JP2000137806A - Image processing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image processing device and method which can fast correct the image at the time of output by deciding a correction parameter for the image data stored in the device and adding previously the decided parameter into an image data file. SOLUTION: A correction tag addition part calculates a proper correction parameter before the print processing and previously adds the correction parameter into an image data file as the extension tag information with respect to the image data which are stored in a memory 21. At the time of printing, a gamma table generation part 23 generates and corrects a gamma table 24 based on the extension tag information to shorten its processing time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus and method, and more particularly to an image processing apparatus and method for correcting image data stored in the apparatus.

[0002]

2. Description of the Related Art Conventionally, an image read by a color device (digital camera or scanner) or the like that does not use a color management system (CMS) or the like has low contrast due to improper gamma adjustment or the like. The image quality was low, such as low color saturation. When such a low-quality image is printed as it is, there is a disadvantage that only a print output with significantly deteriorated image quality can be obtained.

[0003] In order to solve this problem, when printing an input low-quality image, image data already stored in a storage device or the like is accessed and analyzed to capture the image characteristics. By performing appropriate correction processing according to the characteristics, the image quality of the output image could be improved.

[0004]

However, in the above-described conventional correction method, a correction parameter must be determined based on the image characteristics obtained as a result of the image analysis, and correction must be performed based on the correction parameter. There is a problem that the processing speed required for output is significantly reduced. In particular, when the resolution of image data is increased and the data amount is increased, the processing speed is extremely reduced.

In order to prevent the processing speed from decreasing due to such an increase in the amount of data, a method of thinning out data can be considered. In such a method, even if high-speed processing becomes possible, the processing resolution is reduced. , The appropriate correction processing cannot be performed, and the image quality of the output image is degraded.

The present invention has been made in view of such a problem, and determines a correction parameter for image data held in an apparatus and adds the correction parameter to the image data file in advance. An object of the present invention is to provide an image processing apparatus and a method thereof that enable high-speed image correction processing at the time of output.

[0007]

As one means for achieving the above object, the image processing apparatus of the present invention has the following arrangement.

That is, holding means for holding image data in a predetermined file format, analysis means for analyzing the image data, calculation means for calculating a correction parameter of the image data based on the analysis result, Adding means for adding a correction parameter to the image data file.

For example, the adding means adds the correction parameter as extended tag information of a file.

[0010] The image processing apparatus may further include a correction unit configured to perform a correction process on the image data based on the tag information of the correction parameter added by the addition unit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram showing the configuration of an image processing apparatus according to this embodiment. In FIG. 1, reference numeral 10 denotes an image input unit, which is a color device (digital camera or scanner) that does not use a color management system (CMS) or the like. An image processing unit 11 performs various types of image processing including an image correction process, which is a feature of the present embodiment. Reference numeral 12 denotes an operation unit, such as an operation panel, for inputting a command by the operator and notifying the operator of the status of the image processing apparatus. Reference numeral 13 denotes an image display unit that displays image data, such as a CRT. Reference numeral 14 denotes a communication unit that transmits and receives image data, and performs image input processing equivalent to the image input unit 10 and image output processing equivalent to the image output unit 15 by being connected to an external host computer or the like. Can do it. An image output unit 15 prints out image data on a recording medium such as a printer.

FIG. 2 is a block diagram showing a functional configuration of the image processing section 11. As shown in FIG. In the figure, reference numeral 30 denotes a CPU, which executes a control program stored in a ROM 31 in advance to control operations of other components in the image processing unit 11 described later. A RAM 32 is used as a work area of the CPU 30.

The image data input from the image input unit 10 is first stored in a memory unit 21, and then a gamma value tag, which is a feature of the present embodiment, is added by a correction value tag adding unit 22. Hereinafter, the process of adding the gamma value tag will be described.

FIG. 3 is a flowchart of a gamma value tag adding process according to the present embodiment. First, step S10
In step 1, the user sets a target file to which a gamma value tag is to be added from the operation unit 12, and in step S102, executes a gamma value tag adding process if the processing execution conditions are satisfied.

Here, a method of setting a target file and setting an execution condition will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a diagram showing an example of a display screen of the operation unit 12 when setting a target file and setting an execution condition. FIG.
In the operation window W1, the tree structure of the file is displayed as shown in the figure, thereby enabling the user to search and set the target file. That is, since the entire view of the file system is expressed in a tree structure in the operation window W1, the user selects a desired file path with a mouse cursor or the like. The designated file path indicates that it has been selected by inverting the background color or the like. After setting the “Target file” and “Automatic execution schedule” items,
By pressing the “OK” button, a job scheduling command is issued. Note that, in any of the items, the process is appropriately performed without performing a troublesome setting process by specifying “default”.
It can be changed by "Detailed setting" or the like.

