JPH10304393A - Image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method by which an image displayed on a monitor is converted easily into an image to be displayed on a television receiver. SOLUTION: Received digital RGB image data are converted into color space data in steps S1, S6, a gray axis of the color space data is corrected in a step S2, and a characteristic relating to the brightness of each image denoted by the color space data is extracted in a step S3. The brightness conversion is determined based on the characteristic relating to the extracted brightness in a step S4 and a hue of an image displayed on a television receiving is reserved in a step S7 and other color information than the brightness is converted and the color space data are inversely converted into digital RGB data in a step S5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing method for processing a color image displayed on a computer display such as a CRT or a monitor.

[0002]

2. Description of the Related Art In recent years, attention has been paid to device-independent color reproduction. For example, when an image is output from an application of a certain personal computer by an arbitrary printer, it is desired that the same color is output independently of the printer. This applies not only to printers but also to images displayed on personal computer monitors (hereinafter simply referred to as monitors). There is also a high demand that the color of an image displayed on a monitor be output as it is on a printer. In order to satisfy these requirements, the OS has also supported these processes. These are provided and realized in the form of profiles of devices such as a monitor, a printer, a scanner, and the like.
Various software have been released from each company as the profile creation tool.

[0003] In a digital still video camera (hereinafter referred to as DSVC), TV display is mainly used frequently. Also, with the rapid spread of personal computers, the number of monitor displays is increasing. However, color correction targets such as profiles are currently used for computer-related devices (monitors, monitors,
At present, it is limited to scanners and printers.

On the other hand, various measures have been taken to improve the visibility of a monitor in order to see characters in addition to images. As a main example, the luminance is suppressed as compared with a TV. In addition, a non-interlaced system that suppresses flicker is adopted as compared with the interlaced system of the TV to prevent flicker on the screen. Therefore, in order to reduce the difference between the color of the image displayed on the monitor and the color of the image displayed on the TV, it is first necessary to at least correct the luminance. This correction is also necessary because the TV displays an image with high saturation and an impact. Needless to say about color. As described above, the TV has a feature that the luminance and the saturation are higher than the monitor.

[0005]

However, when an image that has been clearly seen on a display screen of a TV is displayed on a monitor, an impression completely different from that of the image viewed on the TV due to a difference in processing is obtained. Further, if the image displayed on the monitor of the computer is printed out as it is, naturally, there is a difference between the luminous body and the reflective object, and there is a problem that a different impression is given.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an image processing method capable of easily converting an image displayed on a monitor into an image close to an image displayed on a TV.

[0007]

According to the first aspect of the present invention,
In an image processing method for processing an image displayed on a monitor so as to approximate an impression of an image displayed on a TV, a conversion step of converting input digital RGB image data into color space data; A correction step of correcting an axis, a feature extraction step of extracting a feature related to brightness of each image of the color space data, and a conversion determining a brightness conversion based on the feature related to brightness extracted in the feature extraction step. A determining step, a color information converting step of storing hue of the image displayed on the TV and converting color information other than the brightness of the color space data, and an inverse conversion of the color space data into digital RGB image data And an inverse conversion step.

Therefore, according to the present invention, by converting the input digital RGB image data into color space data, colorimetry can be performed by a colorimeter, and by correcting the gray axis of the color space data, the TV can be used. It is possible to match the color temperature of the monitor with the color temperature of the monitor, extract a feature related to brightness of each image of the color space data, and determine brightness conversion based on the extracted feature related to brightness.
It is possible to match the brightness between the TV and the monitor, save the hue of the image displayed on the TV, and convert the color information other than the brightness to obtain the hue of the image displayed on the TV. Can be maintained, and by converting the color space data that has gone through these steps back to digital RGB image data, for example, images captured from a film camera through a film camera, and images captured from a film via a film scanner, , An image displayed on a monitor, such as an image captured by DSVC or the like, can be easily converted to an image close to an image displayed on a TV.

According to a second aspect of the present invention, in the first aspect, it is determined whether or not to execute the image processing method before the conversion step of converting the input digital RGB image data into color space data. It is characterized by having an implementation decision step of making a decision.

Therefore, according to the present invention, the effect of the invention described in claim 1 is obtained, and it is set whether to convert an image displayed on the monitor into an image displayed on the TV. be able to.

According to a third aspect of the present invention, in the first or second aspect, a recording step of recording information as to whether or not the image processing method has been performed is provided.

