JP2002185793A - Image forming device, image data processing method and recording medium for recording image data processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device such as a digital printer that corrects luminance of image data so as to make the lightness (density) of a part of a major object such as a skin part of a person proper when the device prints out an image photographed by a digital camera or the like. SOLUTION: The image photographed by the digital camera or the like is displayed on a monitor screen by using data of the image to be corrected and using a mouse or the like identifies the skin part of the person being the major object and whether or not the photographed scene is a back light scene is set. Then pixel data included in a range selected among the image data are extracted. On the occurrence of the back light scene, a mean value of the luminance of the selected range is calculated by using the pixel data at a prescribed ratio (e.g. 2/3) from the lower luminance, and when the scene is not the back light scene, the mean value of the luminance of the selected range is calculated by using the pixel data at a prescribed ratio from the higher luminance, and the luminance correction amount is calculated so that the calculated mean value of the luminance becomes a prescribed proper luminance value. Using the obtained luminance correction value corrects the entire image data and employing the corrected image data forms the image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting digital image data obtained by a scanner or a digital camera so that a main subject has an appropriate density.

[0002]

2. Description of the Related Art As a method of correcting the density of color digital image data, a method of correcting a histogram of each color component of RGB so that the average of the colors (densities) of all image data for each color of RGB becomes gray (gray). It has been known. This method is based on Evans's theorem that "when shooting a general outdoor scenery, mixing all the colors recorded in the image will make it close to gray".

[0003]

However, in the conventional color digital image data density correction method, for example, an image of a person photographed without using a flash against a bright background or a flash against a dark background is used. When image data having a bias in density over the entire screen, such as an image of a person photographed, is subjected to the density correction by the above method, there is a problem that the person who is the main subject is not properly corrected due to the influence of the background. I was

Therefore, image data corresponding to the color of the face of a person who is the main subject is extracted from the color digital image data, and only the extracted image data is used to correct the main subject to have an appropriate density. There is also a way to do this. However, when a photograph is taken indoors of a wooden building, since the image contains many color portions similar to the skin color of a person, the person who is the main subject may not always be corrected to an appropriate density. Similarly, when the color of the hair is close to skin color such as brown. There is a possibility that the density is corrected including the hair part, and the density of the face part of the person is not properly corrected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an image forming apparatus, an image data processing method, and an image processing method capable of appropriately correcting the density of a main subject in an image. It is an object to provide a recording medium on which a data processing program is recorded.

[0006]

In order to achieve the above object, a first image forming apparatus according to the present invention provides an image reproducing apparatus for reproducing an image on a monitor screen using image data composed of a plurality of pixel data. Means, a range selecting means for selecting a specific range among the images reproduced on the monitor screen, and a backlight setting for setting a backlight condition when the image reproduced on the monitor screen is in backlight or near backlight. Means, when a backlight condition is set, a predetermined ratio of pixel data is extracted from a pixel having a lower luminance among the pixel data included in the selected range, and the pixel data is selected when the backlight condition is not set. Pixel data extraction means for extracting a predetermined percentage of pixel data from the higher luminance of the pixel data included in the range, and using the pixel data extracted by the pixel data extraction means, Average brightness calculating means for calculating an average value of the brightness of the range; and correction amount calculating means for calculating a correction amount for correcting the calculated average value of the brightness to a predetermined brightness value. Image data correcting means for correcting all pixel data using the corrected correction amount, and image forming means for forming an image using the corrected image data.

[0007] A second image forming apparatus according to the present invention comprises an image reproducing means for reproducing an image on a monitor screen using image data composed of a plurality of pixel data, and an image reproduced on the monitor screen being backlit. Or, backlight setting means for setting a backlight condition in a state close to backlight, color specifying means for specifying the color of the pixel from each pixel data included in the image data, and A first pixel data extracting unit that determines whether a predetermined color is included in the pixel data and extracts pixel data having a predetermined color; and a pixel included in the selected range when a backlight condition is set. A predetermined percentage of pixel data is extracted from data having a lower luminance, and a predetermined percentage of pixel data having a higher luminance is selected from pixel data included in a selected range when a backlight condition is not set. Extract And the second pixel data extracting means that, second
An average luminance calculating means for calculating an average value of the luminance using the pixel data extracted by the pixel data extracting means, and a correction amount for correcting the calculated average value of the luminance to a predetermined luminance value. A correction amount calculating unit that calculates by calculation, an image data correcting unit that corrects all pixel data using the obtained correction amount, and an image forming unit that forms an image using the corrected image data. Features.

In each of the above structures, it is preferable that the correction amount is a value obtained by multiplying a difference between the predetermined luminance value and the average luminance value by a predetermined coefficient.

Further, it is preferable that the predetermined color is a color relating to human skin.

According to a first image data processing method of the present invention, there is provided an image reproducing step of reproducing an image on a monitor screen using image data composed of a plurality of pixel data, and an image reproducing step of reproducing the image reproduced on the monitor screen. A range selection step of selecting a specific range, a backlight setting step of setting a backlight condition when the image reproduced on the monitor screen is in a state of backlight or close to backlight, and when a backlight condition is set, A predetermined percentage of pixel data is extracted from the pixel data having the lower luminance among the pixel data included in the selected range, and when the backlight condition is not set, the pixel data having the higher luminance is extracted from the pixel data included in the selected range. A pixel data extraction step of extracting a predetermined percentage of pixel data from the pixel data, and using the pixel data extracted by the pixel data extraction means, averaging the luminance of the selected range. An average brightness calculation step of calculating the calculated brightness, a correction amount calculation step of calculating a correction amount for correcting the average value of the obtained brightness to a predetermined brightness value, and a correction amount calculation step of using the obtained correction amount. An image data correcting step of correcting all pixel data and a corrected image data outputting step of outputting corrected image data are provided.

