PRODUCTION OF TEST PRINTS FROM A FULL PAGE IMAGE BUFFER

Abstract: Apparatus for producing a document from electrical image signals includes a marking engine (12) for recording on a recording medium an image according to supplied electrical signals. An image processing unit (22) processes the electrical image signals according to a set of image processing parameter values and applies the processed electrical image signals to the marking engine. Electrical image signals are stored in memory (46), and the stored electrical signals are applied to the marking engine, without deleting the stored signals from the memory, to form a test print according to the set of image processing parameter values. The set of image processing parameter values are adjusted after a test print has been made, whereafter documents can be produced according to the new set of image processing parameter values by reapplying the stored electrical signals from the memory to the marking engine.

Description: PRODUCTION OF TEST PRINTS FROM A FULL PAGE IMAGE BUFFER BACKGROUND OF THE INVENTION Technical Field This invention relates generally to digital reproduction apparatus, and more particularly to such apparatus capable of processing an image signal to modify the reproduced image and to the production of test prints. Background Art There is an increasing demand for digital reproduction systems in which electrical signals that are representative of an original image are applied to a marking engine for forming an image on a recording medium. Many such systems include image processing functions for enhancing the image such as for example by adjusting density, contrast, color balance, etc. and/or by modifying the image content such as by scaling, merging, substituting colors, etc. After selecting desired image processing parameter values, an operator often wants to produce a test print eis a check on the correctness of the value settings. This is particularly important where a multi-page original set is to be reproduced and the operator needs to confirm that a particular page has been properly set up before advancing to the next page of the set. It has long been possible to make a test print by scanning an original document to produce electrical image signals, electronically processing the image signals to produce a test print, and, when satisfied with the image processing parameter value settings, re-scanning the original document for the production run. However, a copier's life is in part limited by the physical number of times the image is scanned, and the inconvenience of the operators is measured in part by the time duration they must wait to remove the original after pressing the start button. A copier which requires only a single scan per original document, regardless of the number of test prints required to obtain proper image processing parameter value settings, would be very preferable to a copier which requires two or more scans for the same functions. Some reproduction apparatus is known in which an operator is afforded an opportunity to view the resultant image on a video display before initiating a production run. See for example U.S. Patent No. 4,740,833, which issued on April 26, 1988 to K. Shiota et al. However, video displays do not offer true reproduction, particularly of color documents, and are therefore inferior to the production of a test print by the same technology as is to be used for the production run. Disclosure of Invention It is an object of the present invention to provide apparatus for reproducing an original document by a process which includes the production of one or more test prints without the need to scan the original document more than once. In accordance with one aspect of the present invention, apparatus is provided for producing a document from electrical image signals, including image forming means for recording on a recording medium an image according to supplied electrical signals. Image processing means process the electrical image signals according to a set of image processing parameter values and apply the processed electrical image signals to the image forming means. Electrical image signals are stored in memory, and the stored electrical signals are applied to the image processing means, without deleting the stored signals from the memory means, to form a test print according to the set of image processing parameter values. The set of image processing parameter values may be adjusted after a test print has been made, whereafter documents can be produced according to the new set of image processing parameter values by reapplying the stored electrical signals from the memory to the image processing means. The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below. Brief Description of the Drawings In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which: Figure 1 is a perspective view of a copier according to one embodiment of the present invention; Figure 2 is a schematic block diagram of the copier of Figure 1; Figure 3 is a schematic diagram of a portion of the copier of Figure 1; Figure 4 is a schematic block diagram of the image data path of the copier of Figure 1; and Figure 5 is a logic flow chart of the operation of the copier of Figure 1. Best Mode for Carrying Out the Invention The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. According to Figure 1, a copier 10 includes a marking engine 12 and a document scanner 14. Scanner 14 consists of an automatic document handler 16 for stream feeding multiple hard copy original documents past an optical system enclosed in an optics housing 18. Focused light reflected from an original document image is swept past a linear array of