Therefore, according to the present invention, the effect of the invention described in claim 1 or 2 can be obtained, and whether an image displayed on a monitor is converted to an image displayed on a TV or not. Can be easily confirmed, so that overlapping correction can be prevented.

According to a fourth aspect of the present invention, in the first aspect of the present invention, at least one of the TV and the monitor to be used as the monitor is selected, and the selection result is used as selection information. The method includes a selecting step of outputting and a simulator setting step of selecting and setting a corresponding simulator based on the selection information output in the selecting step.

Therefore, according to the present invention, the operation of the invention described in any one of claims 1 to 3 can be obtained, and at least one of the selected TV and the monitor is displayed on the monitor. It can be converted as an image displayed on a TV.

[0015]

Next, an embodiment of an image processing method according to the present invention will be described with reference to the drawings. FIG.
FIG. 3 shows a flowchart of the processing operation of the first embodiment of the image processing method according to the present invention.

As shown in FIG. 1, in the image processing method according to the first embodiment, a monitor simulator is first performed on input RGB image data (step S1), and the monitor Gray axis correction is performed on the data on which the simulator has been performed (step S2).

The input RGB image data is TV /
After the simulator is performed (step S6), the TV
A process of maintaining the color (color difference) data of the TV for the color (color difference) data among the data performed by the simulator (step S7).

In step S2, of the lightness (luminance) data among the data subjected to the gray axis correction, a characteristic amount is extracted (step S3), and the lightness (luminance) conversion is performed (step S4). -An inverse simulator is performed (step S5).

In step S2, of the data subjected to the gray axis correction, the color (color difference) data is processed to maintain the TV color (color difference) data (step S7).
After that, a monitor / inverse simulator is performed (step S
5).

The data after the monitor / inverse simulator is performed becomes corrected RGB image data, and the natural image is converted into digital RGB data and displayed on the monitor, so that the RGB image data has an impression close to TV. It is corrected so that

Next, each process in each step shown in FIG. 1 will be described. First, step S1
The monitor simulator and the TV simulator which are the processes in step S6 will be described.

The inside of these simulators may be any algorithm or conversion formula. Anyway, the simulator process is performed by passing the digital RGB image data through a processing system capable of converting the data into data of a certain color space. Examples of the color space include RGB, XYZ, CIELAB
(Hereinafter referred to as Lab), CIELUV, YUV, Munsell space, and many others. In the present embodiment, the following description is made using Lab as a color space to be used.

When the RGB displayed on the monitor is uniquely R
A monitor simulator provided with other color space data including GB is a monitor simulator, and a TV simulator on a TV. Arbitrary RGB is displayed on the TV and the monitor, and the color is measured with a colorimeter. Each simulator is created to reflect this result.

In other words, this processing means a tool for rejecting color space data having a value close to the actually measured value simply by inputting an arbitrary RGB to the simulator. As a matter of course, the difference between the monitor and the actual value measured by the colorimeter of the TV is 0
Is ideal, but actually includes a calculation error.
Here, each simulator is created based on the white of each device. As a result, the gray axis of each device described later is (L, a,
b) = A straight line passing through (0,0,0), (100,0,0).

By actually measuring the images displayed on the TV and the monitor in this way to create a simulator, it is possible to deal with a combination of an arbitrary TV and an arbitrary monitor.

Next, the gray axis correction in step S2 will be described. Since the TV and the monitor have variable color temperatures, the appearance of gray does not always match. TV
The typical value of the color temperature between the monitor and the monitor is 5000K,
There are 6500K and 9300K. These, 500
FIG. 2 shows an example in the case of 0K, 6500K, and 9300K.

As shown in FIG. 2, since the simulator is created on the basis of the white of each device, FIG.
2B and the 5000K monitor shown in FIG. 2B, the gray axis is (L, a, b) = black K (0, 0, 0), white W (100, 0, 0). ).

Here, as shown in FIG. 2C,
When calculating gray on the monitor side based on white of TV, TV
The maximum lightness L of the monitor with lower brightness L drops from 100 to L ′ (L ′ <100), and the chromaticity value (a, b) of white goes from (0, 0) to (a ′, b ′). Moving.

Then, as shown in FIG. 2D,
The gray axis is tilted so as to satisfy the following expression (1) in the direction of the moved white. Also, when there is a difference in black, it can be similarly corrected together with white, but it can be regarded as almost 0 on a black screen.