According to a second image data processing method of the present invention, an image reproducing step of reproducing an image on a monitor screen using image data composed of a plurality of pixel data; A backlight setting step of setting a backlight condition in a state of backlight or near backlight, a color identification step of identifying a color of the pixel from each pixel data included in the image data, and a color identification of each pixel. A first pixel data extraction step of determining whether or not a predetermined color is included therein, and extracting pixel data having a predetermined color; and, if a backlight condition is set, the pixel data is included in the selected range. A predetermined ratio of pixel data is extracted from the pixel data having the lower luminance, and when the backlight condition is not set, the pixel data included in the selected range is extracted from the pixel data having the higher luminance with the predetermined ratio. A second pixel data extracting step of extracting the combined pixel data, an average luminance calculating step of calculating an average value of the luminance using the pixel data extracted in the second pixel data extracting step, and an average value of the calculated luminance A correction amount calculation step of calculating a correction amount for correcting the pixel value to a predetermined luminance value set in advance, an image data correction step of correcting all pixel data using the obtained correction amount, and a corrected image Outputting a corrected image data for outputting data.

In each of the above methods, it is preferable that the correction amount is a value obtained by multiplying a difference between the predetermined luminance value and the average value of the luminance by a predetermined coefficient.

Further, it is preferable that the predetermined color is a color relating to human skin.

A recording medium on which the first image data processing program of the present invention is recorded is provided with an image reproducing process for reproducing an image on a monitor screen using image data composed of a plurality of pixel data, A range selection process for selecting a specific range from among the reproduced images, a backlight setting process for setting a backlight condition when the image reproduced on the monitor screen is in backlight or near backlight, and a backlight condition setting. When the backlight condition is not set, the pixel data included in the selected range is extracted from the pixel data included in the selected range in a predetermined ratio from the lower luminance. A pixel data extraction process of extracting a predetermined percentage of pixel data from a pixel having a higher luminance, and using the pixel data extracted by the pixel data extraction means to select a luminance of a selected range. Average brightness calculation processing for calculating the average value of the above, a correction amount calculation processing for calculating a correction amount for correcting the calculated average brightness value to a predetermined brightness value, and a calculated correction amount Are recorded so as to cause a computer to execute an image data correction process of correcting all pixel data by using a computer and a corrected image data output process of outputting corrected image data.

[0015] A recording medium on which the second image data processing program of the present invention is recorded includes an image reproducing process for reproducing an image on a monitor screen by using image data composed of a plurality of pixel data, A backlight setting process for setting a backlight condition when the reproduced image is in backlight or near backlight, and a color for specifying the color of the pixel from each pixel data included in the image data composed of a plurality of pixel data A specific process, a first pixel data extraction process of determining whether a predetermined color is included in the specified color of each pixel and extracting pixel data having a predetermined color, and setting of a backlight condition In this case, a predetermined percentage of the pixel data included in the selected range is extracted from the pixel data having the lower luminance, and if no backlight condition is set, the pixel data included in the selected range is extracted. A second pixel data extraction process for extracting a predetermined ratio of pixel data from the higher brightness of the pixel data, and an average brightness for obtaining an average value of the brightness using all the pixel data extracted in the second pixel data extraction process. Calculating means, a correction amount calculation process for calculating a correction amount for correcting the average value of the obtained luminance to a predetermined luminance value set in advance, and correcting all pixel data using the obtained correction amount This is recorded so that the computer executes the image data correction processing to be performed and the corrected image data output processing to output the corrected image data.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described using a digital printer as an example. FIG. 1 shows an external configuration of a digital printer (digital photographic processing apparatus) according to the present embodiment. The same applies to a second embodiment described later.

A digital printer prints an image taken by a digital camera directly on a piece of photographic paper,
The image formed on the silver halide film is once read by a scanner and printed on a piece of photographic paper. As shown in FIG. 1, a digital printer uses R (red), G (green), B (blue), or Y (red) to define a minute area on photographic paper corresponding to each pixel of an image sensor of a digital camera or a scanner.
An image forming unit 100 that forms an image by exposing to light of any of the three primary colors (yellow), M (magenta), and C (cyan), and developing the exposed photographic paper; An image data processing unit 200 performs predetermined processing on data and outputs the processed data to the image forming unit 100.

The image forming section 100 includes magazines 101 and 102 in which a plurality of types (for example, two types) of long photographic papers having different widths are wound and stored, and the magazines 101 and 102 are stored.
The photographic paper pulled out of the photographic paper is cut into a predetermined size, the exposing unit 103 exposing the image transmitted from the image data processing unit 200 on the cut photographic paper piece, and the exposed photographic paper piece is developed, bleached, fixed and stabilized. Development processing unit 104
And a drying section 105 for drying the developed photographic paper pieces, and a sorter section 106 for sorting the dried photographic paper pieces into, for example, a film unit. The image forming unit 10
Reference numeral 0 does not include a light source, a lens, a shutter, and the like for enlarging and exposing an image on a film on a piece of photographic paper in a conventional analog photographic processing apparatus.

The image data processing unit 200 reads image data recorded on a recording medium such as a memory card or a CD-R, or reads / records data after correction on the recording medium. Device 20
1, a scanner 202 for directly reading an image formed on a film or photographic paper, a display 203 for displaying the read image on a monitor, and setting of backlight conditions, predetermined image processing, instructions for print processing, and the like. A keyboard 204 for input and a control circuit (not shown) for performing predetermined processing on image data to be printed, converting the data into control data for controlling the exposure unit, and outputting the control data to the image forming unit 100. It is configured. Further, the image data may be directly transmitted / received to / from another device via a modem, a LAN board, a communication line, or the like.

Next, FIG. 2 shows a block configuration for explaining the functions of the digital printer according to the first embodiment.

