Image processing apparatus, and method of reversing color therein

Abstract: An image processing system for colour reversing, in which code data is received from a host computer via a reception buffer and analyzed. A logical operation is performed between bit patterns developed in bit-map RAM areas corresponding Y (yellow), M (magenta) and C (cyan) inks or toners and a bit pattern developed in a bit-map RAM area corresponding to a K (black) ink or toner, the K bit pattern is cleared, and the bit patterns of the Y, M and C bit-map areas that have been subjected to the logical operation are reversed, whereby an attractive color reversal is realized.

Description: This invention relates to an image processing apparatus and, more particularly, to an image processing apparatus capable of outputting reversed colors using Y (yellow), M (magenta), C (cyan) and K (black) colorants. The invention relates also to a method of reversing color in this image processing apparatus. In a conventional black-and-white binary printing apparatus in which a black-white reversal command is provided, a bit map within a designated range is reversed when the reversal command is received, whereby a black-white reversal is performed. In a case where a black-white reversal is applied to a multicolor printing apparatus, such as a Y (yellow)-, M (magenta)- and C (cyan)-three-color printing apparatus, as shown in Fig. 2, Y, M and C bit maps are as illustrated in (a) through (c) of Fig. 2, where the characters Y, M, C and K represent yellow, magenta, cyan and black, respectively. The Y, M and C bit maps following a simple reversal become as shown in (d) through (f) of Fig. 2, and the outputted result is depicted in (g) of Fig. 2. More specifically, merely by reversing each bit map, Y → M + C (blue), M → Y + C (green), C → Y + M (red), K → white, and background → Y + M + C (black) are obtained, and a color reversal based upon complementary colors is substantially achieved. However, when the above-described black-white reversal is applied, for example, to a YMCK four-color printing apparatus as shown in Fig. 3, merely reversing the Y, M, C and K-bit maps shown in (a) through (d) of Fig. 3 to provide the reversals of (e) through (h) of Fig. 3 and the output (i) of Fig. 3 results in Y → M + C + K (black), M → Y + C + K (black), C → Y + M + K (black), K → Y + M + C (black), and background → Y + M + C + K (black). Thus, a drawback is that all of the maps become pure black. A concern of the present invention is to provide an image processing apparatus, and a method of reversing color therein, in which a color reversal is made possible through a simple construction. An embodiment of the present invention provides an image processing apparatus capable of a wide variety of image editing, and in which picture quality at the time of a negative-positive reversal is improved. Japanese Patent Abstract JP-A-58214981 discloses a color output device in which a direct inversion can be carried out between color component signals. Similarly, Japanese Patent Abstract JP-A-1272267 discloses a picture processor in which color separated images of R, G and B can be inverted into the inverse of R, G and B respectively and converted by a conversion table converted into chrominance signals of Y, M and C. After this conversion the three chrominance signals are converted into four chrominance signals Y', M', C' and black for subsequent output. US Patent Specification No. US-A-4,788,535 also discloses signal processing apparatus in which color component signals can be directly inverted. All of these prior documents suffer from the problem which has been discussed in the preamble of this specification. In accordance with the present invention there is provided an image processing apparatus as set out in claim 1. In accordance with a second aspect of the present invention there is provided an image processing method as set out in claim 9. 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 or similar parts throughout the figures thereof. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a simplified block diagram illustrating the construction of a YMCK four-color printing apparatus according to first and second embodiments of the invention; Fig. 2 is a diagram for describing color-reversal processing in a conventional YMC three-color printing apparatus; Fig. 3 is a diagram for describing color-reversal processing in a conventional YMCK four-color printing apparatus; Fig. 4 is a flowchart illustrating color-reversal processing according to the first embodiment; Fig. 5 is a diagram showing Y, M, C and K bit maps according to the first embodiment; Figs. 6A and 6B show a flowchart illustrating color-reversal processing according to the second embodiment; Fig. 7 is a diagram showing Y, M, C and K bit maps according to the second embodiment; Fig. 8 is a simplified block diagram illustrating the construction of a YMCK four-color printing apparatus according to third and fourth embodiments of the invention; Fig. 9 is a flowchart illustrating