JP2006157480A - Image processing apparatus and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a dot pattern that is additional information from being added to a white portion of printed paper. <P>SOLUTION: This image processing apparatus is characterized by including: a detection means for detecting a change in a received image signal; a storage means for storing information on the basis of the detection by the detection means; and an adding means for adding the additional information to the image signal on the basis of the information stored by the storage means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and method having a function of adding additional information to an input image.

  In recent years, the performance of image recording apparatuses such as color printers and color copying machines has improved, and high-quality images can be formed on paper. Under such circumstances, securities such as banknotes may be counterfeited, and various anti-counterfeit technologies have been considered.

FIG. 10 shows a conventional method for adding additional information such as an encrypted engine ID. This information is composed of a dot pattern. Reference numeral 501 denotes a BD signal that is an output signal of a detection sensor that detects the start position of the exposure beam in the main scanning direction. Reference numeral 505 denotes an image formation permission signal, that is, a signal for forming an image in the horizontal direction. Reference numeral 503 represents additional information. From the content described in Patent Document 1 for the purpose of preventing counterfeiting, the conventional dot pattern addition method adds additional information in synchronization with the image formation permission signal of FIG.
JP-A-10-304179

  However, the conventional technique has the following problems.

  If a dot pattern is always added while the image formation permission signal is in an enabled state, a dot pattern is also added to the white paper portion of the paper. When the dot pattern is added in yellow, the white paper portion of the printed paper appears yellowish.

  An object of the present invention is to provide an image processing apparatus and an image processing method that suppress deterioration in image quality due to the addition of the dot pattern.

  In order to achieve the above object, the present invention is based on detection means for detecting a change in an input image signal, storage means for storing information based on detection by the detection means, and information stored by the storage means. Adding means for adding additional information to the image signal.

  By adding additional information composed of dot patterns using an image signal sent from the controller as a trigger, it is possible to prevent the blank portion of the paper on which the image is printed from appearing yellowish.

(First embodiment)
In the first embodiment, when there is a change such that the Y (yellow) image signal output from the controller rises or falls, additional information such as an encrypted engine ID composed of a dot pattern is added. The configuration will be described. In this embodiment, it is assumed that image signals input from an external computer or the like are sent in frame sequential order in M (magenta), C (cyan), Y (yellow), and BK (black). The density level is represented by 8 bits. A recognition signal added to these image signals is called an add-on dot. In the present embodiment, the recognition signal is added only to the Y (yellow) image signal. This is based on the fact that among the above colors, the yellow image is most difficult to be identified by human eyes. As a result, even if a recognition signal is added and printing is performed, it is not necessary to substantially deteriorate the image quality from the original image. FIG. 2 shows a color image recording apparatus used in each embodiment of the present invention.

  First, the charging drum 101 uniformly charges the photosensitive drum 100 to a predetermined polarity, and a magenta first latent image, for example, is formed on the photosensitive drum 100 by exposure with the laser beam L. Next, in this case, a required developing bias voltage is applied only to the magenta developing device Dm to develop the magenta latent image, and a magenta first toner image is formed on the photosensitive drum 100.

  On the other hand, the transfer paper P is fed at a predetermined timing, and immediately before the leading edge reaches the transfer start position, a transfer bias voltage (+1.8 KV) having a polarity opposite to that of the toner (for example, plus polarity) is applied to the transfer drum 102. Then, the first toner image on the photosensitive drum 100 is transferred to the transfer paper P, and the transfer paper P is electrostatically attracted to the surface of the transfer drum 102. Thereafter, the magenta toner remaining on the photosensitive drum 100 is removed by the cleaner 103 to prepare for the next color latent image forming and developing step.

  Next, a second cyan latent image is formed on the photosensitive drum 100 by the laser beam L, and then the second latent image on the photosensitive drum 100 is developed by the cyan developing device Dc. The second toner image is formed. The cyan second toner image is transferred onto the transfer paper P in accordance with the position of the first magenta toner image transferred onto the transfer paper P. In transferring the second color toner image, a bias voltage of +2.1 KV is applied to the transfer drum 102 immediately before the transfer paper reaches the transfer portion.