The image data input unit 210 is constituted by, for example, an input / output interface, a CPU, a ROM, a RAM, etc., and takes in digital image data output from the data recording / reading device 201 or the scanner 202, and
Store and save it temporarily. Here, the digital image data is the R value from each pixel of an image sensor such as a digital camera or a scanner that has captured the image data.
An output signal (RGB data) relating to luminance for each of the color components (red), G (green) and B (blue) is serially arranged, and is serially input / output via an interface.

The image reproducing section 211 is provided on the display 20.
3. Reproduce a pre-scan image on the monitor screen of the display 203 using the input image data, which is constituted by a CPU, a ROM, a RAM, and the like.

The range selection unit 212 is composed of a mouse, a keyboard 204, a CPU, a ROM, a RAM, and the like. In the pre-scan image reproduced on the display 203, an operator or a user selects a main subject (for example, a face of a person). Part) is identified.

The backlight setting section 213 is composed of a mouse, a keyboard 204, a CPU, a ROM, a RAM, and the like. The operator or the user determines that the pre-scan image reproduced on the display 203 is in a backlight or near backlight state. In this case, the user operates the mouse or the keyboard 204 to input a predetermined signal corresponding to the backlight state.

The pixel data extraction unit 214 includes a CPU, RO
M, RAM, etc., first, pixel data included in the range specified by the range selection unit 212 is extracted from the image data (first pixel data extraction), and a predetermined process is performed on each of the extracted pixel data. Then, the luminance corresponding to each pixel is calculated, and a luminance histogram is created. Next, when the backlight is set by the backlight setting unit 213, pixel data corresponding to a predetermined ratio (for example, 2/3) to the number of extracted pixel data is further extracted from the pixel data having the lower luminance. (Extraction of second pixel data). If the backlight is not set by the backlight setting unit 213, pixel data corresponding to a predetermined ratio (2/3) of the number of extracted pixel data is further extracted from the pixel data having higher luminance (see FIG. 4). Second pixel data extraction).

The RGB data includes color and luminance (brightness).
The RGB data is subjected to arithmetic processing shown in the following (Equation 1), and is converted into YCC data (C2, YY, C1) representing luminance information and color difference information. YY represents luminance information, and C1 and C2 represent color difference information. By this conversion, only information relating to luminance can be extracted from the RGB data.

[0027]

(Equation 1)

The average luminance calculation unit 215 includes a CPU, an RO,
M, RAM, etc., using the pixel data extracted by the pixel data extraction unit 214 and its luminance information,
The average value of the luminance in the selected range is calculated.

The correction amount calculation unit 216 includes a CPU, a ROM,
Comparing the calculated average value of the luminance of the main subject portion with a predetermined luminance value corresponding to a preset proper luminance, the main subject portion is made to have proper luminance (appropriate density). In addition, a correction amount necessary for matching the average value of the luminance with a predetermined luminance value is calculated,
And memorize it.

The image data correction unit 217 includes a CPU, an RO,
M, RAM, etc., and luminance (RGB data) of image data for all pixels using the calculated correction amount
Is corrected.

The corrected image data output unit 218 has an input / output interface and a CP as in the image data input unit 210.
U, ROM, RAM, etc.
And outputs the corrected image data.

The image forming section 100 forms an image on photographic paper using the corrected image data. The above CP
U, ROM, and RAM may be the same as each other, or may be different depending on the configuration of each unit.

Next, flowcharts of image data processing in the first embodiment are shown in FIGS. First, when image data is read by the image data input unit (step S1), the image reproduction unit 211
0 from the RAM of the display 2
03 (step S)
3). In this state, the user or the operator determines whether or not luminance correction is necessary for the displayed pre-scanned image (step S5). When luminance correction is not required, the user or operator proceeds to step S1 using a mouse or a keyboard. Return and display the next prescan image.

On the other hand, when the luminance correction is necessary, the pre-scan image displayed on the display 203 is displayed using the mouse or keyboard of the range selection unit 212.
The main subject area is selected by the user or the operator in a range that is recognized as the main subject, for example, a face portion of a person (step S7).

When the main subject area is selected, the backlight setting unit 213 displays a predetermined message on, for example, the display 203, and asks the user or the operator whether the pre-scan image is in a backlight or a state close to the backlight. The result of input by the user or operator is stored (step S
9).

After the selection of the main subject area and the setting of the backlight, the pixel data extraction unit 214 reads out the image data included in the selected range from the RAM of the image data input unit 210 (step S11). According to 1), luminance information YY for each pixel is extracted (step S).
13). Further, a luminance histogram of each pixel included in the selected range is created (Step S15).

Next, the pixel data extraction unit 214 determines the result input in step S9 (step S17),
When the backlight condition is set (YE in step S17)
S) Extracting a predetermined ratio (2/3 of the pixel data extracted by extracting the first pixel data) of pixel data included in the selected range from the one with the lowest luminance (second pixel data extraction) (Step S19), when the backlight condition is not set, a predetermined ratio (2/3) of pixel data is extracted from the pixel having the higher luminance among the pixel data included in the selected range (Step S21). . When the pixel data is extracted, the average luminance calculation unit 215 calculates an average value of the luminance in the selected range using the extracted pixel data and the luminance information (step S23).

The correction amount calculating section 216 compares the calculated average value of the luminance with a predetermined luminance value corresponding to a preset appropriate luminance, and calculates a luminance correction amount (step S25). When the brightness correction amount is calculated, the brightness correction amount is stored in a RAM or the like of the image data input unit 210 together with, for example, a frame number of the film for specifying the image data (step S27).

When the luminance correction amount is stored, the image reproducing unit 21
1 determines whether or not a pre-scan image has been displayed on the display 203 for all image data stored in the RAM of the image data input unit 210 (step S29). Repeats steps S1 to S29.

When the pre-scan has been completed for all the image data (YES in step S29), the image data correction unit 217 sequentially reads out the image data and the luminance correction amount for the image data (step S31), and sets the luminance correction amount. Is used to correct each image data (step S3
3) The corrected image data is stored in a RAM or the like (step S35). Further, the image data correction unit 217
It is determined whether or not the luminance correction has been performed on all the image data to be subjected to the luminance correction (step S37).
If the correction has not been completed, steps S31 to S37
repeat.