color-reversal processing according to the third embodiment; Fig. 10 is a diagram showing Y, M, C and K byte maps according to the third embodiment; Figs. 11A and 11B show a flowchart illustrating color-reversal processing according to the fourth embodiment; and Fig. 12 is a diagram showing Y, M, C and K byte maps according to the fourth embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will now be described in detail with reference to the accompanying drawings. <First Embodiment> Fig. 1 is a block diagram illustrating the construction of a Y (yellow)-, M (magenta)-, C (cyan)-and K (black)-four-color printing apparatus according to first and second embodiments of the invention. As shown in Fig. 1, a YMCK four-color printing apparatus has a main body 1 connected to an external host computer 2 via a connector (not shown). The main body 1 is so adapted as to perform print-out upon receiving command data, which is indicative of a print instruction, color-reversal (i.e., negative-positive reversal) instruction and paper-discharge instruction, etc., from the host computer 2. The main body 1 includes a CPU 3 for performing overall control in accordance with various programs, described below, a reception buffer 4 for accumulating received data, such as data indicative of the print instruction, color-reversal instruction and paper-discharge instruction, etc., from the host computer 2, a ROM element 5 which stores a series of control procedures (programs) executed by the CPU 3, a RAM element 6 used as a working area when the CPU 3 executes programs, an output unit 7 which actually performs print-out, and a power-supply device, which is not shown. Negative-Positive reversal includes conversion from a negative image to a positive image and conversion from a positive image to a negative image. The output unit 7 is constituted by a color laser-beam printer, a color ink-jet printer or a color thermal-transfer printer, etc. It is permissible also to use a bubble-jet printer having a head of the type which jets droplets utilizing film boiling that relies upon thermal energy, as disclosed in the specification of USP 4,723,129. Bit-map areas 6a, 6b, 6c, 6d for the colors YMCK are defined within the RAM element 6, and bit patterns conforming to the input data are developed in respective ones of these areas. The processing executed by the printing apparatus 1 will now be described in accordance with the flowchart shown in Fig. 4. Logical operations (described below) such as AND, OR, NOT and X-OR (exclusive-OR) concerning each of the bit maps are executed by the CPU 3 in accordance with programs stored in the ROM element 5. When power is introduced to the apparatus, the CPU 3 first executes the processing of step S1, at which data from the host computer 2 is received and the received data is stored in the reception buffer 4. One unit code of data is read from the buffer 4. This is followed by the processing of step S2, at which the data read at step S1 is analyzed and processing branches to command processing which corresponds to the results of analysis. For example, processing branches to step S3 in case of a print instruction, to step S4 in case of a paper-discharge instruction, and to a step S5 in case of a color-reversal instruction. In case of a print instruction, the printing data is developed in the bit-map areas 6a, 6b, 6c, 6d of Y, M, C, K at step S3, after which the program returns to step S1. In case of the paper-discharge instruction, the printing data developed in the bit-map areas 6a, 6b, 6c, 6d of Y, M, C, K at step S3 is outputted to the output unit 7 in regular order to obtain a YMCK color print-out at step S4. In case of the color-reversal instruction, a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the Y bit map 6a at step S5. Similarly, a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the M bit map 6b at step S6, and a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the C bit map 6c at step S7. By virtue of the foregoing processing, the YMCK bit maps shown in Figs. 5(a) through (d) become as shown in Figs. 5(e) through (h). Next, the reversal designation area of the K bit map 6d is cleared at step S8, and the reversal designation area of the Y bit map 6a is reversed by a NOT operation at step S9. Similarly, the reversal designation area of the M bit map 6b is reversed by a NOT operation at step S10, and the reversal designation area of the C bit map 6c is reversed by a NOT operation at step S11. By virtue of the foregoing processing, the bit maps of the colors YMCK become as shown in Figs. 5(i) through (l). When the state of each bit map is outputted, the outputted result shown in Fig. 5(m) is obtained. Specifically, we have character Y → M + C (blue), character M → Y + C (green), character C → Y + M (red), character K → white, and background → Y + M + C (black), so that the desired color reversal is obtained. Thereafter, the program returns to step S1. In accordance with this embodiment, as described above, a logical operation is performed between each of the bit