A plurality of files can be simultaneously specified as target files by specifying a file path or the like. In the setting of the target file, it is possible to combine file types, date processing, and others as condition items by using conditional expressions.
That is, in the “target file” item of FIG.
By pressing the button, the operation window W shown in FIG.
3 is displayed. By pressing the "file type", "date condition", and "others" buttons in the operation window W3, the operation windows W3 shown in FIGS. 5B, 5C, and 5D are respectively displayed.
4, W5, and W6 are displayed, and a flexible search and setting of a target file can be performed based on a condition desired by the user.

By pressing a “detailed setting” button in the “automatic execution schedule” item of FIG.
The operation window W7 shown in (e) is displayed. Thereby, “execution user (specifying file access authority)”, “priority” as a back process, “execution time designation”, and the like can be arbitrarily set. For example, the “execution time specification” is effective in that the execution of other jobs in the image processing apparatus of the present embodiment or a system including the apparatus is relatively small, and the automatic execution is specified during a time period such as at night. Operation can be expected. Also, the configuration may be such that automatic execution start, stop, and return are performed according to the load status of the entire system while monitoring the load status of the CPU 30 and the like.

Returning to FIG. 3, when the processing is started in step S102, it is first determined in step S103 whether or not to end the gamma value tag adding processing while comparing the search target path map with the current path.

If not, the process proceeds to step S104,
Access a file on the current path. Then, in step S105, the file is stored in step S1.
It is determined whether or not the file is the search target file set in 01, and if so, in step S106, the gamma value tag is searched by referring to the header information, tag data, etc. in the file. As a result, if a gamma value tag has been detected, that is, if a gamma value tag has already been attached to the file, the flow advances to step S107 to determine whether the tag can be overwritten. If overwriting is possible, the process proceeds to step S108; otherwise, the process returns to step S103.

On the other hand, if no gamma value tag is detected in step S106, that is, if no gamma value tag is attached to the file, the process proceeds to step S108.

In step S108, image data (RGB values) is read from the searched file, and in step S109, the gamma value G is calculated based on the image data.
Calculate v. Here, a method of calculating the gamma value Gv will be described.

First, brightness data L is obtained from the RGB values of the image data according to the following equation.

L = 0.29 × R + 0.59 × G + 0.12 × B Then, the average value Lavg of the brightness data L in all pixels
Is calculated, and data Lv obtained by normalizing this is calculated. Here, if the RGB data of the image is 24 bits,
Since Lavg can take a value of 0 to 255, Lv = Lavg /
255. Based on the value Lv obtained in this way, a correction gamma value Gv is obtained by performing the following calculation.

Gv = ln (0.5) / ln (Lv) (In () is a natural logarithmic function and Lv ≠ 0) Then, in step S110, the corrected gamma value G
Write v to the image file as a gamma value tag.

FIG. 6 shows how a gamma value tag is added in the present embodiment. In FIG. 6, 60
1 is original image data to which N tag data have already been added. 602 is the image data 60
This is image data in which the (N + 1) th tag data 603 is newly added to 1. Step S10 in FIG. 3 described above
The gamma correction value Gv obtained in step 9 is written in the (N + 1) th tag data 603.

As described above, in the present embodiment, the gamma correction value Gv is simply added to the image file as tag data, and therefore has no effect on the original image data or other information. Therefore, the image file to which the gamma value tag is added can be returned to the original file at any time if necessary.

As described above, the correction value tag adding section 22
In, an image data is analyzed for one image file to obtain an appropriate gamma correction value, and this is added or updated as new tag data. Then, the processing shown in steps S103 to S110 in FIG. 3 is repeated for all target image files below the search target path.

The series of processes shown in the flowchart of FIG. 3 is more preferably implemented as a back process job or a daemon program executed in an operating system capable of executing multi-processes.

By adding a gamma value tag to an image file as described above, it is possible to reduce the time required for correction processing when printing the image file. Hereinafter, the correction processing of the image file to which the gamma value tag is added will be described.

Here, the storage format of the image data in the memory unit 21 will be described with reference to FIG.