When the correction of all the image data is completed, the corrected image data output section 218 determines whether or not to output the corrected image data to the image forming section 100 (Step S39). That is, when an image is formed using the corrected image data, the corrected image data output unit 218 outputs the corrected image data to the image forming unit 100 (Step S41). Then, the image forming unit 100 forms an image on the printing paper piece using the corrected image data output from the image data processing unit 200 (step S43), and ends this flow.

Next, the effect of correcting image data according to the first embodiment will be described with reference to FIG. An image captured by a digital camera or the like is shown in FIG.
As shown in (b), it is assumed that the scene is a “backlit scene” in which the luminance of the background is high (the density is low and bright) and the luminance of the main subject is low (the density is high and dark).

When an image is formed by using this image data without correction, an image of a backlight scene is obtained as shown in FIG. On the other hand, according to Evans's theorem, R
When the RGB color components are corrected so that the color of all the image data for each of the GBs becomes gray when the colors are averaged, FIG.
As shown in (c), the background is darkened so as to become gray, and the person who is the main subject having originally low luminance (high density and dark) is further darkened, and the details thereof are almost completely lost.

On the other hand, as in the present embodiment, the main subject portion is extracted, and the lower luminance (darker) pixel data included in the selected main subject portion is further extracted.
, A predetermined ratio (2/3) of the pixel data is re-extracted, and all the image data is corrected using the re-extracted pixel data and its luminance information so that the luminance (density) of the main subject portion becomes appropriate. 5, the influence of a part other than the main subject (for example, a wooden wall in the background) which is the same or similar to the color of the human skin can be reduced.
As shown in (a), the background having originally high luminance (low density and bright) is corrected to be even brighter, but the person who is the main subject is adjusted to the appropriate luminance (appropriate density) so that the details can be clearly identified. Will be corrected. As a result, appropriate correction can be performed even for an image having a bias in density such as a backlight scene.

Contrary to the example shown in FIG. 5, when the luminance of the main subject is high and the luminance of the background is low, such as when flash photography is performed in a dark place, that is, when the backlight condition is not set. Contrary to the backlight scene, a part other than the main subject (for example, a wooden wall in the background) having the same or similar color to the skin color of the person is the main subject part (for example, Since the luminance is lower than that of the person's face, a predetermined ratio (2/3) of pixel data is re-extracted from the higher luminance (brighter) of the pixel data included in the selected main subject portion. The entire image data may be corrected using the re-extracted pixel data and its luminance information so that the luminance (density) of the main subject portion becomes appropriate.

Second Embodiment Next, a second embodiment of the present invention will be described. In the first embodiment, the pre-scanned image is temporarily displayed on the display 203 using the input image data, and the user or the operator specifies the range of the main subject to be subjected to the luminance correction. In the second embodiment,
The color information of the image data is analyzed, and the part considered to be the main subject is automatically recognized using the color information.

FIG. 6 shows a block configuration for explaining the function of the digital printer of the second embodiment.

As in the case of the first embodiment, the image data input unit 220 includes, for example, an input / output interface, a CP
A digital image data output from the data recording / reading device 201 or the scanner 202 is fetched and temporarily stored and stored in the RAM or the like.

The image reproducing section 221 is connected to the display 20.
3. Reproduce a pre-scan image on the monitor screen of the display 203 using the input image data, which is constituted by a CPU, a ROM, a RAM, and the like.

The backlight setting section 222 is composed of a mouse, a keyboard 204, a CPU, a ROM, a RAM, and the like. An operator or a user determines that the pre-scan image reproduced on the display 203 is in a backlight or near backlight state. In this case, the user operates the mouse or the keyboard 204 to input a predetermined signal corresponding to the backlight state.

The color specifying section 223 includes a CPU, ROM, RA
M and the like, and performs predetermined processing on the input image data to specify a color of a portion corresponding to each pixel (hereinafter, simply referred to as “pixel color”). The above RGB
The data is information on color and luminance (brightness).
The arithmetic processing shown in the above (Equation 1) is performed on the GB data, and YCC data (C2, Y
Y, C1), it is possible to extract only the information on the color from the RGB data.

FIG. 7 shows color information two-dimensionally, with C1 as the vertical axis and C2 as the horizontal axis. The hatched area in FIG. 7 represents the average range of Japanese skin color when a person is photographed as a main subject.

The pixel data extraction unit 224 includes a CPU, an RO,
M, RAM, and the like.
It performs two functions of pixel data extraction and second pixel data extraction.

In the case of extracting the first pixel data, the color specifying unit 22
The color of each pixel specified by 3 is compared with a predetermined color representing a main subject set in advance, for example, a skin color of a person, and corresponds to the main subject and is included in a predetermined color or a predetermined range. All the image data corresponding to the pixels having the color are extracted and stored in a RAM or the like. Specifically, for all pixels, C calculated by the color specifying unit 223 is used.
The values of 1 and C2 are compared with the values of an LUT (look-up table) stored in a ROM or the like in advance, and
It is determined whether the values of 1 and C2 match the above-mentioned predetermined value or whether or not they are within a predetermined range. This allows
Pixel data relating to the main subject is extracted from all the pixel data.

In the case of the second pixel data extraction, predetermined processing is applied to the pixel data extracted by the first pixel data extraction processing, and the luminance corresponding to each pixel is calculated to create a luminance histogram. Next, when backlight is set by the backlight setting unit 222, pixel data corresponding to a predetermined ratio (for example, ２) to the number of extracted pixel data is further extracted from the pixel data having the lower luminance. (Extraction of second pixel data). If the backlight is not set by the backlight setting unit 222, pixel data corresponding to a predetermined ratio (2/3) of the number of extracted pixel data is further extracted from the pixel data having the higher luminance (see FIG. 4). Second pixel data extraction).

