JP2007043423A - Image processing method and apparatus thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively correct discoloration even in a general home to solve the problem that when an image printed out by a color printer is disposed to solar light, a fluorescent lamp or the like, the image may be discolored with the lapse of time. <P>SOLUTION: In the case of forming an image, information capable of discriminating discoloration related to image formation is multiplexed in the formed image as data, the information (information concerned with a printed matter, such as the information of the image used for printing, the information of a color printer, the information of a recording medium, and time information) multiplexed in image data read out from a scanner or the like is detected, the same information as the multiplexed information is calculated from the image data, a transformation function for the image is calculated by comparing the multiplexed information with the calculated information, and the transformation function is applied to the image data to restore the image discolored by changes over time to an undiscolored image image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus for correcting and restoring a faded image.

  In recent years, a digital camera (imaging device) that can take an image by a simple operation and convert it into digital image data, an image scanner that reads a document such as a photograph, and the like have been widely used. Images taken with such a camera and images read with an image scanner are stored in a PC (computer) or output to a color printer for printing at home.

  However, when an image printed by a color printer is exposed to sunlight or a fluorescent lamp, there is a problem that the color fades with time.

  In order to solve this problem, Patent Document 1 discloses a method of reading a faded image with an apparatus such as an image scanner and correcting the faded image to reproduce the original vivid image. According to this method, a photographic print with a pattern is obtained by exposing a pattern image of cyan, magenta, and yellow with predetermined saturation and lightness to a place outside the image recording area in addition to the image to be exposed. Create When this photographic print is faded due to changes over time, the color and density of each color component of cyan, magenta, and yellow are determined by comparing the color and density of the faded pattern with the color and density at the initial setting of each pattern. The correction amount is obtained, and a fading removal correction process (hereinafter abbreviated as fading correction) is performed on the image based on these correction amounts.

In Patent Document 2, a pattern image having a predetermined density in a predetermined area is recorded together with the subject image in the image area of the subject image on the recording medium, and the recorded pattern image is read together with the subject image. The image processing for obtaining the density information of the pattern image and the image data of the subject image and correcting the image data of the subject image based on the comparison between the density information of the read pattern image and the density of the predetermined pattern image is performed. Proposed.
JP-A-9-327945 JP 11-271946 A

  However, in the above-described method, a predetermined pattern is printed on a printed matter, and the correction amount is determined by comparing the pattern in the printed image with the color and density of the pattern before fading. Therefore, it is necessary to know information on the pattern in the printed image and information on the color and density of the pattern before fading.

  For this reason, in the developing laboratory that has performed printing, an appropriate correction amount can be obtained from the information on the pattern in the printed image and the information on the color and density of the pattern before the fading, so that the fading correction is performed satisfactorily. However, when information such as the color and density of the pattern before fading cannot be obtained, fading correction cannot be performed satisfactorily.

  In recent years, there are various types of color printers and recording media, so it is not possible to specify the type of color printer or the type of recording medium used to print the printed material from the printed material. Have difficulty. For this reason, it has been difficult to obtain information such as the color and density of the pattern before fading from the fading printed matter.

  The present invention has been made in view of the above-described conventional example, and an object thereof is to satisfactorily perform fading correction even in a general household.

  In order to achieve the above object, an image processing method of the present invention is an image processing method for correcting discoloration of an image formed on a recording medium, and is information capable of discriminating discoloration related to image formation at the time of image formation. Is multiplexed as data in the formed image, and when the color is corrected, the image is read to extract information added at the time of the formation, and the read image is corrected based on the information to be recorded on the recording medium. It is characterized by forming in.

  An image processing method for correcting discoloration of an image formed on a recording medium, wherein information capable of discriminating discoloration at the time of image formation is added as data to the image to form an image on the recording medium And a step of reading an image at the time of correcting the fading, a step of extracting information capable of discriminating the fading at the time of forming from the read image, and information capable of discriminating the fading at the time of forming from the read image. A step of generating corresponding information, a step of obtaining correction information based on information capable of discriminating a fading color at the time of formation and information generated from the read image, and an image read by the correction information And a step of forming on a recording medium by correcting the above.

  Here, the information capable of discriminating the fading color includes at least one of a density histogram of the formed image, a color reproduction range of the formed image, information on the recording apparatus and the recording medium, and information on the time of image formation.