  Similarly, the third and fourth latent images of yellow and black are sequentially formed on the photosensitive ram 100, and each is developed sequentially by the developing devices Dy and Db, and transferred to the transfer paper P first. The third and fourth toner images of yellow and black are sequentially transferred in alignment with the toner image, and thus, the four color toner images are formed on the transfer paper P in an overlapping state.

  FIG. 3 is a diagram illustrating a flow of signal processing according to the first embodiment.

  In FIG. 3, the host 201, the controller 202, and the engine 203 have independent main control units (CPUs) for controlling each block in each device. That is, the host 201 has a CPU 2010, the controller 202 has a CPU 2020, and the engine 202 has a CPU 2030. Each CPU controls the operation timing in each machine and communication between each device via a bus (not shown). ing.

  In general, in general, an image processing apparatus such as a laser beam printer used in the present embodiment often includes a controller unit and an engine unit separately. For this reason, it is usually configured such that each device is closed so that each device is individually controlled.

  RGB image signals are sent in parallel from the host 201 and input to the controller 202. Also, several types of halftone processing can be selected and instructed from the host 201, and the user selects one from the predetermined operation unit of the host 201 at the time of printing, and the selected halftone number is the halftone instruction. A signal is sent to the controller 202.

  In the present embodiment, a halftone instruction signal is input to the controller 202 through a signal line dedicated to a control signal that is different from the dedicated line for image signals. As a result, signals can be exchanged independently of transmission / reception of image signals, and the degree of freedom of signal transmission / reception timing is increased.

  However, the present invention is not limited to this, and a halftone instruction signal may be input as a parallel command via the same data line as the image signal.

  In the controller 202, a CPU 2020, a color conversion processing unit 204, a γ correction unit 205, and a halftone processing unit 206 are arranged. The input RGB signal is subjected to masking and UCR processing by the color conversion processing unit 204, color correction and under color removal are performed, and magenta (M), cyan (C), yellow (Y), black (BK) ) Image signal.

  As described above, the image recording apparatus prints one screen for each of the colors Y, M, C, and BK (in the surface sequence). Image signals are output in the order of data for one screen, data for one screen of Y, and data for one screen of BK.

  Next, correction is performed by the γ correction unit 205 so that the output density curve becomes linear, and the correction is input to the halftone processing unit 206.

  On the other hand, a halftone instruction signal is input to the halftone processing unit 206 in parallel with this. A halftone processing unit 206 processes image data input in accordance with a halftone instruction signal.

  After the above processing is performed by the controller 202, M, C, Y, and BK image signals are input to the engine 203.

  The engine 203 includes a CPU 2030, a dot pattern addition processing unit 207, a PWM processing unit 208, and a laser driving unit 209. Only when the input image signal is yellow, the dot pattern addition processing unit 207 adds a dot pattern. Thereafter, the PWM processor 208 applies pulse width modulation. The halftone instruction signal described above is input to the engine 203 by a serial command or the like at the same time as being input to the halftone processing unit 206, and is input to the PWM processing unit 208. The PWM processing unit 208 performs PWM processing according to the input halftone instruction signal, and the modulated PWM signal is input to the laser driving unit 209 and printed.

  Next, the dot pattern will be described.

  FIG. 5 shows an example dot pattern used in the first embodiment. This dot pattern is composed of 3 dots in the horizontal direction and 4 dots in the vertical direction. The part displayed in black is the part where dots are forcibly added, and the part displayed in white is forced. This is the part where dots are not added. Although the dot pattern as shown in FIG. 5 is used in this patent, the dot pattern may have other forms.

  Next, additional information composed of dot patterns will be described.

  FIG. 6 shows additional information such as an engine ID encrypted using the dot pattern 504 of FIG. This has an arbitrary width in each of the sub-scanning direction and the main scanning direction. In this patent, for example, a width of 200 dots in the sub scanning direction and a width of 100 dots in the main scanning direction is assumed. Where the dot pattern 504 is arranged is determined by the engine ID or the like, and the arrangement does not change unless the engine is changed.