The average luminance calculation section 225 includes a CPU, an RO,
An average value of the luminance of a portion corresponding to the main subject is calculated using all the image data extracted by the second pixel data extraction processing. The present embodiment aims at correcting a main subject in an image to an appropriate luminance (density) without being affected by the luminance of other parts such as a background. Luminance information of only the part of the subject can be obtained.

The correction amount calculation unit 226 includes a CPU, a ROM,
Comparing the calculated average value of the luminance of the main subject portion with a predetermined luminance value corresponding to a preset proper luminance, the main subject portion is made to have proper luminance (appropriate density). In addition, a correction amount necessary for matching the average value of the luminance with a predetermined luminance value is calculated,
And memorize it.

The image data correction unit 227 includes a CPU, an RO,
M, RAM, etc., and luminance (RGB data) of image data for all pixels using the calculated correction amount
Is corrected.

The corrected image data output unit 228 has an input / output interface and a CP as in the image data input unit 220.
U, ROM, RAM, etc.
And outputs the corrected image data.

Next, flowcharts of image data processing in the second embodiment are shown in FIGS. As in the first embodiment, when image data is read by the image data input unit (step S51), the image reproduction unit 221
The image data is read from the RAM of the image data input unit 220, and a pre-scan image is displayed on the display 203 (step S53). In this state, the user or the operator determines whether or not luminance correction is necessary for the displayed pre-scanned image (step S55). If luminance correction is not required, the user or operator proceeds to step S51 using a mouse or a keyboard. Return and display the next prescan image.

On the other hand, when the luminance correction is necessary, the backlight setting section 222 displays a predetermined message on the display 203, for example, and asks the user or the operator whether the pre-scanned image is in the state of backlight or close to backlight. The result of input by the user or the operator is stored (step S5).
7). Next, the color specifying unit 223 displays a list of color charts and the like on a display, and provides a user or an operator with color information for specifying a main subject region using a mouse, a keyboard, or the like, for example, a person's skin color or the like. Is selected, and the selection result is set as color identification information (step S
59). Further, the color specifying unit 223 reads the image data from the RAM of the image data input unit 210, extracts the color information C1 and C2 for each pixel according to the above (Equation 1) (step S61), and for each pixel, Specify the color of the pixel.

When the color of the main subject area is specified, the pixel data extraction unit 224 compares the specified color of each pixel with the color of the main subject set in step S59 (step S63), and Only the pixel data of the pixel having the same color as the color or the luminance information YY is extracted and stored in the RAM or the like (first pixel data extraction: step S65).
Further, the pixel data extracting unit 224 determines whether or not the pixel color identification, comparison, and pixel data extraction have been completed for all pixels (step S67). S67 is repeated.

When the specification and comparison of the pixel colors and the extraction of the pixel data are completed for all the pixels, the average luminance calculation unit 2
25, a histogram of the luminance of all pixels having the same color as the color of the main subject is created using the pixel data or luminance information YY extracted in step S65 (step S6).
9).

Next, the pixel data extraction unit 224 determines the result input in step S57 (step S7).
1) When the backlight condition is set (YES in step S71), a predetermined ratio (2/3 of the pixel data extracted by the first pixel data extraction) from the lower luminance of the extracted pixel data. Pixel data is extracted (second pixel data extraction) (step S73), and when the backlight condition is not set, a predetermined ratio (2/3) of the pixel data included in the selected range from the one with the higher luminance is selected. ) Is extracted (step S75). When the pixel data is extracted, the average luminance calculation unit 225 calculates an average value of the luminance of the main subject area using the extracted pixel data and the luminance information (step S77).

The correction amount calculating section 226 compares the calculated average value of the luminance with a predetermined luminance value corresponding to a preset appropriate luminance, and calculates a luminance correction amount (step S79). When the luminance correction amount is calculated, the luminance correction amount is stored in a RAM or the like of the image data input unit 210 together with, for example, a frame number of the film for specifying the image data (step S81).

When the luminance correction amount is stored, for example, the correction amount calculating section 226 determines whether or not the luminance correction amount has been calculated for all the image data (step S83). If not completed, steps S57 to S83 are repeated.

When the brightness correction amount is calculated for all the image data (YES in step S83), the image data correction unit 227 sequentially reads out each image data and the brightness correction amount for the image data (step S85), Is used to correct each image data (step S8).
7) The corrected image data is stored in a RAM or the like (step S89). Further, the image data correction unit 227
It is determined whether or not the brightness correction has been performed for all the image data to be subjected to the brightness correction (step S91).
If the correction has not been completed, steps S51 to S91 are performed.
repeat.

When the correction of all the image data is completed, the corrected image data output section 228 determines whether or not to output the corrected image data to the image forming section 100 (Step S93). That is, when an image is formed using the corrected image data, the corrected image data output unit 228 outputs the corrected image data to the image forming unit 100 (Step S95). Then, the image forming unit 100 forms an image on the printing paper piece using the corrected image data output from the image data processing unit 200 (step S97), and ends this flow.

Other Embodiments In the above embodiments, the main subject region is specified, and the luminance correction amount is determined so that the average value of the luminance of the main subject region becomes a predetermined luminance value corresponding to the proper luminance. However, the present invention is not limited to this, and a predetermined coefficient (for example, 6
A value multiplied by an arbitrary value between 0 and 80%) may be used as the luminance correction amount. That is, as shown in FIG. 7, even if the main subject color is a person's skin color as an example, the main subject color may have a certain color range instead of a single color. If the luminance is corrected only for an area having (for example, the skin color of a person), the correction is excessive for the area of another color similar to that color, and the image quality after correction may be reduced. . Also, if the brightness of the main subject before correction is extremely high or low relative to the proper brightness, and the brightness of the main subject area is completely corrected to the proper brightness, the brightness of the parts other than the main subject will be abnormal. May be lower or higher. Therefore, in these cases, it is preferable that the luminance of the main subject region is not completely corrected to the proper luminance, but is corrected to a degree close to the proper luminance. Furthermore, in each of the above embodiments, the color of the main subject area is treated as a single color, but is not limited thereto, and may be a plurality of colors included in a predetermined range.