  The image processing apparatus of the present invention is an image processing apparatus for printing an input image on a recording medium, and an information detection means for detecting information capable of discriminating a fading added to image data from the input image; Information calculation means for calculating information corresponding to the information capable of discriminating the added amber color from image data, and converting the input image data based on the added information and the information calculated from the image data And image conversion means for recording the image on a recording medium.

  Here, the image conversion means includes conversion function calculation means for calculating a conversion function for the input image from the added information and information calculated from the image data, and the conversion function is converted into the input image data. And an image is recorded on the recording medium by the converted image data. The information capable of distinguishing the multiplexed amber color is at least one of information on a printed image, information on a printing apparatus and a recording medium, and information on time. The information about the printed image is a histogram of each RGB channel. The information about the printed image is a thumbnail image. The information about the printed image includes at least the white point and black point chromaticity values of the image. The information regarding the printing apparatus and the recording medium is a chromaticity value of each ink on the recording medium.

  The image processing method of the present invention is an image processing method of an image processing apparatus for printing an input image on a recording medium, and detects information capable of discriminating a fading added to image data from the input image. And an information calculating step for calculating information corresponding to the information capable of discriminating the added fading color from image data, and the input based on the added information and the information calculated from the image data. An image conversion step of converting the image data and recording the image on a recording medium.

  According to another aspect of the present invention, there is provided an image processing apparatus for printing an input image on a recording medium, an adding unit for adding information capable of discriminating the image data from the input image, and the adding unit. Recording means for recording on the recording medium an image corresponding to the image data to which the information is added, and the information capable of discriminating the fading is obtained by using information calculated from the image recorded on the recording medium. It is information that can correct the fading of the image.

  The image processing method of the present invention is an image processing method of an image processing apparatus for printing an input image on a recording medium, and an additional step of adding information capable of discriminating the color of the image from the input image And a recording step for recording on the recording medium an image corresponding to the image data to which the information is added in the adding step, and the information capable of discriminating the fading is calculated from the image recorded on the recording medium It is information that can correct the fading of the image using information.

  Furthermore, a computer-executable program for realizing the image processing method and a storage medium for storing the program in a computer-readable form are also provided.

  As described above, according to the present invention, for example, information related to printed matter recorded on the printed matter together with the image, such as information on the image used for printing, information on the color printer, information on the recording medium, information on the printing time, etc. The information obtained from the time-varying printed material is obtained, and the information obtained from the time-varying image is compared with the various information recorded on the printed material, so that the time-changed image can be satisfactorily restored to the printed image. It becomes possible.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the present invention will be described by taking a multifunction printer as an example. However, the image processing method of the present invention is not limited to a specific apparatus, and a technical idea for correcting and restoring fading. And is applicable to various image reading apparatuses and image forming apparatuses, and these are also included in the present invention.

<Example of Configuration of Multifunction Printer Device of this Embodiment>
FIG. 1A and FIG. 1B are schematic perspective views of a multifunction printer apparatus (hereinafter, MFP apparatus) 1 according to an embodiment of the present invention. 1A is an external perspective view, and FIG. 1B is an external perspective view of the reading device 34.

  The MFP apparatus 1 has a function as a normal PC printer that receives data from a host computer (hereinafter referred to as a PC) and prints it, a function as a scanner, and a function that operates as a single MFP apparatus. A copy function for printing the read image with a printer, a function for directly reading and printing image data stored in a storage medium such as a memory card, or a function for receiving and printing image data from a digital camera .

  1A and 1B, the MFP apparatus 1 includes a reading device 34 such as a flat bed scanner, a printing device 33 such as an inkjet printer, and an operation panel 35 including a display panel 39 and various key switches. In addition, a USB port (not shown) for communicating with the PC is provided on the rear surface of the MFP apparatus 1 to perform communication with the PC. In addition to the above configuration, the MFP apparatus 1 includes a card slot 42 for reading data from various memory cards, a camera port 43 for data communication with a digital camera, and an auto for automatically setting a document on the platen. A document feeder (hereinafter referred to as ADF) 31 is also provided.

(Mechanical configuration example of MFP device)
FIG. 2A is a block diagram illustrating an example of a mechanism configuration of the multifunction printer apparatus according to the present embodiment.