[0030]

(Equation 1)

Next, a description will be given of the feature extraction processing and the processing for maintaining the TV color (color difference) data shown in steps S3 and S7, respectively. Here, lightness (luminance) data and color (color difference) data used in each process are data calculated by each simulator, and lightness (luminance) data meaning a brightness component and a color (color) other than the data are calculated. Color difference) data. In Lab, L
Is brightness, and a and b are color data.

As described above, of the data divided into lightness (luminance) data and color (color difference) data, a feature amount extraction process is performed on the lightness (luminance) data, and the color (color difference) ) The data is processed to maintain the TV color (color difference) data.

The feature value extraction process in step S3 is a process of passing one image through a monitor simulator to obtain brightness data of one image. FIG. 3 shows a graph of frequency with respect to brightness data. As shown in FIG. 3, the white color of the monitor is (L, a, b) = (100, 0, 0) and the black color is (0, 0, 0).
0), the brightness frequency distribution of one image is 0 to
Take in a range of 100.

This distribution is divided into M sections, and the total frequency for each section, and the occupancy S
(%) Is obtained by the following equation (2). The example shown in FIG. 3 is divided into three parts, and the occupancy S is used as a feature amount.

[0035]

(Equation 2)

Next, the brightness (luminance) in step S4
The conversion will be described. FIG. 4 shows the relationship between the brightness conversion table 1 and the output L. As shown in FIG. 4, the feature amounts S ₀ and S ₁ obtained in step S3.
And S ₂ , the output lightness Lou with respect to the input lightness Lin
The table conversion is performed by selecting one of the many table data of t or creating one corresponding curve.

The input / output lightness conversion table 1 has T
The brightness data obtained by the V-simulator is compared with the brightness data obtained by the monitor simulator, and how the input / output brightness table on the monitor side is applied to the feature value to approach the TV impression in advance The association is performed in consideration of the above. As a result, a brightness conversion table is uniquely determined for the feature amount.

As a conversion table, it is general that the input brightness is an integer. Therefore, it is possible to obtain an output conversion brightness by performing linear interpolation or the like on a real number actually input. preferable.

Next, the processing for maintaining the TV color (color difference) data in step S7 will be described. When the color data a and b are given, the hue H and the saturation C of each of the TV and the monitor are obtained by the following equations (3) and (4). On the monitor side, the hue based on the color data of the TV is stored.

[0040]

(Equation 3)

Since the saturation C needs to be adjusted for expansion or compression, the color data is determined by the following equation (5) so as to maintain the value multiplied by the coefficient. Here, α, β and k are coefficients, and a ′ _mon and b ′ _mon are the color data of the monitor after processing.

[0042]

(Equation 4)

Next, the monitor / reverse simulator in step S5 will be described. In this monitor / inverse simulator, the input / output relationship of the monitor / simulator is reversed. Therefore, by this processing, a certain Lab is uniquely converted to digital RGB image data.

Therefore, by the image processing method according to the first embodiment, it is possible to convert an image displayed on the monitor into an impression close to an image displayed on the TV.

Hereinafter, the processing in the image processing method according to the first embodiment will be referred to as TV-> mon processing.

Next, a second embodiment of the image processing method according to the present invention will be described with reference to the drawings.

FIG. 5 is a flowchart showing the operation of the image processing method according to the second embodiment. As shown in FIG. 5, in the image processing method according to the second embodiment, in step S10, the TV->
It is confirmed whether or not to perform the mon process. If the process is to be performed (YES), the process proceeds to step S11 and the TV->
If mon processing is performed and processing is not performed (N
o), end the operation as it is.

As described above, in the image processing method according to the second embodiment, the TV-> mon process, which is the process according to the first embodiment, is executed by the DSVC main unit or the computer application (software, hardware). In the case where the device is mounted, whether or not the device executes the TV-> mon process, that is, the device can freely switch the TV-> mon process on and off.

Therefore, according to the image processing method of the second embodiment, the same effect as that of the first embodiment can be obtained, and the on / off switching of the TV-> mon process can be freely switched. Can be.

Next, a third embodiment of the image processing method according to the present invention will be described with reference to the drawings.

The image processing method according to the third embodiment includes, in addition to the processing steps of the image processing methods according to the first embodiment and the second embodiment, on / off of TV-> mon processing.
This is a processing method further including a step of storing information of off.

FIG. 6 is a flowchart showing the operation of the image processing method according to the third embodiment. First, in step S15, it is checked whether the TV-> mon process has been performed. If the execution has been performed (Yes), the flag indicating the execution is turned on in step S16,
If the execution has not been performed (No), the flag indicating the execution is set to off in step S18. Step S1
7, the flag information and the image are made to correspond one-to-one, so that the TV-> mon processing on, o
Manages and saves ff information.