In FIG. 7, image data to which a gamma value tag has been added is stored in a file 71 format. The details of the file format of the file 71 correspond to 602 in FIG. 6 described above. "Magic number" in 602,
“Version information” and “directory offset” correspond to the header information of the file 71 shown in FIG. 7, and similarly, “tag 1” to “tag N” are standard tag sets, and “tag N + 1” is “gamma value tag”. Is equivalent to

In FIG. 7, reference numeral 70 conceptually shows various programs executed by the CPU 30. The image file 71 to which the gamma value tag is added is
It is converted into an internal format 72 of the application by an application program (hereinafter, application) executed by the PU 30. In general, an application that handles image data appropriately refers to necessary data in an image file, converts the data into an internal format, and continues processing. When performing printing processing to a printer, image data in an internal format of an application is transmitted to an OS using an API of an operating system (hereinafter, OS).
Is changed to conform to the internal format, and the image is transferred to the printer driver. That is, the image data in the application internal format 72 is converted into the OS internal format 73 and then into the internal format 74 in the printer driver.

As described above, in the present embodiment, it is necessary to pass the gamma value tag provided in the image file 71 to the printer driver, so that the application can pass the gamma value tag to the printer driver using a normal data structure. This is dealt with by adding an extended information area in addition to the body.

Returning to FIG. 2, the processing mainly by the printer driver will be described below. The printer driver performs gamma conversion based on the gamma value tag attached to the image file as described above.

First, the gamma table creation unit 23 creates a gamma table 24 based on the gamma value tag. In addition, from a plurality of gamma tables prepared in advance,
An optimal one may be selected and set in the gamma table 24. The gamma conversion unit 25 uses the gamma table 24 to output image data (RGB values) in the image file.
After performing gamma correction on the color space compression unit 2
Then, the image data is delivered to 6.

The color space compression section 26 performs a color space compression process based on the ICC color profile on the input gamma corrected RGB data, and then converts the RGB data into YMCK data by a color space conversion section 27. Next, the image data is binarized by the binarization processing unit 28 and then output to the image output unit 15 which is a printer engine unit.

As described above, according to the present embodiment,
Appropriate correction parameters are determined in advance for the image data stored in the file system and recorded in the extension tag of the file, so that appropriate image correction processing can be performed at high speed by referring to the tag information during printing. Can be performed.

<Second Embodiment> Hereinafter, a second embodiment according to the present invention will be described.
An embodiment will be described.

In the above-described first embodiment, an example has been described in which image data in a file is analyzed and an appropriate gamma correction value is set as a gamma value tag. In the second embodiment, gamma correction parameters are set. An example in which the setting can be arbitrarily set by the user is described.

FIG. 8A shows an example of a display screen on the operation unit 12 for making detailed settings for image correction (in this case, gamma correction) processing. In the figure, the description of the setting items common to FIG. 4 shown in the first embodiment will be omitted. That is, according to the operation window W8 shown in FIG. 8, in addition to the search and setting of the target file by the user and the setting of the automatic execution schedule, the detailed setting of the gamma correction for the image data of the target file can be performed.

When the "detailed setting" button is pressed in the "target processing" item, an operation window W9 shown in FIG. 8B is activated, and the user operates the reference window to obtain a reference average density value (TRD). , The correction width positive direction (AH), the correction width negative direction (AL), the correction strength (WGT), and other various parameters used for gamma correction can be checked and changed. Normally, for example, TRD = 98, AH = 1.2, AL = 0.8 are set as default values.

By setting these gamma correction parameters, a corrected gamma value is calculated by the following method.

For example, the average brightness of a print image is represented by Lv (Lv
≠ 0), the maximum density value is VMAX (VMAX ≠ 0), the upper limit AH and the lower limit AL of the correction gamma value are a function CfM, respectively.
() And the function CfS (), the correction gamma value Gv
Gv = CfS (CfM (ln (TRD / VMAX) / ln)
(Lv))) (where ln () is a natural logarithmic function).

By adding the correction gamma value Gv calculated in this way to the image file as extended tag information, flexible gamma correction can be performed. As described above, according to the second embodiment, the user can set a gamma correction parameter and the like, and can perform high-speed printing with an arbitrary image quality.

Third Embodiment Hereinafter, a third embodiment according to the present invention will be described.
An embodiment will be described.

In the first and second embodiments, the correction gamma value is attached to the file in advance as tag information, so that complicated processing such as image analysis at the time of printing is not required, and efficiency is improved. An example of realization has been shown. However, in some cases, printing may be desired without using a preset gamma correction value. So the third
In the embodiment, an example will be described in which a gamma correction tag attached to an image file can be treated as invalid.