  In FIG. 2A, the CPU 11 controls various functions provided in the MFP apparatus 1 and executes an image processing program stored in the ROM 16 in accordance with a predetermined operation of the operation unit 15. At this time, the RAM 17 is specified as a temporary storage for data and programs.

  The reading unit 14 having a CCD corresponds to the reading device 34 in FIG. 1B, reads a document image, and outputs analog luminance data of red (R), green (G), and blue (B) colors. Note that the reading unit 14 may include a contact image sensor (CIS) instead of the CCD. Further, if the ADF 31 as shown in FIG. 1A is provided, the order sheet can be read continuously, which is more convenient.

  The card interface 22 corresponds to the card slot 42 in FIG. 1A. For example, image data captured by a digital still camera (hereinafter referred to as DSC) and recorded on a memory card or the like is stored in a predetermined area of the operation unit 15. Read according to the operation. Note that the color space of the image data read via the card interface 22 is changed from a DSC color space (for example, YCbCr) to a standard RGB color space (for example, NTSC-RGB or sRGB) by the image processing unit 12 if necessary. ). Further, based on the header information, the read image data is subjected to various processes necessary for the application, for example, resolution conversion to an effective number of pixels as necessary.

  The camera interface 23 corresponds to the camera port 43 of FIG. 1A, and is used for reading image data by directly connecting to the DSC.

  The image processing unit 12 performs image processing such as image analysis, calculation of conversion characteristics, conversion from a luminance signal (RGB) to a density signal (CMYK), scaling, gamma conversion, error diffusion, and the like described later. The stored data is stored in the RAM 17. When the correction data stored in the RAM 17 reaches a predetermined amount necessary for recording by the recording unit 13 corresponding to the printing apparatus 33 of FIG. 1A, the recording operation by the recording unit 13 is executed.

  The nonvolatile RAM 18 is a battery-backed SRAM or the like and stores data unique to the MFP apparatus 1. The operation unit 15 corresponds to the operation panel 35 of FIG. 1A, selects image data stored in the storage medium, and starts a photo direct print start key, a key for printing an order sheet, and an order sheet. , A copy start key for monochrome copy or color copy, a mode key for specifying a mode such as copy resolution and image quality, a stop key for stopping copy operation, and a numeric keypad for inputting the number of copies It consists of a registration key. The CPU 11 detects the pressed state of these keys and controls each part according to the state.

  The display unit 19 corresponds to the display panel 39 of FIG. 1A and includes a dot matrix type liquid crystal display unit (LCD) and an LCD driver, and performs various displays based on the control of the CPU 11. Also, thumbnails of the image data recorded on the storage medium are displayed. The recording unit 13 corresponds to the printing apparatus 33 in FIG. 1A, and is configured by an inkjet type inkjet head, a general-purpose IC, and the like. Under the control of the CPU 11, the recording data stored in the RAM 17 is read and printed out as a hard copy.

  The drive unit 21 includes a stepping motor for driving the paper supply / discharge roller, a gear for transmitting the driving force of the stepping motor, and a driver circuit for controlling the stepping motor in each of the operations of the reading unit 14 and the recording unit 13 described above. Etc.

  The sensor unit 20 includes a recording paper width sensor, a recording paper presence sensor, a document width sensor, a document presence sensor, a recording medium detection sensor, and the like. The CPU 11 detects the state of the original and the recording paper based on information obtained from these sensors.

  The PC interface 24 is an interface between the PC and the MFP apparatus 1, and the MFP apparatus 1 performs operations such as printing and scanning from the PC via the PC interface 24.

(Memory storage configuration example)
FIG. 2B shows a storage configuration example of the memory of the MFP apparatus 1 of the present embodiment. FIG. 2B only shows data and programs related to the present invention, and other functions provided in the MFP apparatus 1 are omitted. In this example, the program is shown as being stored in the ROM 16 and various parameters are stored in the nonvolatile RAM 18. However, the present invention is not limited to this.

  The ROM 16 stores a fading correction program 16c in addition to the system program 16a of the MFP apparatus 1 and the image processing program 16b for realizing the functions of the MFP apparatus 1. Such a fading correction program 16c may be a program that realizes one fading correction method or a program that selects one from a plurality of fading correction methods.