In each of the above embodiments, the image before correction is displayed as a pre-scan image on the monitor screen of the display 203. However, the image for printing is further displayed using the image data after correction. 20
3 may be displayed on the monitor screen. Furthermore, when displaying a pre-scan image on the monitor screen of the display 203 and when calculating the luminance correction amount of the main subject area, the number of pixels of the image data may be reduced and used.

Furthermore, in each of the above embodiments, a digital printer has been described as an example of an image forming apparatus. However, the present invention is not limited to this, and a personal computer and a color printer connected thereto, such as a thermal transfer type color printer, An inkjet color printer, a laser color printer, or the like may be used.

Further, the present invention is not limited to the image forming apparatus, but also includes a method for correcting image data executed by a personal computer and a recording medium on which a program for executing the method is recorded.

[0073]

As described above, according to the first image forming apparatus of the present invention, an image reproducing means for reproducing an image on a monitor screen using image data composed of a plurality of pixel data, Range selection means for selecting a specific range among the images reproduced on the monitor screen, and backlight setting means for setting a backlight condition when the image reproduced on the monitor screen is in a state of backlight or close to backlight, When the backlight condition is set, a predetermined ratio of pixel data is extracted from the lower luminance pixel data included in the selected range, and when the backlight condition is not set, the pixel data is extracted to the selected range. A pixel data extraction unit that extracts a predetermined percentage of pixel data from the pixel data having the highest luminance among the pixel data included, and a luminance in a selected range using the pixel data extracted by the pixel data extraction unit. Average brightness calculating means for calculating an average value, correction amount calculating means for calculating a correction amount for correcting the average value of the obtained brightness to a predetermined brightness value set in advance, and calculating the obtained correction amount. Image data correcting means for correcting all pixel data using the image data; and image forming means for forming an image using the corrected image data.

According to the first image data processing method of the present invention, an image reproducing step of reproducing an image on a monitor screen using image data composed of a plurality of pixel data, A range selection step of selecting a specific range from among the displayed images, a backlight setting step of setting a backlight condition when the image reproduced on the monitor screen is in backlight or close to backlight, and a backlight condition is set. When the backlight condition is not set, the pixel data included in the selected range is extracted from the pixel data included in the selected range. A pixel data extraction step of extracting a predetermined percentage of pixel data from a pixel having a higher luminance, and a selected area using the pixel data extracted by the pixel data extraction means. An average luminance calculating step of calculating an average luminance value, a correction amount calculating step of calculating a correction amount for correcting the calculated average luminance value to a predetermined luminance value, and a calculated correction amount An image data correction step of correcting all pixel data using the amount and a corrected image data output step of outputting corrected image data are provided.

Further, according to the recording medium on which the first image data processing program of the present invention is recorded, an image reproducing process for reproducing an image on a monitor screen using image data composed of a plurality of pixel data; A range selection process of selecting a specific range among images reproduced on the monitor screen, and a backlight setting process of setting a backlight condition when the image reproduced on the monitor screen is in a state of backlight or close to backlight, When the backlight condition is set, a predetermined ratio of pixel data is extracted from the lower luminance pixel data included in the selected range, and when the backlight condition is not set, the pixel data is extracted to the selected range. A pixel data extraction process of extracting a predetermined percentage of pixel data from the higher luminance among the included pixel data, and selecting the pixel data using the pixel data extracted by the pixel data extraction means. Average brightness calculation processing for calculating the average value of the brightness of the selected range, and correction amount calculation processing for calculating the correction amount for correcting the calculated average value of the brightness to a predetermined brightness value, An image data correction process for correcting all pixel data using the obtained correction amount and a corrected image data output process for outputting the corrected image data are recorded to be executed by a computer.

That is, according to these inventions, the user or the operator recognizes the main subject and uses the pixel data of the specified range on the monitor screen so that the brightness of the specified range becomes appropriate. Since the entire image data is corrected, it is possible to obtain an image in which the face portion of a person who is the main subject on the screen is corrected to an appropriate brightness (density) even in a backlight scene or flash photography, for example. it can. If the user or the operator determines that the scene is a backlight scene, a predetermined ratio (for example, 2/3) of pixel data from the darker one of the main subject areas is used. Since a predetermined ratio (for example, 2/3) of pixel data is used from the brightest one in the subject region, the background includes a region of the same or similar color as the color of the main subject (for example, the skin color of a person). Even in this case, the influence of the background portion can be reduced, and the density of the main subject can be corrected more appropriately. Further, since the range of the main subject of the image is specified by the user or the operator, the number of pixel data used for the luminance correction can be reduced, and the time required for calculating the luminance correction amount can be shortened.

According to the second image forming apparatus of the present invention, an image reproducing means for reproducing an image on a monitor screen using image data composed of a plurality of pixel data, and an image reproducing means for reproducing an image on the monitor screen. Backlight setting means for setting a backlight condition when the image is in backlight or near backlight, color specifying means for specifying the color of the pixel from each pixel data included in the image data, and each specified pixel A first pixel data extracting means for determining whether or not a predetermined color is included in the colors, and extracting pixel data having a predetermined color; and selecting a selected range when a backlight condition is set. A predetermined percentage of pixel data is extracted from the lower luminance one of the pixel data included in the pixel data, and when the backlight condition is not set, a predetermined percentage is selected from the higher luminance one of the pixel data included in the selected range. Percentage of pixels A second pixel data extracting means for extracting data, an average luminance calculating means for calculating an average value of the luminance using the pixel data extracted by the second pixel data extracting means, and an average luminance value calculated in advance. Correction amount calculating means for calculating a correction amount for correcting to a set predetermined brightness value, image data correcting means for correcting all pixel data using the obtained correction amount, and correcting the corrected image data. Image forming means for forming an image by using the image forming means.