maps of Y, M, C and the bit map of K, after which the bit maps of Y, M and C are reversed. As a result, a highly attractive color reversal can be achieved. <Second Embodiment> A second embodiment of the present invention will now be described with reference to Figs. 6A, 6B and 7. The construction of the apparatus according to this embodiment is the same as in the first embodiment, and therefore reference should be had to Fig. 1 for the block diagram and contents thereof. Figs. 6A and 6B show a flowchart illustrating the processing procedure, and Fig. 7 shows the Y, M, C and K bit maps illustrating the results of processing. When power is introduced to the main body 1, the CPU 3 first executes the processing of step S1, at which data from the host computer 2 is received and the received data is stored in the reception buffer 4. One unit code of data is read from the buffer 4. This is followed by the processing of step S2, at which the data read at step S1 is analyzed and processing branches to command processing which corresponds to the results of analysis. For example, processing branches to step S3 in case of a print instruction, to step S4 in case of a paper-discharge instruction, and to a step S5 in case of a color-reversal instruction. In case of a print instruction, the printing data is developed in the bit-map areas 6a, 6b, 6c, 6d of Y, M, C, K at step S3, after which the program returns to step S1. In case of the paper-discharge instruction, the printing data developed in the bit-map areas 6a, 6b, 6c, 6d of Y, M, C, K at step S3 is outputted to the output unit 7 in regular order to obtain a YMCK color print-out at step S4. In case of the color-reversal instruction, a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the Y bit map 6a at step S5. Similarly, a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the M bit map 6b at step S6, and a reversal designation area in the K bit map 6d is written by an OR in a reversal designation area in the C bit map 6c at step S7. By virtue of the foregoing processing, the YMCK bit maps shown in Figs. 7(a) through (d) become as shown in Figs. 7(e) through (h). Next, the reversal designation area of the Y bit map is reversed by a NOT operation at step S9, the reversal designation area of the M bit map is reversed by a NOT operation at step S10, and the reversal designation area of the C bit map 6a is reversed by a NOT operation at step S11. Step S12 calls for the reversal designation area of the Y bit map to be copied onto the reversal designation area of the K bit map. Thus, the maps of Y, M, C and K are as illustrated in (i) through (l) of Fig. 7. Next, at step S13, the reversal area in the M bit map 6b is written by an AND operation in the reversal area of the K bit map 6. Similarly, the reversal designation area in the C bit map 6c is written by an AND operation in the reversal designation area of the K bit map 6 at step S14. Thus, the K bit map 6d becomes as shown in Fig. 7(p). This is followed by step S15, at which the conversion designation area in the K bit map 6d is written by an XOR operation in the reversal designation area in the Y bit map 6a. Then, at step S16, the conversion designation area in the K bit map 6d is written by an XOR operation in the reversal designation area in the M bit map 6b. Next, the conversion designation area in the K bit map 6d is written by an XOR operation in the reversal designation area in the C bit map 6c. Thus, the Y, M and C bit maps become as depicted in Figs. 7(m) through (o). By virtue of the foregoing processing, Fig. 7(q) is obtained when the Y, M, C and K bit maps are outputted, and we have character Y → M + C (blue), character M → Y + C (green), character C → Y + M (red), character K → white, and background → K (black), so that the desired color reversal is obtained. Thereafter, the program returns to step S1 and the apparatus awaits for receipt of data. In accordance with the second embodiment described above, the K bit map is reconstructed by the results of the logical operations applied to the Y, M and C bit maps, and logical operations are performed between the K bit map each of the Y, M and C bit maps. As a result, a highly attractive color reversal can be achieved. It should be noted that whereas a reversed result which does not employ the K (black) bit map is obtained in the first embodiment described above, the reversal in the second embodiment employs the K (black) bit map in addition to the other bit maps, and therefore color reproducibility is further enhanced. Further, it is permissible for the reversal designation areas to be designated by a command or to be handled as bit maps in their entirety. Moreover, it is permissible for the logical operations such as OR, AND and XOR to be implemented by hardware, in which case execution speed is raised. <Third Embodiment> A third embodiment of a multivalued printing apparatus according to the present invention will be described with reference to Figs. 8, 9 and 10. Fig. 8 is a block diagram illustrating the construction of a