  The nonvolatile RAM 18 uses parameters used for image processing of the MFP apparatus 1, for example, a color conversion parameter 18a for converting from RGB to YMCK, a gamma correction parameter 18b for gamma correction, and an error diffusion method. The parameter 18c and the like are stored, and the conversion characteristic parameter 18d in the present embodiment is stored. The conversion characteristic parameter 18d includes, for example, a mathematical expression or a table for obtaining a conversion characteristic value from a feature quantity created from image data and a feature quantity extracted from multiplexed data, or a block or orthogonal for obtaining a feature quantity from multiplexed data. Parameters used for conversion, classification, etc. are stored.

  Various data are temporarily stored in the RAM 17 when the CPU 11 executes the program in the ROM 16. For example, in the present embodiment, the fading correction mode flag 17a in the case of the program for selecting one of the above-described plural fading correction methods, the read image before the fading correction read from the scanner or input by the external device Data 17b, extracted feature value 17c added at the time of formation extracted from read image data 17b, generated feature value 17d generated from read image data 17b, extracted feature value 17c and generated feature value 17d, conversion characteristic parameters, etc. The read characteristic data 17b is converted using the conversion characteristic value 17e and the conversion characteristic value 17e, and the storage area of the image data 17f after the color correction is subjected to the color correction. When a fixed program is not stored in the ROM 16 but is loaded from an external storage unit such as a card or a network and executed, the program has a program load area 17g.

  The external storage unit 22 stores image data 22a read externally, a fading correction program 22b that is loaded into the RAM 17 and executed, and the like.

<Operation Example of Multifunction Printer Device of this Embodiment>
An outline of the operation of the MFP apparatus of the present embodiment based on the above configuration will be described below.

(Normal PC printer mode)
This is a print mode in which an image is printed based on print data sent from a PC (not shown). In this mode, when data from the PC is input via the PC interface 24, the data is sent to the recording unit 13 and printed by the printing device 33 based on the data from the PC.

(Scanner mode)
In this mode, data read by the reading device 34 is transmitted to a PC (not shown). In this mode, data read by the reading device 34 is transmitted to the PC via the reading unit 14 and the PC interface 24.

(Copy mode)
This is a mode in which image data read by the reading device 34 is processed in the MFP device and printed by the printing device 33. When a copy operation is instructed by the operation unit 15, the reading unit 14 reads a document placed on the document table. The read data is sent to the image processing unit 12 to perform processing such as background removal and black character processing, conversion from RGB signals to YMCK signals, gamma correction, error diffusion, and the like. Thereafter, the converted data is sent to the recording unit 13 for printing.

(Direct print mode from PC card)
When the PC card is inserted into or removed from the card slot 42, the MFP apparatus 1 can detect whether the PC card is inserted or removed (removed) via the card interface 22. When the PC card is inserted, image data (for example, JPEG data) stored in the PC card is read and stored in the RAM 17. Next, when printing of the selected image is instructed by the operation unit 15, the image processing unit 12 executes image data expansion, conversion from RGB signals to YMCK signals, gamma correction, error diffusion, and the like. The recorded data is sent to the recording unit 13 for printing.

(Direct print mode from camera)
When the DSC is connected to or disconnected from the camera port 43, the MFP apparatus 1 can detect whether the DSC is connected or disconnected via the camera interface 23. When the MFP apparatus 1 accepts a print instruction from the DSC after connecting the DSC, the MFP apparatus 1 reads the stored image data (for example, JPEG data) stored in the DSC and stores it in the RAM 17. Thereafter, the image processing unit 12 performs image data expansion, conversion from RGB signals to YMCK signals, gamma correction, error diffusion, and the like, and the converted data is sent to the recording unit 13 for printing.

<Procedure for fading correction>
A method for fading correction in a copying operation will be described with reference to FIG.

  In step S31 of FIG. 3, the document placed on the document table of the MFP apparatus 1 is read and stored in the RAM 17 (FIG. 4B). Next, in step S32, the multiplexed data from the data stored in the RAM 17 is detected by the image processing unit 12 (FIG. 2A), and the multiplexed image feature amount is analyzed. In step S33, a feature quantity similar to the multiplexed feature quantity is calculated from the image data stored in the RAM 17. If the multiplexed feature amount is a histogram for each of the RGB channels, a histogram for each of the RGB channels is calculated from the image data stored in the RAM 17 in step S33. As described above, in step S33, the feature amount related to the multiplexed data is calculated from the image data.