phototransducers, such as photodiodes or charge coupled devices, for scanning the image of an original document and converting the scanned image into electrical signals having values representative of the image density at associated pixel areas on the original document. As the scanning of the original document proceeds in a direction perpendicular to the row of pixel areas, a series of output signals from the transducers are repetitively loaded into an associated shift register and shifted out serially to provide a series of electrical signals having values representative of the image density of respective pixel areas in corresponding rows of pixel areas across the document image. Referring to Figure 2, the electrical signals from an imager 20 (which includes the phototransducer and associated electronics) may be manipulated by image processing electronics 22. Image processing electronics 22 will be discussed in more detail below with reference to Figure 4. The processed electrical signals are transmitted along an image data bus 24 to marking engine 12. Synchronization signals to identify different scan lines, and to provide page information and marking engine control, is transmitted along a job control communications link 26. Document scanner 14 also includes a control logic package 28 having an operator control panel 30 and digitizer 32. The control logic package is an interfacing medium for the operator to input functions and to receive messages from the reproduction apparatus. Setup instructions are input to the scanner, while information for finishing and processing of jobs will be sent to marking engine 12. The logic package consists of control software, interface software, and logic hardware. As way of example only, functions inputted by the operator at the control panel may include image editing features such as area erase (blanking and framing) , image shift, book copy modes, magnification, accent (spot) color, color substitution, positive-to-negative image reversal, forms overlay, highlighting, screening selected areas for breaking a continuous tone original into dots for reproduction as half-tone images, etc. The control logic package has a digital computer, preferably a microprocessor. Programming of a number of commercially available microprocessors is a conventional skill well understood in the art. This disclosure is written to enable a programmer having ordinary skill in the art to produce an appropriate control program for the microprocessor. The particular details of any such program would, of course, depend on the architecture of the designated microprocessor. Referring to Figure 3, control logic package 28 consists of temporary data storage memory 34, central processing unit 36, timing and cycle control unit 38, and stored program control 40. Data input and output is performed sequentially under program control. Input data are received from imager 20, and control signals are received from operator control panel 30 and digitizer 32 through an interrupt signal processor 42. The input signals are derived from various switches, sensors, and analog-to-digital converters. The output data and control signals are applied to the marking engine through image processing electronics 22. Digitizer 32 may take any of several well known forms such as the digitizing tablet disclosed in U.S. Patent No. 4,791,450, wherein an original is placed face up on the tablet. A stylus associated with the tablet is used by the operator to designate various positions on the original. Transducers located beneath the original produce signals relating the position of the positions touched relative to an edge of the tablet. Alternatively, the tablet may be of the known sonic type wherein a spark formed by a stylus creates sound waves in the air which are sensed by microphones placed along the sides of the tablet or wherein a sensor is placed in the stylus and sources at known points on the sides of the tablet emit sonic signals. Default machine setup instructions are stored in stored program control 40. An operator uses control panel 30 and digitizer 32 to input additional or alternative image processing parameter values for storage in temporary memory 34. Alternatively, setup instructions may be received via removable memory media from an off line computer, or the like. The setup instructions are used by image processing electronics 22 to modify the image data from imager 20, or are transmitted as control signals to marking engine 12. Preferably, imager 20 outputs a linearity corrected, D.C. level restored color image signal. The image signals first pass through a merge and scale unit 44 unmodified for storage in a full page image buffer 46. By "unmodified" it is meant in a form in which the image content of the original can be retrieved. If data from an incoming page is to be merged or overlayed with partial or full image signals stored in full page image buffer 46, the data in buffer 46 is fed back to merge and scale unit 44 along feedback paths 48 and 50 which are provided for windowed and page data, respectively. Merge and scale unit 44 is also capable of merging or overlaying the two feedback paths together. The unit can also scale the image. The color image data enters a color adjustment unit 52 and then a color substitution unit 54 from either merge and scale unit 44 or from image buffer 46 as determined by a selector unit 56. In color adjustment unit 52, the signal is acted upon to set color balance in response to operator settings of gain and offset controls. In color substitution unit 54, a designated color is substituted for an operator-identified color on the original. Operation of the reproduction apparatus will now be