Y (yellow)-, M (magenta)-, C (cyan)-and K (black)-four-color printing apparatus according to third and fourth embodiments of the invention. As shown in Fig. 1, a YMCK four-color printing apparatus has a main body 21 connected to an external host computer 22 via a connector (not shown). The main body 1 is so adapted as to perform print-out upon receiving command data, which is indicative of a print instruction, color-reversal instruction and paper-discharge instruction, etc., from the host computer 22. The main body 1 includes a CPU 23 for performing overall control in accordance with various programs, described below, a reception buffer 24 for accumulating received data, such as data indicative of the print instruction, color-reversal instruction and paper-discharge instruction, etc., from the host computer 22, a ROM element 25 which stores a series of control procedures (programs) executed by the CPU 23, a RAM element 26 used as a working area when the CPU 23 executes programs, a YMCK multivalued output unit 27 which actually performs print-out, and a power-supply device, which is not shown. Byte-map areas 26a, 26b, 26c, 26d for the colors YMCK are defined within the RAM element 26, and byte patterns conforming to the input data are developed in respective ones of these areas. Numeral 28 denotes a control panel provided on the printer and having negative-positive reversal key 29 which is used so that entry can be gained to the flow of a negative-positive reversal, described below, manually on the printer side. The processing executed by the printing apparatus 21 will now be described in accordance with the flowchart shown in Fig. 9. When power is introduced to the main body 21, the CPU 23 first executes the processing of step S1, at which data from the host computer 22 is received and the received data is stored in the reception buffer 24. One unit code of data is read from the buffer 24. This is followed by the processing of step S2, at which the data read at step S1 is analyzed and processing branches to command processing which corresponds to the results of analysis. For example, processing branches to step S3 in case of a print instruction, to step S4 in case of a paper-discharge instruction, and to a step S5 in case of a color-reversal instruction. In case of a print instruction, the printing data is developed in the byte-map areas 26a, 26b, 26c, 26d of Y, M, C, K at step S3, after which the program returns to step S1. In case of the paper-discharge instruction, the printing data developed in the byte-map areas 26a, 26b, 26c, 26d of Y, M, C, K at step S3 is outputted to the YMCK multivalued output unit 27 in regular order to obtain a YMCK color multivalued print-out at step S4. In case of the color-reversal instruction, the value of a reversal designation area in the Y byte map 26a and the value of a reversal designation area in the K byte map 26d are compared at step S5, and the larger value is written in the reversal designation area in the Y byte map 26a. Similarly, the value of a reversal designation area in the M byte map 26b and the value of a reversal designation area in the K byte map 26d are compared at step S6, and the larger value is written in the reversal designation area in the M byte map 26b. Further, the value of a reversal designation area in the C byte map 26c and the value of a reversal designation area in the K byte map 26d are compared at step S7, and the larger value is written in the reversal designation area in the C byte map 26c. By virtue of the foregoing processing, the YMCK byte maps shown in Figs. 10(a) through (d) become as shown in Figs. 10(e) through (h). Next, the reversal designation area of the K byte map 26d is cleared at step S8, and the reversal designation area of the Y byte map 26a is reversed by a NOT operation at step S9. Similarly, the reversal designation area of the M byte map 26b is reversed by a NOT operation at step S10, and the reversal designation area of the C byte map 26c is reversed by a NOT operation at step S11. By virtue of the foregoing processing, the byte maps of the colors YMCK become as shown in Figs. 10(i) through (l). When the state of each byte map is outputted, the outputted result shown in Fig. 10(m) is obtained. Specifically, we have character Y (Y255, M0, C0, K0) → blue (Y0, M255, C255, K0); character M (Y0, M255, C0, K0) → green (Y255, M0, C255, K0); character C (Y0, M0, C255, K0) → red (Y255, M255, C0, K0); character K (Y0, M0, C0, K255) → white (Y0, M0, C0, K0); and background → (Y0, MO, CO, K0) → black (Y255, M255, C255, K0). Thus the desired color reversal is obtained. The program then returns to step S1. Thus, in accordance with the third embodiment, as described above, the values of each of the Y, M and C byte maps are compared with the value of the K byte map and the larger values are written, after which the Y, M, C and K maps are reversed. As a result, a highly attractive color reversal can be realized. <Fourth Embodiment> A fourth embodiment of the present invention will now be described with