  In step S34, the feature amount detected in step S32 is compared with the feature amount calculated in step S33, and the conversion characteristics of the image stored in the RAM 17 are calculated. In step S35, the image data stored in the RAM 17 is converted by the conversion characteristics calculated in step S44. In step S36, conversion from RGB signals to YMCK signals, gamma correction, error diffusion, and the like are executed, and the converted data is converted. The data is sent to the recording unit 13 (FIG. 2A) and printed.

  FIG. 4 shows a method when the capacity of the RAM 17 is small.

  If the capacity of the RAM 17 is small, the entire image cannot be stored when the original is read at a resolution required for the copying operation. At that time, an image is read at a low resolution that can be stored in the RAM 17 at first and can detect multiplexed data, and conversion characteristics are calculated using the low resolution data. Thereafter, the read data is converted with the previously calculated conversion characteristics while reading the original with an appropriate resolution during the copying operation.

  FIG. 4 shows the above operation. In step S 41, the document placed on the document table of the MFP apparatus 1 is read at a low resolution and stored in the RAM 17. In step S42, the image processing unit 12 detects multiplexed data from the data stored in the RAM 17, and analyzes the multiplexed image feature amount. Next, in step S43, the same feature amount as the multiplexed feature amount is calculated from the image data stored in the RAM 17.

  In step S44, the feature quantity detected in step S42 is compared with the feature quantity calculated in step S43, and the conversion characteristics of the image stored in the RAM 17 are calculated. In step S45, the document placed on the document table of the MFP apparatus is read at a resolution suitable for copying. In step S46, the read image data is converted by the conversion characteristics calculated in step S54. In step S47, conversion from RGB signals to YMCK signals, gamma correction, error diffusion, and the like are executed, and the converted data is sent to the recording unit 13 for printing.

(Detection example of multiplexed information: S32, S42)
First, before describing detection of multiplexed information according to the present embodiment, creation of multiplexed information employed in the present embodiment will be described. Note that the multiplexed data creation / detection method applied in this example is an example of a multiplexed data creation / detection method already described in JP-A-2001-148778. The method is not limited to the above method.

  FIG. 5A describes an outline of creating multiplexed information in this embodiment.

  The original image information to be formed is subjected to pseudo gradation processing by the error diffusion method in the error diffusion processing unit 50. The original image information is simultaneously divided into predetermined areas (for example, rectangular areas) by the blocking processing unit 51. Then, it is sent to the quantization condition control unit 52. The quantization condition control unit 52 changes the quantization condition based on the additional information added to the image information. For example, a combination of quantization threshold values in the error diffusion method as three different quantization conditions corresponding to the bit value “0” and the bit value “1” of the additional information in the multiplexed region and outside the multiplexed region Are provided to the error diffusion processing unit 50 while selecting them to perform error diffusion processing of the original image information.

  FIG. 5B shows an example of a method for detecting multiplexed data in steps S32 and S42 from an image in which additional information is multiplexed by the method of FIG. 5A.

  In FIG. 5B, in step S51, four end portions that are assumed to be printed with image information in the printed matter are detected. If the printer resolution and the scanner resolution are the same resolution, the rotational direction (tilt) of the image should be corrected due to the skew during recording on the paper of the printer and the deviation when setting the printed matter on the scanner. It becomes a factor. Therefore, by detecting these four end portions, it is possible to determine how much the deviation occurs in the rotational direction. In step S52, the image area detected in step S51 is blocked in units of P × Q pixels. This block formation in P × Q pixel units is a block that is skipped at certain intervals, so that one block in P × Q pixel unit is included in an area assumed to be a block at the time of multiplexing. It is for blocking. In step S53, orthogonal transformation is performed on the blocked P × Q pixels. In step S54, class classification is performed, and class classification is performed for each band of orthogonal transform coefficients. In step S55, power comparison is performed, and the total power of each class is compared to determine a signal of additional information.

<Specific Example of Fading Correction 1: Correction Using Information of Image Used for Printing>
A fading correction method using a histogram of each color of RGB will be described with reference to FIGS. FIG. 6 is a flowchart showing a procedure for correcting the faded image data. This specific example is an example in which the feature amount of FIG. 3 is a histogram.

  In step S61 in FIG. 6, the document placed on the document table of the MFP1 apparatus is read. Next, in step S62, data embedded in the read image is detected. In step S63, a histogram is generated for each RGB component of the read image.