FIG. 9 shows an example of a display screen on the operation unit 12 for setting color adjustment at the time of printing in the third embodiment. When “automatic setting” is selected in the operation window W11 shown in FIG. 9A, the image file to which the gamma correction tag is attached always develops the gamma table based on the corrected gamma value. After the image data is corrected, printing is performed.

On the other hand, if you do not want to use the gamma correction tag already attached to the image file,
The user selects “manual setting” in the operation window W11.
Here, when the “default” button on the operation window W11 is pressed, a preset setting value that is not related to the gamma correction tag is set. The operation window W12 shown in (b) is displayed. For example, if the user does not need gamma correction for printing, the user may select the item “unused gamma correction tag” in the operation window W12. The operation window W1
If you select the item "Use gamma correction tag" in 2,
That is, similar to the selection of “automatic setting” in the operation window W11,
Gamma correction based on the gamma correction tag attached to the image file is performed.

If a new gamma correction parameter is to be designated at the time of printing, the user selects the item “use setting during printing” in the operation window W12 and presses the “setting” button, whereby (c) in FIG. The operation window W13 shown in FIG. In this operation window W13, the user can arbitrarily set gamma correction parameters.

In this operation window W13, the user can arbitrarily set various parameters such as a reference average density value (TRD), a positive correction width direction (AH), a negative correction width direction (AL), and a correction intensity (WGT). Can be. By setting these various parameters, the correction gamma value can be calculated by the following method.

For example, the average brightness of a print image is set to Lv (Lv ≠
0), the reference average density value TRD (about 128 ± 30), and the maximum density value as VMAX (VMAX ≠ 0),
When the B data is 24 bits, the reference brightness Lt is:
It is represented by the following equation.

Lt = TRD / VMAX For example, in the setting example shown in the operation window W13, Lt = TRD / VMAX
98/255 = 0.3828.

Here, the upper limit AH of the correction gamma value is expressed by a function C
When fM () is defined and the lower limit AL is similarly defined by the function CfS (), the reference correction gamma value Gvx is Gvx = CfS (CfM (ln (Lt) / ln (Lv))) (where ln () Is a natural logarithmic function), the correction gamma value Gv is expressed by the following equation using the correction strength WGT: Gv = 1.0−WGT + Gvx × WGT.

As described above, since the correction gamma value Gv is calculated using the correction intensity WGT, even in a document in which a plurality of images are mixed, for example, the original average density of each image is kept as small as possible. In this case, it is possible to correct only a small amount.

For example, when printing is started by setting the reference average value TRD = 98 for a document in which a plurality of images A and B are mixed, the average density of the images A and B is 90 and 110, respectively. If the above calculation is executed, the gamma correction value applied to the image A is 5
If it is 0%, it becomes 0.959, and if the correction strength is 100%, it becomes 0.918. Similarly, the gamma correction value applied to the image B is 1.068 when the correction intensity is 50%, and 1.136 when the correction intensity is 100%. The closer the gamma correction value is to 1.0, the weaker the correction that does not impair the average density of the original image. Therefore, in the third embodiment, the gamma correction intensity, that is, the original image Can be set arbitrarily by the user.

As described above, the gamma correction value Gv obtained when the item “use setting during printing” is selected in the operation window W12 has priority over the tag information attached to the original image file. Is effective. Therefore,
For example, even if the gamma correction value = 1.2 has already been set in the image data A, the setting is ignored and a new gamma correction value calculated with the current setting is used.

Although the third embodiment has been described with respect to an example in which the use of the gamma correction tag is determined at the time of color adjustment, this is performed at any timing if convenience in use is considered. Alternatively, for example, the information previously set in the printing stage may be invalidated, and the user may set again on the spot.

As described above, according to the third embodiment, the correction parameters can be set by the user, and high-speed printing with an arbitrary image quality can be performed.

In addition to the image analysis method based on the average density value of all the pixels described in the first to third embodiments, there are more sophisticated and complicated gamma correction and color correction methods.

For example, the original image is divided into areas, and an average density value is obtained for each area, or an area such as a shadow portion, a highlight portion, or a medium density portion is detected, so that the entire image is not too dark. And a method of correcting the tone so as to be an optimal tone that is not too bright.

In any of the analysis methods, image data is appropriately analyzed, parameters for image correction are calculated, and the parameters are recorded in tag data or the like without deteriorating the originality of the image data. If the correction process is automatically executed appropriately based on the information such as the tag data,
The effect essentially equivalent to the present invention can be obtained.