reference to Figs. 11A, 11B and 12. The construction of the apparatus according to this embodiment is the same as in the third embodiment, and therefore reference should be had to Fig. 8 for the block diagram and contents thereof. Figs. 11A and 11B show a flowchart illustrating the processing procedure, and Fig. 12 shows the Y, M, C and K byte maps illustrating the results of processing. When power is introduced to the main body 21, the CPU 23 first executes the processing of step S1, at which data from the host computer 22 is received and the received data is stored in the reception buffer 24. One unit code of data is read from the buffer 4. This is followed by the processing of step S2, at which the data read at step S1 is analyzed and processing branches to command processing which corresponds to the results of analysis. For example, processing branches to step S3 in case of a print instruction, to step S4 in case of a paper-discharge instruction, and to a step S5 in case of a color-reversal instruction. In case of a print instruction, the printing data is developed in the byte-map areas 26a, 26b, 26c, 26d of Y, M, C, K at step S3, after which the program returns to step S1. In case of the paper-discharge instruction, the printing data developed in the byte-map areas 26a, 26b, 26c, 26d of Y, M, C, K at step S3 is outputted to the YMCK multivalued output unit 27 in regular order to obtain a YMCK color multivalued print-out at step S4. In case of the color-reversal instruction, the value of a reversal designation area in the K byte map 26d is added to a reversal designation area in the Y byte map 26a at step S5. Similarly, the value of the reversal designation area in the K byte map 26d is added to a reversal designation area in the M byte map 26b at step S6, and the value of the reversal designation area in the K byte map 26d is added to a reversal designation area in the C byte map 26c at step S7. By virtue of the foregoing processing, the YMCK byte maps shown in Figs. 12(a) through (d) become as shown in Figs. 12(e) through (h). Next, the reversal designation area of the Y byte map is reversed by a NOT operation at step S8, the reversal designation area of the M byte map 26b is reversed by a NOT operation at step S9, and the reversal designation area of the C byte map 26c is reversed by a NOT operation at step S10. Step S11 calls for the value of the reversal designation area of the Y byte map 26a to be copied onto the reversal designation area of the K byte map 26d. Thus, the maps of Y, M, C and K are as illustrated in (i) through (l) of Fig. 12. Next, at step S12, the value of the reversal area in the K byte map 26d and the value of the reversal area of the byte map 26b are compared, and the smaller value is written in the reversal area in the K byte map 26d. Similarly, the value of the reversal area in the K byte map 26d and the value of the reversal area of the C byte map 26c are compared, and the smaller value is written in the reversal area in the K byte map 26d at step S13. Thus, the K byte map 26d becomes as shown in Fig. 12(p). This is followed by step S14, at which the value of the K byte map 26d is subtracted from the value of the conversion designation area in the Y byte map 26a, then by step S15, at which the value of the K byte map 26d is subtracted from the value of the conversion designation area in the M byte map 26b, and then by step S16, at which the value of the K byte map 26d is subtracted from the value of the conversion designation area in the C byte map 26c. Thus, the Y, M, C and K byte maps become as depicted in Figs. 12(m) through (p). By virtue of the foregoing processing, Fig. 11(q) is the result when the Y, M, C and K byte maps obtained are outputted. Specifically, we have character Y (Y255, M0, C0, K0) → blue (Y0, M255, C255, K0); character M (Y0, M255, C0, K0) → green (Y255, MO, C255, K0); character C (Y0, M0, C255, K0) → red (Y255, M255, C0, K0); character K (Y0, M0, C0, K255) → white (Y0, M0, C0, K0); and background → (Y0, MO, CO, K0) → black (Y255, M255, C255, K0). Thus the desired color reversal is obtained. Following the foregoing, the program returns to step S1 and the apparatus awaits for receipt of data. In accordance with the fourth embodiment described above, the value of the K byte map is added to each of the Y, M and C byte maps, after which the Y, M and C byte maps are reversed and the Y byte map is copied onto the K byte map. The C and M byte maps are then each compared with the K byte map, and the smaller values are written in the K byte map, after which the value of the K byte map is subtracted from the values of the Y, M and C byte maps. As a result, a highly attractive reversal can be achieved. In the foregoing embodiments, the logical operations for negative-positive reversal are executed by a CPU. However, a hardware arrangement composed of a gate array or the like can be used to implement the logical operations if desired. This will make it possible to speed up processing. The function for the negative-positive reversal