  FIG. 7 shows an example 61 of a histogram of Red components calculated from image data read by a scanner. FIG. 8 shows information detected from image data read by the scanner, and shows histogram information 62 of the Red component in the original image. Comparing the two histograms obtained from step S62 and step S63, the histogram 61 of the Red component calculated from the image data shown in FIG. 7 is different from the histogram 62 of the Red component in the original image shown in FIG. This indicates that the document placed on the document table faded with time. However, the shapes of the histogram 61 in FIG. 7 and the histogram 62 in FIG. 8 are similar. By matching the input values A to E in FIG. 7 with A ′ to E ′ in FIG. 8, the histogram 63 shown in FIG. It turns out that a shape close to the histogram 62 of FIG. 8 is shown.

  Step S64 in FIG. 6 is a step of calculating conversion characteristics for approximating the histogram obtained in step S63 to the histogram obtained in step S62. FIG. 10 shows conversion characteristics for converting the histogram 61 shown in FIG. 7 into the histogram 62 shown in FIG. 10, input values A to E represent input values A to E in FIG. 7, and output values A ′ to E ′ represent input values A ′ to E ′ in FIG. As shown in FIG. 10, the characteristic value of the histogram of the Red component calculated from the image data read by the scanner of FIG. 7 is matched with the characteristic value of the histogram of the Red component in the original image of FIG. Creates a conversion property that performs continuous conversion.

  In step S65 of FIG. 6, the conversion characteristic obtained in step S64 is performed on the value of the Red component read by the scanner. By this conversion, the red component histogram 61 of the amber image shown in FIG. 7 becomes the histogram 63 represented by the dotted line in FIG. 9, and the converted Red component histogram 63 represented by the dotted line is changed to the histogram 63 shown in FIG. 8 can be approximated to the Red component histogram 62 of the original image before fading shown in FIG.

  Similarly, regarding the Green component and the Blue component, by following the procedure of FIG. 6, each component can be brought close to the histogram before fading. By calculating and correcting the conversion characteristics of the read image data for each component of RGB, the faded image can be brought close to a vivid image before being faded.

<Specific Example of Fading Correction 2: Three-dimensional Correction Using Information of Image Used for Printing>
In the above-described specific example 1, the method of performing the fading correction by using the histogram of each color of RGB and correcting each component independently one-dimensionally has been described. However, the RGB component of each pixel is associated and the input image It is also possible to reproduce an image before fading more faithfully than the above example by performing a three-dimensional correction by using a thumbnail. This specific example is an example in which the feature amount of FIG. 3 is a color reproduction range (space).

  FIG. 12 shows a flowchart of a correction procedure using thumbnails.

  In step S121 in FIG. 12, the document placed on the document table of the MFP apparatus is read. Next, in step S122, data embedded in the read image is detected.

  Next, the color reproduction range of the image before fading is calculated from the thumbnail detected in step S123. FIG. 14 schematically shows a color reproduction range 72 of an image calculated using thumbnail information detected from image data read by a scanner. Next, the color reproduction range of the image is calculated from the image data read in step S124. FIG. 13 schematically shows the color reproduction range 71 of the image calculated from the image data read by the scanner. Comparing the two color reproduction ranges obtained from step S123 and step S124, the color reproduction range 71 calculated from the image data shown in FIG. 13 is different from the color reproduction range 72 in the original image shown in FIG. This indicates that the document placed on the document table faded with time.

  However, the shape of the color reproduction range is approximate, and in step S125 of FIG. 12, conversion characteristics for converting the color reproduction range 71 of FIG. 13 to the color reproduction range 72 of FIG. 14 are calculated. The conversion characteristics can be obtained by the rotation process from the solid line image 71 to the dotted line image 73 as shown in FIG. 15 and the enlargement process from the dotted line image 73 to the one-dot chain line image 74 as shown in FIG. .

  In step S126 of FIG. 12, the RGB values read by the scanner are converted using the conversion characteristics calculated in step S125. By this conversion, the color reproduction range 71 of the dark blue image shown in FIG. 13 can be brought close to the color reproduction range 72 of FIG. 14, so that the dark image can be faithfully brought close to the vivid image before the fade. .

