  160 . The printer engine  140  of the present embodiment enables image output up to 600 dot/inch (dpi) resolution through the above image formation process.  
         [0076]    As described above, according to the present embodiment, in the printer driver  2020 , the electronic watermark detection processing is performed only on image data having a resolution over a predetermined resolution. Since the execution of electronic watermark detection processing can be minimized, the counterfeit prevention function against counterfeiting bank notes, negotiable instruments and the like can be realized while suppressing reduction of total throughput.  
         [0077]    Further, in the present embodiment, the resolution as a criterion as to whether or not the electronic watermark detection processing is performed, i.e., whether or not the counterfeit judgment processing is performed, is 100 dpi. Generally, the resolution of data frequently transferred on the Internet or the like for image print-output is equal to or less than 100 dpi. Accordingly, to skip the counterfeit judgment processing for image data having a resolution equal to or less than 100 dpi is effective in reduction of processing time. Note that in use of another resolution as the criterion of counterfeit judgment processing, there is no change in subject matter of the present invention.  
         [0078]    &lt;Modification to First Embodiment&gt; 
         [0079]    In the above-described embodiment, the counterfeit judgment processing is performed in accordance with whether an output resolution is over a predetermined value, however, in addition to the output resolution, an output image size may be added to the criterion.  
         [0080]    For example, if the size of output image is small even though the output resolution is high, the printed output based on the image data is not used as a counterfeit. Accordingly, the counterfeit judgment processing can be skipped if the output image size is less than a predetermined value (e.g., within 5 cm×5 cm).  
         [0081]    In this manner, the counterfeit judgment processing is performed only if image data has a size equal to or greater than a predetermined size, in addition to a resolution equal to or higher than a predetermined resolution, thereby processing time can be further reduced.  
         [0082]    &lt;Second Embodiment&gt; 
         [0083]    Hereinbelow, a second embodiment of the present invention will be described. Since the second embodiment is executed in a similar system to that in the first embodiment, constituent elements corresponding to those in the first embodiment have the same reference numerals and the detailed explanations of the elements will be omitted.  
         [0084]    In the above-described first embodiment, the electronic watermark detection processing is performed only on image data representing image and having a resolution higher than a predetermined resolution. In the second embodiment, the electronic watermark detection processing is performed on image data representing image without any condition.  
         [0085]    As in the case of the first embodiment, print information inputted from the DDI has three attributes, “text” indicative of font information, “graphics” indicative of figure vector, gradation information and the like, and “image” indicative of read photographic image or the like, and different functions are called for the respective attributes. Accordingly, it is easy to extract only the “image” attribute data upon reception of print information from the DDI and process the extracted data.  
         [0086]    It can be considered that generally, in a case where a bank note, a negotiable instrument or the like is to be duplicated, in order to reproduce an original image read by the scanner  300  or the like with fidelity, image data as the object of processing is inputted as “image” attribute data. In the second embodiment, it can be considered that if the counterfeit judgment processing is performed only on input image data, counterfeit prevention can be sufficiently realized.  
         [0087]    Next, the counterfeit judgment processing in the second embodiment will be described with reference to the flowchart of FIG. 8. In FIG. 8, process steps corresponding to those in FIG. 3 described in the first embodiment have the same step numbers, and the detailed descriptions of the steps will be omitted. Note that the counterfeit judgment processing is performed in the counterfeit judgment unit  2025  in the PDL driver  2023  or in the counterfeit judgment unit  2026  in the image driver  2024 , in the printer driver  2020 .  
         [0088]    In FIG. 8, at step S 802 , it is determined whether or not the input print information is image data. If the input information is image data, the process proceeds to step S 303  at which the electronic watermark detection processing is performed, while if the input information is not image data, the process proceeds to step S 306 , at which normal print processing is performed.  
         [0089]    Note that the counterfeit prevention processing in the second embodiment is the same as that as shown in FIG. 4 in the first embodiment.  
         [0090]    As described above, according to the second embodiment, the electronic watermark detection processing is performed only on image attribute data in the printer driver  2020 . By this arrangement, as the execution of the electronic watermark detection processing can be minimized, the counterfeit prevention function against counterfeiting bank notes, negotiable instruments and the like can be realized while preventing reduction of total throughput. &lt;Modification to Second Embodiment&gt;In the second embodiment, the counterfeit judgment processing is performed in accordance with whether or not input data is image data, however, the judgment reference can be further limited.  
         [0091]    [0091]FIG. 9 shows a flowchart of the counterfeit judgment processing in the counterfeit judgment unit  2026  in the PDL driver  2023  according to the present modification. The flowchart of FIG. 9 is different from the flowchart of FIG. 3 in that the determination as to whether or not the electronic watermark detection processing is performed is made at two steps S 902   a  and S 902   b . That is, if it is determined at step S 902   a  that the input data is image data, the amount of information per pixel (the number of bits) is checked at step S 902   b . Only if the amount of information is equal to or greater than that of respectively 8-bit RGB data, 24 bits, the process proceeds to step S 303  to perform the electronic watermark detection processing.  
         [0092]    Generally, even in case of image data, if the number of representable colors is small, i.e., the image data is indicative of monochrome image, 16-color image, 256-color image or the like, the probability of image data for counterfeiting is very low. Accordingly, the counterfeit judgment processing is omitted regarding image data with small number of representable colors, i.e., small amount of information, thereby processing time can be further reduced.  
         [0093]    Note that in the above-described first and second embodiments and the modifications, the present invention is applied to a color laser-beam printer, however, the printer to which the present invention is applicable is not limited to the color laser-beam printer, but the invention is applicable to other color printers such as an ink-jet printer and a thermal printer to form an image on a print medium based on other printing methods.  
         [0094]    Further, the criteria of judgment for execution of the counterfeit judgment processing is not limited to the above-described image data resolution, the image size, the image attribute or the information amount. Any other judgment reference can be employed as long as it can be used for judging whether or not input image data is in high quality for obtaining a printed output as a counterfeit.  
         [0095]    The present invention can be applied to a system constituted by a plurality of devices (e.g., a host computer, an interface, a reader and a printer) or to an apparatus comprising a single device (e.g., a copy machine or a facsimile apparatus).  
         [0096]    Further, the object of the present invention can be also achieved by providing a storage medium (or recording medium) storing software program code for realizing the functions of the above-described embodiments to a system or an apparatus, reading the program code with a computer (e.g., CPU, MPU) of the system or apparatus from the storage medium, then executing the program. In this case, the program code read from the storage medium realizes the functions according to the embodiments, and the storage medium storing the program code constitutes the invention. Furthermore, besides aforesaid functions according to the above embodiments are realized by executing the program code which is read by a computer, the present invention includes a case where an OS (operating system) or the like working on the computer performs a part or entire actual processes in accordance with designations of the program code and realizes functions according to the above embodiments.  
         [0097]    Furthermore, the present invention also includes a case where, after the program code read from the storage medium is written in a function expansion card which is inserted into the computer or in a memory provided in a function expansion unit which is connected to the computer, CPU or the like contained in the function expansion card or unit performs a part or entire actual process in accordance with designations of the program code and realizes functions of the above embodiments.  
         [0098]    As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

Technology Classification (CPC): 6