may be provided on the side of the host computer. More specifically, an arrangement can be adopted in which software for executing the negative-positive reversal method of the present invention is stored on a magnetic recording medium and the above-mentioned host computer is made to execute the reversal method by the software. In addition, the output unit (printer) 7 may be made independent from the processor which executes the negative-positive reversal of the invention. Further, the source of the plural color-component signals produced can be code data sent from the host computer, or the source can be image data. The color components of an image may be R, G, B; Y, M, C; or M, C, K. Thus, in accordance with the embodiments described above, it is possible to provide a multicolor printing apparatus capable of performing a high-quality color reversal through a simple construction. As many apparently widely different embodiments of the present invention can be made without departing from the 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.

Claims: An image processing apparatus capable of performing negative-positive reversal on a plurality of color component data signals representing an original image, the apparatus comprising: means (3, 23) for generating a plurality of color component data signals including a black component signal; means (3, 22) for inverting; and output means (7, 27) for outputting a reversed image of said original image; and characterised by the inverting means being adapted to carry out inversion after a logical or arithmetic operation has been performed between the black color component signal and each of the other color component signals in which information from said black color component signal is introduced into each of said other component signals, said output means being adapted to produce said reversed image from the result of the previous logical or arithmetic operation and the inversion carried out by said inverting means. Apparatus according to claim 1, wherein the plurality of color component data signals are yellow (Y), magenta (M), cyan (C) and black (K) signals, and further comprising respective Y, C, M and K memories (6A, 6B, 6C, 6D), said inverting means being adapted to develop said color component signals into their respective memories and to designate areas of said Y, C, M and K memories as reversal designation areas. Apparatus according to claim 2, wherein said inverting means are adapted firstly to write by an OR command the reversal designation area of the K memory into the reversal designation areas of the Y, C and M memories; and secondly to clear the reversal designation area of the K memory and reverse the reversal designation areas of the Y, C and M memories by a NOT logical operation whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. Apparatus according to claim 2, wherein said inverting means are adapted firstly to write by a logical OR operation the reversal designation area of the K memory into the reversal designation areas of the Y, C and M memories; secondly to reverse the reversal designation areas of the Y, M and C memories by a logical NOT operation; thirdly to copy the reversal designation area of the Y memory into the reversal designation area of the K memory; fourthly to write by a logical AND operation the reversal areas in the M and C memories into the reversal designation area of the K memory; and fifthly to write by a logical XOR operation the reversal designation area of the K memory into the reversal designation areas of the Y, M and C memories; whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. Apparatus according to claim 2, wherein said inverting means is adapted firstly to compare the values of the reversal designation areas in the Y, M and C memories with the value of the reversal designation area in the K memory and to write the larger value for each of these comparisons in the respective reversal designation areas of the Y, M and C memories; secondly to clear the reversal designation area in the K memory and to reverse by a logical NOT operation the reversal designation areas of the Y, M and C memories; whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. Apparatus according to claim 2, wherein said inverting means is adapted firstly to add the reversal designation area of the K memory to the respective reversal designation areas of the Y, M and C memories; secondly to reverse by a logical NOT operation the reversal designation areas of the Y, M and C memories; thirdly to copy the reversal designation area of the Y memory into the reversal designation area of the K memory; fourthly to compare the value of the reversal designation area of the K memory with the respective reversal designation areas of the M and C memories and to write the respective smaller values resulting from these comparisons into the K memory; and fifthly to subtract the designated reversal area of the K memory from each of the designated reversal areas of the Y, M and C memories whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. Apparatus