  In the above embodiment, RGB signal histograms and thumbnail images are used as image information. However, histograms of signal values such as L * a * b * and YCbCr are used, and white points and black points in the reproduction range of each image are used. Further, it is also possible to use an 8-point color signal obtained by adding 6 points of red, green, blue, cyan, magenta, and yellow to the above-mentioned 2 points.

  In other words, in the present embodiment, the information about the original image obtained from the image that has changed with time is compared with the image information calculated from the image that has changed with time, so that the image that has changed with time can be restored to the original image. It becomes possible.

<Specific Example of Fading Correction 3: Correction Using Information of Color Printer and Recording Medium Used for Printing>
FIG. 17 shows a flowchart of a procedure for correcting the faded image data using the information of the color printer and recording medium used for printing. In this specific example, the feature amount of FIG. 3 is an example of information of a color printer and a recording medium.

  In step S171 of FIG. 17, the document placed on the document table of the MFP apparatus is read. Next, in step S172, dots of each color of ink used in the printer are extracted from the read image, and color information (L * a * b *) of each color is obtained.

  In step S173, data embedded in the read image is detected. The data embedded in the image is information of each ink color in the combination of the color printer used for printing and the recording medium. Specifically, the colorimetric values (L * a *) of each ink on the recording medium. b *) color information. By referring to this information, it is possible to know what color each color ink represented on the recording medium when it was recorded on the document, and how the color ink at the present time represents the color represented on the recording medium. A comparison can be made.

  In step S174, the lightness and saturation correction amounts are calculated from the color information extracted in steps S172 and S173. In step S175, the correction amounts calculated in step S174 are used to calculate all the values in the image read in step S172. Correction is performed on the pixel.

  In this embodiment, it has been shown that the fading correction is performed using dots of each color. However, since the recording medium itself also changes with time, it is more accurate by multiplexing the color information of the recording medium together with the ink color information. It is possible to perform a faint correction.

<Specific Example of Fading Correction 4: Correction Using Printed Time>
FIG. 18 shows the results of a light resistance test for each color of Cyan, Magenta, Yellow, and Black printed on photographic paper. In the graph of FIG. 18, the horizontal axis represents the conversion irradiation years, and the vertical axis represents the OD remaining rate. Reference numeral 181 represents the light resistance of Cyan approximated by a linear expression, reference numeral 182 represents Magenta, reference numeral 183 represents yellow, and reference numeral 184 represents the light resistance of each color of Black approximated by a linear expression.

  As shown in FIG. 18, there are variations in measured values, and not all data are arranged in an approximate straight line. That is, there is a variation in the data of each color obtained in step S172 in FIG. 17, and when there is a large variation in any of Cyan, Magenta, Yellow, and Black, the result of correcting the fading is not good. . Therefore, information on the printing time embedded in the image is acquired, and the correction amount for the ink color including a large error is recalculated by assuming the discoloration of each color ink over time, and good fading correction is performed. It becomes possible.

  In the above embodiment, the information related to the printed material is multiplexed in the image. However, a method such as using a barcode on the back surface or margin of the printed material is also possible.

  In the above-described embodiment, several examples are shown as the information of the feature amount stored in the image. However, the feature amount is not limited to these, and can be restored by correcting the discoloration due to the environment of the image or aging. Any information can be applied as long as it is a feature amount. The present invention is characterized in that this feature amount is embedded in an image as data, and is not limited to such a feature amount, and includes modifications thereof.

  In addition, the present invention may be applied to a system or an integrated device composed of a plurality of devices (for example, a host computer, an interface device, a printer, etc.) or an apparatus composed of a single device.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or apparatus, and to perform a computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. 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. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card 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.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