As a saving method, the image is written in a header portion of the image or on / off information is written in an area for collectively managing the image, and is stored while maintaining a one-to-one relationship with the image. The stored information can be freely known by the user and the application.

Therefore, according to the image processing method according to the third embodiment, the same effects as those of the first or second embodiment can be obtained, and TV-> mo.
It is possible to easily confirm whether or not the data has been subjected to n processing.

Next, a fourth embodiment of the image processing method according to the present invention will be described. In the image processing method according to the fourth embodiment, since there are many TVs and monitors, a library of simulators created in advance by each TV and monitor is held. Storage location is DSVC
The main unit is provided on a recording medium for recording an image, and the computer application is provided together with software. Therefore, the T
In this method, V and the monitor are input to the device from DSVC or a computer application, the corresponding simulator is loaded, and the parameters are set in the simulator unit.

FIG. 7 shows a flowchart of the operation of the image processing method according to the fourth embodiment. First, in step S20, a TV and a monitor to be used are selected from the device. Next, in step S21, a corresponding simulator is selected or loaded. Then, step S2
In step 2, parameters are set in the corresponding simulator section of the TV-> mon process, and then the operation is terminated.

Therefore, according to the image processing method according to this embodiment, the same effects as those of the image processing method according to the above-described first, second, or third embodiment can be obtained. Any T in TV-> mon processing
V, monitor can be used.

[0058]

Therefore, according to the present invention, a video printer is commercialized on the basis of a TV, and an image to be printed out from a personal computer is based on a monitor. In some cases, the color may be different when the image is output from a personal computer. However, the monitor display can be adjusted to a certain TV, and the same impression as watching on a TV from the monitor on the personal computer can be obtained. An image processing method capable of obtaining an image can be provided.

In some cases, a user who is editing an image based on a monitor does not need to keep the TV in mind.
Conversely, the user may be worried about what the display will look like on a TV. To satisfy both cases, o
An image processing method capable of freely setting n and off can be provided.

Also, once the TV-> mon process is performed on the image, the image becomes different from the original image. However, when this image is stored and re-opened for editing, the image is previously stored in the TV-> mon. Since it is possible to clarify whether or not the mon processing has been performed, it is possible to provide an image processing method capable of avoiding a disadvantage that the processing is performed twice and does not match the TV.

Further, it is possible to provide an image processing method capable of performing TV-> mon processing on an arbitrary TV and an arbitrary monitor.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation of a first embodiment of an image processing method according to the present invention.

FIG. 2 is a conceptual diagram of a gray axis correction process in the operation of the flowchart shown in FIG. 1;

FIG. 3 is a graph showing a frequency distribution of brightness of one image in the feature amount extraction processing of the flowchart shown in FIG. 1;

FIG. 4 shows brightness (luminance) of the flowchart shown in FIG.
It is a figure showing table conversion in conversion operation.

FIG. 5 is a flowchart showing the operation of the second embodiment of the image processing method according to the present invention.

FIG. 6 is a flowchart showing an operation of the third embodiment of the image processing method according to the present invention.

FIG. 7 is a flowchart illustrating an operation of an image processing method according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Lightness conversion table

Claims (4)

[Claims] 1. An image processing method for processing an image displayed on a monitor so as to approximate an impression of an image displayed on a TV, comprising: a conversion step of converting input digital RGB image data into color space data; A correction step of correcting a gray axis of the color space data, a feature extraction step of extracting a feature related to brightness of each image of the color space data, and a brightness based on the features related to brightness extracted in the feature extraction step. A conversion determination step of determining conversion; a color information conversion step of storing hue of an image displayed on the TV and converting color information other than brightness of color space data; and a digital RGB image of the color space data. An inverse conversion step of performing an inverse conversion to data. 2. The method according to claim 1, further comprising, before the converting step of converting the input digital RGB image data into color space data, determining whether to execute the image processing method. Item 10. The image processing method according to Item 1. 3. The image processing method according to claim 1, further comprising a recording step of recording information as to whether or not the image processing method has been performed. 4. A selecting step of selecting at least one of the TV and the monitor to be used as the TV and the monitor, and outputting the selection result as selection information, based on the selection information output in the selecting step. 4. A simulator setting step for selecting and setting a simulator.
The image processing method according to any one of the above.