  Next, the operation of the dot pattern addition processing unit 207 and a method for adding additional information such as an encrypted engine ID will be described.

  FIG. 4 is an internal block diagram of the dot pattern addition processing unit 207. The CPU 2030 reads information such as an encrypted engine ID stored in the EEPROM 401 and outputs the information to the dot pattern addition processing unit 207. The additional information generation unit 409 determines whether to add a dot or not. The dot pattern addition circuit 410 adds the signal sent from the additional information generation unit 409 to the image signal sent from the controller using a logic circuit such as AND or OR. The main scanning counter 404 counts the HIGH period of the BD signal using the clock signal CLK, and is initialized when the BD signal falls. The count value is sent to the additional information generation unit 409. The sub-scanning counter 405 starts counting of the sub-scanning counter 405 from the time point when the change of the image signal is detected in a state where the count value of the sub-scanning counter 405 is 0, and counts how many times the LOW period of the BD signal has come. . The count value is initialized when the additional information 503 is formed in the sub-scanning direction. The count value is sent to the additional information generation unit 409. The information from the CPU 2030 input to the dot pattern addition processing unit is parity-checked by the parity check 406. If there is an error, the printing operation is stopped.

  FIG. 7 is a diagram illustrating an example of the formation start position of the additional information 503. The timing when the BD signal 501 rises when the count value of the sub-scanning counter 403 is 0 and the image signal 502 rises when the image formation permission signal 505 is permitted, for example, 5 which is the value of the counter value 506 of the main scanning counter 404. The additional information generation unit 409 stores the information. If this point is used as the formation start position of the additional information in the main scanning direction and the image signal changes after the 100-dot additional information is formed in the main scanning direction, that position is used as the main scanning direction of the second additional information. The formation start position at. The above is repeated every time 100 dots of additional information are formed in the main scanning direction. However, if there is a change b in the image signal while forming the additional information, the change in the image signal is ignored.

  FIG. 1 shows an example of a method for adding additional information 503 composed of dot patterns 504 in synchronization with changes in the image signal. a, b, c, d, e, and f represent changed image signals. The additional information 503 is added from the main scanning position where the count value 506 of the main scanning counter 404 described in FIG. 7 is 5 while the count value of the sub scanning counter is not 0. The number of dots in the main scanning direction 100 dots of the additional information to forcibly add a dot or not to forcibly add a dot is based on information such as the encrypted engine ID from the CPU 2030 and the dot pattern 504. Judgment. A signal for forcibly adding dots or not forcibly adding dots is sent to the dot pattern addition circuit 410.

  In this patent, since the additional information is composed of 200 dots in the sub-scanning direction, the additional information is formed until the count value of the sub-scanning counter 405 reaches 200. When the count value of the sub-scanning counter reaches 200, it is initialized to 0, and if there is a change d in the image signal again, that position is set as the additional information formation start position, and then additional information is added. Subsequent control repeats the above.

  By performing the above control, a dot pattern is not added to a place where there is no image on the paper, and it is possible to prevent the printed white paper portion from appearing yellowish.

(Second Embodiment)
In the second embodiment, a description will be given of a configuration in which constant section additional information is added when there is a change such that an image signal rises or falls. In the first embodiment, only one piece of additional information is added to the change in the image signal, whereas in the second embodiment, fixed section additional information is added in each of the main scanning direction and the sub-scanning direction.

  FIG. 8 shows an example of adding three pieces of additional information in the main scanning direction and two pieces of additional information in the sub scanning direction when the image signal changes. g, h, i. j represents a change in the image signal. When the BD signal 501 rises and the image formation permission area signal 505 is enabled and the image signal 502 changes, the following points are changed in the method of the first embodiment, and additional information is sub-scanned in the main scanning direction by three. Add two in the direction. In the second embodiment, since three additional information is added in the main scanning direction, 300 dots are added from the additional information formation start position in the main scanning direction when the sub-scanning counter is 0. Initialization of the sub-scanning counter is performed after the count value of the sub-scanning counter reaches 400 because two additional information are formed in the sub-scanning direction. The additional information is initialized every time 100 dots are added in the main scanning direction, and is initialized every time 200 dots are added in the sub scanning direction. Similarly to the first embodiment, if there is a change h in the image signal while adding additional information in the main scanning direction, the signal is ignored. In the present embodiment, the fixed section is described with specific numbers, but the fixed section is arbitrary.