explained with reference to Figure 5. Using operator control panel 30 and digitizer 32, an operator selects desired image processing parameter values (step 60) and activates imager 20 to scan the image of the original document and convert the scanned image into electrical signals having values representative of the image density at associated pixel areas on the original document (step 62). The image data for the entire document page is stored in image buffer 46 (step 64) . To produce a test print according to the image processing parameter values selected, the image data is read from image buffer 46 and applied to the subsystems of image processing unit 22, without deleting the stored image data from buffer 46 (step 66) . If the test print is acceptable to the operator, the processed image signals are again sent to the marking engine for the production run without rescanning the original document; and the next original document is scanned, and so on. If, on the otherhand, the test print is unacceptable, the operator adjusts the image processing parameter values (step 68) and makes another test print is desired, again without rescanning the original document. It is clear from the above that the present invention provides apparatus for reproducing an original document by a process which includes the production of one or more test prints without the need to scan the original document more than once. Although the preferred embodiment has been described as a document copy machine, persons skilled in the art will readily appreciate that the invention is applicable to other types of reproduction apparatus, such as for example printers which receive image data in electronic form. The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims: Clai s; 1. Apparatus for producing a document from electrical image signals including image forming means 12 for recording on a recording medium an image according to supplied electrical signals; image processing means 22 for processing electrical image signals according to a set of image processing parameter values, and for applying the processed electrical image signals to said image forming means; and page memory means 46 for storing electrical image signals characterized by: means 56 for applying the stored electrical signals to said image processing means, without deleting the stored signals from said memory means, to form a test print according to the set of image processing parameter values; and means 52 for adjusting the set of image processing parameter values after a test print has been made, whereafter documents can be produced according to the adjusted set of image processing parameter values by reapplying the stored electrical signals from said memory means to said image processing means. 2. Apparatus as set forth in Claim 1 further characterized by said page memory means being adapted to store image signals in unmodified form. 3. Apparatus as set forth in Claim 1 further characterized by said image processing means including means for effecting image editing features. 4. Apparatus as set forth in Claim 3 further characterized by said image editing features including at least one of (a) area erase, (b) image shift, (c) book copy mode, (d) magnification, (e) accent color, (f) color substitution, (g) image reversal, (h) forms overlay, (i) highlighting, and (j) screening selected areas. 5. Apparatus as set forth in Claim 1 further characterized by said image processing means including means for effecting color adjustment to set color balance in response to operator settings. 6. An electronic copier for reproducing an original document including means 20 for scanning the original document image to convert its image to representative electrical signals; image forming means 12 for recording on a recording medium an image according to supplied electrical signals; image processing means 22 for processing electrical image signals according to a set of image processing parameter values, and for applying the processed electrical image signals to said image forming means; and page memory means 46 for storing electrical image signals characterized by: means 56 for applying the stored electrical signals to said image processing means, without deleting the stored signals from said memory means, to form a test print according to the set of image processing parameter values; and means 52 for adjusting the set of image processing parameter values after a test print has been made, whereafter documents can be produced according to the adjusted set of image processing parameter values by reapplying the stored electrical signals from said memory means to said image processing means without rescanning the original document. 7. An electronic copier as defined in Claim 6 further characterized by said page memory being adapted to store image signals in unmodified form. 8. An electronic copier as defined in Claim 6 further characterized by said image processing means including means for effecting image editing features. 9. An electronic copier as defined in Claim 8 further characterized by said image editing features including at least one of (a) area erase, (b) image shift, (c) book copy mode, (d) magnification, (e) accent color, (f) color substitution, (g) image reversal, (h) forms overlay, (i) highlighting, and (j) screening selected areas. 10. An electronic copier as defined in Claim 6 further characterized by said image processing means including means for effecting color adjustment to set color balance in response to operator settings.

Inventors: TELLE LAWRENCE BRUCE, TELLE, LAWRENCE, BRUCE
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1991
Main classification: H04N1
IPC codes: B41J29, H04N1