In the present invention, the setting of the gamma correction parameter has been described as an example. However, the present invention is of course applicable to other image processing parameters.

The control program for performing the image analysis processing may be realized by a daemon program in the server, may be forked (executed) from an application program as needed, or simultaneously with the activation of the printer menu, or It may be executed simultaneously with the start of printing.

Also, an example in which image data is expanded in the memory 21 in the image processing unit 11 has been described. However, the present invention is not limited to this example. It is also possible to use a RAM, an external storage device, or the like.

[0067]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute 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 embodiment, 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 disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

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

[0073]

As described above, according to the present invention, a correction parameter is determined for the image data held in the apparatus, and the correction parameter is added to the image data file in advance, so that a high-speed output can be achieved. Enables image correction processing.

[0074]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a functional configuration of an image processing unit according to the embodiment.

FIG. 3 is a flowchart illustrating a gamma value tag adding process according to the embodiment.

FIG. 4 is a diagram showing an example of a setting screen according to the embodiment.

FIG. 5 is a diagram illustrating an example of a setting screen according to the embodiment.

FIG. 6 is a diagram illustrating details of an image data file format according to the present embodiment.

FIG. 7 is a diagram showing a storage format of an image data file in the embodiment.

FIG. 8 is a diagram showing an example of a setting screen for performing detailed setting of image correction parameters in a second embodiment according to the present invention.

FIG. 9 is a diagram illustrating an example of a setting screen for performing detailed setting of image correction parameters in a third embodiment according to the present invention.

[Explanation of symbols]

 Reference Signs List 21 memory 22 correction value tag adding unit 23 gamma table generation unit 24 gamma table 25 gamma conversion unit 26 color space compression unit 27 color conversion unit 28 binarization unit 30 CPU 31 ROM 32 RAM

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Claims (14)

[Claims] A storage unit configured to store image data in a predetermined file format; an analysis unit configured to analyze the image data; a calculation unit configured to calculate a correction parameter of the image data based on a result of the analysis; An adding means for adding a correction parameter to the image data file. 2. The image processing apparatus according to claim 1, wherein the adding unit adds the correction parameter as extended tag information of a file. 3. The image processing apparatus according to claim 2, further comprising a correction unit configured to perform a correction process on the image data based on the tag information of the correction parameter added by the addition unit. 4. The image processing apparatus according to claim 3, further comprising a printing unit configured to print out the image data corrected by the correcting unit, wherein the correction parameter is a parameter for printing the image data. Image processing device. 5. The image processing apparatus according to claim 4, wherein the correction parameter is a gamma correction parameter. 6. The image processing apparatus according to claim 1, further comprising setting means for setting the image data as a processing target. 7. The image processing apparatus according to claim 1, further comprising setting means for setting an execution schedule of said analyzing means, said calculating means, and said adding means. 8. The apparatus further comprises setting means for setting detailed parameters for determining a correction parameter, wherein the correction means calculates a correction parameter based on the detailed parameters set by the setting means, and The image processing apparatus according to claim 3, wherein the correction is performed based on the parameter. 9. The image processing apparatus according to claim 1, further comprising a selection unit configured to select which of a correction parameter added by the addition unit and a correction parameter based on the detailed parameter set by the setting unit is used. 9. The image processing apparatus according to claim 8, wherein the correction is performed based on the correction parameter selected by the selection unit. 10. The detailed parameter is an average density value,
9. The image processing apparatus according to claim 8, wherein the image processing apparatus includes one of a correction range and a correction intensity. 11. An input step of inputting image data held in a holding unit in a predetermined file format, an analyzing step of analyzing the image data, and calculating a correction parameter of the image data based on the analysis result. Calculation step, an addition step of adding the correction parameter to the image data file, and an output step of outputting the image data file to which the correction parameter is added to the holding unit and holding it again. Characteristic image processing method. 12. The image processing method according to claim 11, wherein in the adding step, the correction parameter is added as extended tag information of a file. 13. The image processing method according to claim 12, further comprising a correction step of performing a correction process on the image data based on the tag information of the correction parameter added in the adding step. 14. A recording medium on which a program code for image processing is recorded, the program code comprising: a code for an input step of inputting image data held in a holding means in a predetermined file format; A code of an analysis step of analyzing the image data, a code of a calculation step of calculating a correction parameter of the image data based on the analysis result, a code of an addition step of adding the correction parameter to a file of the image data, A code for an output step of outputting the image data file to which the correction parameter is added to the holding unit and holding the image data file again.