according to any one of the preceding claims, wherein the Y, M, C and K memories are either bit map or byte map memories. Apparatus according to any one of the preceding claims, wherein the output means comprise either a laser beam printer or an ink jet printer. An image processing method of performing negative-positive reversal on a plurality of color component data signals representing an original image, the method comprising: generating a plurality of color component data signals including a black component signal; inverting; and outputting a reversed image of said original image; and characterised by the inverting step carrying out inversion after a logical or arithmetic operation has been performed between the black color component signal and each of the other color component signals in which information from said black color component signal is introduced into each of said other component signals, the reversed image output in the outputting step being produced by the result of the previous logical or arithmetic operation and the inversion carried out by said inverting step. A method according to claim 9, wherein the plurality of color components are yellow, magenta, cyan and black. A method according to claim 10, wherein the Y, C, M and K color component data signals are developed in respective Y, C, M and K memories, with areas of said Y, C, M and K memories being designated as reversal designation areas. A method according to claim 11, wherein firstly the reversal designation area of the K memory is written (Fig 4: S5-S7) by an OR command in the reversal designation areas of the Y, C and M memories; and secondly the reversal designation area of the K memory is cleared (Fig 4: S8) and the reversal designation areas of the Y, C and M memories are reversed by a NOT logical operation whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white, and the background becomes black. A method according to claim 11, wherein firstly the reversal designation area of the K memory is written (Fig 6A: S5-S7) by a logical OR operation into the reversal designation areas of the Y, C and M memories; secondly the reversal designation areas of the Y, M and C memories are reversed (Fig 6A, S9-S11) by a logical NOT operation; thirdly the reversal designation area of the Y memory is copied (Fig 6B: S12) into the reversal designation area of the K memory; fourthly the reversal areas in the M and C memories are written (Fig 6B: S13, S14) by a logical AND operation into the reversal designation area of the K memory; and fifthly the reversal designation area of the K memory is written (Fig 6B: S15-S17) by a logical XOR operation into the reversal designation areas of the Y, M and C memories; whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. A method according to claim 11, wherein the values of the reversal designation areas in the Y, M and C memories are each compared (Fig 9: S5-S7) with the value of the reversal designation area in the K memory and the larger value for each of these comparisons is written in the respective reversal designation areas of the Y, M and C memories; secondly the reversal destination area in the K memory is cleared (Fig 9: S8) and the reversal designation areas of the Y, M and C memories are reversed (Fig 9: S9-S11) by a logical NOT operation; whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. A method according to claim 11, wherein firstly the reversal designation area of the K memory is added (Fig 11A: S5-S7) to the respective reversal designation areas of the Y, M and C memories; secondly the reversal designation areas of the Y, M and C memories are reversed (Fig 11A: S8-S10) by a logical NOT operation; thirdly the reversal designation area of the Y memory is copied (Fig 11B: S11) into the reversal designation area of the K memory; fourthly the value of the reversal designation area of the K memory is compared (Fig 11B: S12,S13) with the respective reversal designation areas of the M and C memories and the respective smaller values resulting from these comparisons are written in the K memory; and fifthly the designated reversal area of the K memory is subtracted (Fig 11B: S14-S16) for each of the designated reversal areas of the Y, M and C memories, whereby in the final image characters originally in the Y memory become blue, characters originally in the M memory become green, characters originally in the C memory become red, characters originally in the K memory become white and the background becomes black. A method according to any one of claims 11 to 15, wherein the Y, M, C and K memories are either bit map or byte map memories. A method according to any one of claims 9 to 16, including forming the reversed image on a medium by a printer. A method according to claim 17, wherein the printer is either a laser beam printer or an ink jet printer.

Inventors: ONODERA KEN, ONODERA, KEN
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1991
Main classification: G06K15
IPC codes: H04N1, B41J5, B41J2, G03G15, G06K15, G03F3