  When the above control is finished and the change i of the image signal comes again, the above control is performed again, so that the dot pattern to the place where there is no image on the paper is almost eliminated, and a certain section is added. Since the additional information is hardened, the decoding is easier than in the first embodiment.

(Third embodiment)
In the third embodiment, a configuration in which one or a plurality of additional information is added from the rising edge of the image formation permission area will be described.

  FIG. 9 shows an example of adding a plurality of additional information composed of dot patterns from the rise of the image formation permission signal 505 for the next line when there is a change in the image signal.

  Only differences from the first and second embodiments will be described. When the image signal changes, when the count value of the next line, that is, the sub-scanning counter 405 is incremented and the image formation permission signal 505 rises, one or more additional information is added based on information sent from the CPU 2030 from that timing. Append. The addition start position of the additional information is the same as the addition method of the first embodiment and the second embodiment except that the additional information starts from the rising edge of the image permission signal.

  With the above configuration, it is almost impossible to add a dot pattern to a portion where there is no image, and since the addition start position of the additional information is the same, decoding is easier than in the first embodiment.

(Other embodiments)
Note that the present invention can be applied to a system (for example, a copier, a facsimile machine, etc.) consisting of a single device even when applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.). It may be applied.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. It goes without saying that a part of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

  Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

The figure which shows the addition method of the additional information in 1st Embodiment. The figure which shows the structure of the printing part of a color image forming apparatus. Diagram showing the flow of signal processing Internal block diagram of the dot pattern addition processing unit The figure which shows the example of a dot pattern in 1st Embodiment The figure which shows the example of additional information comprised with the dot pattern of FIG. The figure which shows additional information and a dot pattern formation start position The figure which shows the addition method of the additional information in 2nd Embodiment. The figure which shows the addition method of the addition payment in 3rd Embodiment The figure which shows the conventional addition method of the additional information which consists of the dot pattern

Claims (11)

Detection means for detecting changes in the input image signal;
Storage means for storing information based on detection by the detection means;
An image processing apparatus comprising: addition means for adding additional information to the image signal based on information stored in the storage means.   2. The storage device according to claim 1, wherein when the detection unit performs detection while the additional information is added to the image signal, the storage unit does not store the timing at which the change of the image signal is detected. The image processing apparatus described.   The image processing apparatus according to claim 1, wherein the additional information is added to the image signal from a timing at which the detection unit detects a change in the image signal.   The image forming apparatus according to claim 1, wherein the additional information is repeatedly added to the image signal a plurality of times.   After the detection means detects the change in the image signal, the additional information is added to the image signal from the timing at which the signal of the image formation permission signal indicating the predetermined image formation range in the main scanning direction changes. The image forming apparatus according to claim 1, wherein: A detection process for detecting changes in the input image signal;
A storage step for storing information based on detection by the detection step;
An image processing method comprising: an additional step of adding additional information to the image signal based on the information stored in the storage step.   7. The method according to claim 6, wherein when the detection step is performed while the additional information is added to the image signal, the storage step does not store the timing at which the change in the image signal is detected. The image processing method as described.   The image processing method according to claim 6, wherein the additional information is added to the image signal from a timing at which the detection step detects a change in the image signal.   The image processing method according to claim 6, wherein the additional information is repeatedly added to the image signal a plurality of times.   After the detection step detects the change in the image signal, the additional information is added to the image signal from the timing at which the signal of the image formation permission signal indicating the predetermined image formation range in the main scanning direction changes. The image processing method according to claim 6.   A program for realizing each means of the image processing apparatus according to any one of claims 1 to 6 by a computer.

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