According to the second image data processing method of the present invention, an image reproducing step of reproducing an image on a monitor screen using image data composed of a plurality of pixel data, A backlight setting step of setting a backlight condition when the image is in a state of backlight or close to backlight, a color identification step of identifying the color of the pixel from each pixel data included in the image data, Determine whether a predetermined color is included in the color of the pixel,
A first pixel data extraction step of extracting pixel data having a predetermined color, and, when a backlight condition is set, a predetermined ratio of pixel data having a lower luminance among pixel data included in the selected range. A second pixel data extraction step of extracting a predetermined percentage of pixel data from a pixel having higher luminance out of pixel data included in the selected range when the backlight condition is not set; An average brightness calculation step of calculating an average value of the brightness using the pixel data extracted in the extraction step, and a correction amount for correcting the calculated average value of the brightness to a predetermined brightness value by calculation. A correction amount calculation step to be obtained, an image data correction step to correct all pixel data using the obtained correction amount, and a corrected image to output the corrected image data Comprising an over data output step.

Further, according to the recording medium in which the second image data processing program of the present invention is recorded, an image reproducing process for reproducing an image on a monitor screen using image data composed of a plurality of pixel data; A backlight setting process for setting a backlight condition when an image reproduced on the monitor screen is in backlight or near backlight, and a color of the pixel from each pixel data included in the image data composed of a plurality of pixel data A first pixel data extraction process of determining whether a predetermined color is included in the specified color of each pixel and extracting pixel data having a predetermined color;
When a backlight condition is set, a predetermined ratio of pixel data is extracted from the lower luminance among the pixel data included in the selected range, and if the backlight condition is not set,
A second pixel data extraction process for extracting a predetermined ratio of pixel data from a pixel having a higher luminance among the pixel data included in the selected range, and using the all pixel data extracted in the second pixel data extraction process Average luminance calculating means for calculating an average luminance value, a correction amount calculating process for calculating a correction amount for correcting the obtained average luminance value to a predetermined luminance value, and a calculated correction amount Are recorded so as to cause a computer to execute an image data correction process of correcting all pixel data by using a computer and a corrected image data output process of outputting corrected image data.

That is, according to these inventions, the color of the main subject area input by the user or the operator, for example, the skin color area of a person is automatically detected and the brightness correction of the image data is performed. Although the number of pixel data used for calculating the luminance correction amount is larger than that in the first case, it is not necessary to select a main subject area for each image. For example, a plurality of image data are recorded on one recording medium. When printing all images,
It is possible to shorten the total processing time.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an external configuration of a digital printer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a block configuration of a digital printer according to the first embodiment of the present invention.

FIG. 3 is a flowchart of image data processing according to the first embodiment.

FIG. 4 is a continuation of the flowchart in FIG. 3;

FIG. 5 is a diagram for explaining an effect of luminance correction of image data according to the present invention.

FIG. 6 is a diagram illustrating a block configuration of a digital printer according to a second embodiment of the present invention.

FIG. 7 is a diagram showing color information two-dimensionally.

FIG. 8 is a flowchart of image data processing according to the second embodiment.

FIG. 9 is a continuation of the flowchart in FIG. 8;

FIG. 10 is a continuation of the flowcharts of FIGS. 7 and 8;

[Explanation of symbols]

 100: Image forming unit 200: Image data processing unit 210: Image data input unit 211: Image reproduction unit 212: Range selection unit 213: Backlight setting unit 214: Pixel data extraction unit 215: Average luminance calculation unit 216: Correction amount calculation unit 217: Image data correction unit 218: Corrected image data output unit 220: Image data input unit 221: Image reproduction unit 222: Backlight setting unit 223: Color specification unit 224: Pixel data extraction unit 225: Average luminance calculation unit 226: Correction amount Operation unit 227: Image data correction unit 228: Corrected image data output unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/46 H04N 1/40 101E 5C077 5/20 D 5C079 9/64 1/46 Z F term (Reference) 2H106 AA62 AA72 AA80 BH00 2H110 BA07 BA13 BA17 BA18 CE08 5B057 AA11 BA02 BA24 BA25 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC03 CE11 CE17 CE18 CH08 CH18 DA08 DA16 DA17 5C021 PA17 PA52 PA72 RB03 XA13 XA01 GBA GBA GAB KE01 KE09 KM11 5C077 LL04 LL19 MM20 MP08 PP15 PP32 PP34 PP37 PP46 PQ08 PQ19 PQ22 SS05 TT09 5C079 HB01 HB04 JA04 LA02 LA12 LA31 MA11 MA17 MA20 NA05 NA11 PA08

Claims (10)