2 is an external perspective view of the outside of the MFP apparatus according to the present embodiment. FIG. 1 is a schematic perspective view of a reading device of an MFP apparatus according to an embodiment. 3 is a block diagram showing a functional configuration of a main part related to control of the MFP apparatus according to the present embodiment. FIG. It is a figure which shows the memory | storage structure example of the memory of this embodiment. It is a flowchart which shows the example of a procedure of the fading correction in copying operation. 10 is a flowchart illustrating a procedure example of fading correction in a copy operation when the memory capacity is small. It is a block diagram for demonstrating the creation example of multiplexed data. It is a flowchart which shows the example of a detection procedure of multiplexed data. It is a flowchart which shows the example of a procedure of the fading correction using a histogram. It is a figure showing the histogram computed from image data. It is a figure showing the histogram detected from multiplexed data. It is a figure showing the histogram computed from image data, and the histogram after conversion. It is a figure showing the conversion characteristic of the histogram computed from image data, and the histogram detected from multiplexed data. It is a figure showing the histogram detected from multiplexed data, and the histogram after conversion. It is a flowchart which shows the example of a procedure of the fading correction using a color reproduction range. FIG. 6 is a diagram schematically illustrating a color reproduction range calculated from image data. It is the figure which represented typically the color reproduction range detected from multiplexed data. FIG. 6 is a diagram schematically illustrating conversion (rotation) of a color reproduction range. FIG. 6 is a diagram schematically illustrating conversion (extension) of a color reproduction range. It is a flowchart which shows the example of a procedure of the fading correction using an ink color. It is a graph which shows the result of the light resistance test of each color printed on the photographic paper.

Claims (15)

An image processing method for correcting discoloration of an image formed on a recording medium,
At the time of image formation, information capable of discriminating discoloration related to image formation is multiplexed as data in the formed image,
An image processing method comprising: reading an image when extracting a fading color, extracting information added at the time of forming, correcting the read image based on the information, and forming the image on a recording medium. An image processing method for correcting discoloration of an image formed on a recording medium,
A step of forming an image on the recording medium by adding information capable of discriminating a fading color at the time of image formation as data to the image;
A process of reading the image at the time of correcting the dark blue;
Extracting information capable of discriminating the discoloration at the time of formation from the read image;
Generating information corresponding to information capable of discriminating a fading color at the time of formation from the read image;
Obtaining correction information based on information capable of discriminating the fading at the time of formation and information generated from the read image;
An image processing method comprising: correcting an image read by the correction information and forming the image on a recording medium.   The information capable of discriminating the fading color includes at least one of a density histogram of a formed image, a color reproduction range of the formed image, information on a recording apparatus and a recording medium, and information on the time of image formation. The image processing method according to claim 1 or 2. In an image processing apparatus that prints an input image on a recording medium,
Information detecting means for detecting information capable of discriminating the amber color added to the image data from the input image;
Information calculation means for calculating information corresponding to the information capable of discriminating the added amber color from image data, and converting the input image data based on the added information and the information calculated from the image data And an image conversion means for recording the image on a recording medium.   The image conversion means includes conversion function calculation means for calculating a conversion function for the input image from the added information and information calculated from the image data, and applies the conversion function to the input image data. 5. The image processing apparatus according to claim 4, wherein the image is recorded on a recording medium by the converted image data.   5. The image processing according to claim 4, wherein the information capable of discriminating the multiplexed dark blue is at least one of information on a printed image, information on a printing apparatus and a recording medium, and information on time. apparatus.   The image processing apparatus according to claim 6, wherein the information related to the printed image is a histogram of each of RGB channels.   The image processing apparatus according to claim 6, wherein the information about the printed image is a thumbnail image.   The image processing apparatus according to claim 6, wherein the information regarding the printed image includes at least a chromaticity value of a white point and a black point of the image.   The image processing apparatus according to claim 6, wherein the information about the printing apparatus and the recording medium is a chromaticity value of each ink on the recording medium. An image processing method of an image processing apparatus for printing an input image on a recording medium,
An information detection step of detecting information capable of discriminating the amber color added to the image data from the input image;
An information calculation step of calculating information corresponding to the information capable of discriminating the added amber color from image data;
An image processing method comprising: an image conversion step of converting the input image data based on the added information and information calculated from the image data and recording an image on a recording medium. In an image processing apparatus that prints an input image on a recording medium,
Adding means for adding information capable of discriminating the color of the image data from the input image;
Recording means for recording an image corresponding to the image data to which information is added by the adding means on a recording medium;
The information capable of discriminating the fading is information capable of correcting the fading of the image using information calculated from the image recorded on the recording medium. An image processing method of an image processing apparatus for printing an input image on a recording medium,
An additional step of adding information capable of discriminating amber color to the image data from the input image;
A recording step of recording an image corresponding to the image data to which information is added in the addition step on a recording medium,
The information capable of discriminating the fading is information capable of correcting the fading of the image using information calculated from the image recorded on the recording medium.   A computer-executable program for realizing the image processing method according to claim 11.   A storage medium for storing the program according to claim 14 in a computer-readable form.

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