[Claims] 1. An image reproducing means for reproducing an image on a monitor screen by using image data composed of a plurality of pixel data, and a range selecting means for selecting a specific range from the images reproduced on the monitor screen. And backlight setting means for setting a backlight condition when the image reproduced on the monitor screen is in backlight or near backlight, and when the backlight condition is set, the pixel data included in the selected range is A predetermined percentage of pixel data is extracted from the one with the lower luminance, and when the backlight condition is not set,
A pixel data extracting unit that extracts a predetermined percentage of pixel data from a pixel having higher luminance among the pixel data included in the selected range; and a selected range using the pixel data extracted by the pixel data extracting unit. Average brightness calculating means for calculating an average value of the brightness of the pixels, and correction amount calculating means for calculating a correction amount for correcting the calculated average value of the brightness to a predetermined brightness value. An image forming apparatus comprising: an image data correcting unit configured to correct all pixel data using a correction amount; and an image forming unit configured to form an image using the corrected image data. 2. An image reproducing means for reproducing an image on a monitor screen by using image data composed of a plurality of pixel data, and when the image reproduced on the monitor screen is in a state of backlight or near backlight. Backlight setting means for setting a backlight condition; color specifying means for specifying a color of the pixel from each pixel data included in the image data; and whether a predetermined color is included in the specified color of each pixel. First pixel data extracting means for judging whether or not the pixel data has a predetermined color, and a first pixel data extracting means for extracting pixel data having a predetermined color from a pixel having a lower luminance among pixel data included in the selected range when a backlight condition is set. The pixel data of the ratio of is extracted, and when the backlight condition is not set,
A second pixel data extracting means for extracting a predetermined ratio of pixel data from a pixel having a higher luminance among the pixel data included in the selected range, and using the pixel data extracted by the second pixel data extracting means, Average brightness calculating means for calculating an average value of the correction value; correction amount calculating means for calculating a correction amount for correcting the calculated average value of the brightness to a predetermined brightness value; and calculating the calculated correction amount. An image forming apparatus comprising: an image data correcting unit that corrects all pixel data using the image data; and an image forming unit that forms an image by using the corrected image data. 3. The image forming apparatus according to claim 1, wherein the correction amount is a value obtained by multiplying a difference between the predetermined luminance value and the average value of the luminance by a predetermined coefficient. 4. The image forming apparatus according to claim 1, wherein the predetermined color is a color related to human skin. 5. An image reproducing step of reproducing an image on a monitor screen using image data composed of a plurality of pixel data, and a range selecting step of selecting a specific range from the images reproduced on the monitor screen. A backlight setting step of setting a backlight condition when an image reproduced on the monitor screen is in backlight or close to backlight, and, when the backlight condition is set, the pixel data included in the selected range. A predetermined percentage of pixel data is extracted from the one with the lower luminance, and when the backlight condition is not set,
A pixel data extraction step of extracting a predetermined percentage of pixel data from the pixel data having the higher luminance among the pixel data included in the selected range; and a selected range using the pixel data extracted by the pixel data extraction means. An average brightness calculating step of calculating an average value of the brightness of the pixels; and a correction amount calculating step of calculating a correction amount for correcting the obtained average value of the brightness to a predetermined brightness value. An image data processing method, comprising: an image data correction step of correcting all pixel data using a correction amount; and a corrected image data output step of outputting corrected image data. 6. An image reproducing step of reproducing an image on a monitor screen by using image data composed of a plurality of pixel data, and in a case where the image reproduced on the monitor screen is in a state of backlight or near backlight. A backlight setting step for setting a backlight condition; a color specifying step for specifying a color of the pixel from each pixel data included in the image data; and whether a predetermined color is included in the specified color of each pixel. A first pixel data extraction step of judging whether or not the pixel data has a predetermined color, and, when a backlight condition is set, the predetermined pixel data included in the selected range from a pixel having a lower luminance in a predetermined range. The pixel data of the ratio of is extracted, and when the backlight condition is not set,
A second pixel data extraction step of extracting a predetermined percentage of pixel data from the pixel data included in the selected range in descending order of the luminance, and using the pixel data extracted in the second pixel data extraction step to extract the luminance of the pixel data. An average luminance calculating step of calculating an average value of the calculated luminance value; a correction amount calculating step of calculating a correction amount for correcting the average value of the obtained luminance to a predetermined luminance value set in advance; An image data processing method comprising: an image data correction step of correcting all pixel data by using the image data correction step; and a corrected image data output step of outputting corrected image data. 7. The image data processing method according to claim 5, wherein the correction amount is a value obtained by multiplying a difference between the predetermined luminance value and the average value of the luminance by a predetermined coefficient. . 8. The image data processing method according to claim 5, wherein the predetermined color is a color relating to human skin. 9. An image reproducing process for reproducing an image on a monitor screen using image data composed of a plurality of pixel data, and a range selecting process for selecting a specific range from the images reproduced on the monitor screen. And backlight setting processing for setting a backlight condition when an image reproduced on the monitor screen is in backlight or near backlight, and, when the backlight condition is set, the pixel data included in the selected range. A predetermined percentage of pixel data is extracted from the one with the lower luminance, and when the backlight condition is not set,
A pixel data extraction process for extracting a predetermined percentage of pixel data from the pixel with the highest luminance among the pixel data included in the selected range, and a selected range using the pixel data extracted by the pixel data extraction means. Average brightness calculation processing for calculating the average value of the brightness of the pixels, and correction amount calculation processing for calculating the correction amount for correcting the calculated average value of the brightness to a predetermined brightness value. Image data processing which is recorded so that a computer executes an image data correction process of correcting all pixel data using a correction amount and a corrected image data output process of outputting corrected image data. A recording medium on which a program is recorded. 10. An image playback process for playing back an image on a monitor screen using image data composed of a plurality of pixel data, and when the image played back on the monitor screen is in a backlight or near backlight state. Backlight setting processing for setting a backlight condition; color identification processing for identifying the color of the pixel from each pixel data included in the image data composed of a plurality of pixel data; A first pixel data extraction process of determining whether or not the pixel data includes the color of the pixel data, and extracting pixel data having a predetermined color; and a process of extracting pixel data included in the selected range when a backlight condition is set. A predetermined percentage of pixel data is extracted from the one with the lower luminance, and when the backlight condition is not set,
A second pixel data extraction process for extracting a predetermined percentage of pixel data from the higher luminance pixel data included in the selected range, and using all pixel data extracted in the second pixel data extraction process. Average luminance calculating means for calculating an average luminance value; a correction amount calculating process for calculating a correction amount for correcting the obtained average luminance value to a predetermined luminance value; and a calculated correction amount. An image data processing program characterized by being recorded so as to cause a computer to execute an image data correction process of correcting all pixel data by using a computer, and a corrected image data output process of outputting corrected image data. The recording medium on which it was recorded.