JP2003209855A - Image observing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image observing apparatus capable of properly reproducing colors by taking into account light source information during observation, light source information when photographing and light source information preferred by a user. <P>SOLUTION: An LCD panel 30 can select a reflection type (natural illumination type) or a transmission (backlight type) of a panel. When the panel of the reflection type observation system is selected, the panel acquires external light information such as a color temperature of external light from an external sensor 14 and reads information with respect to the light source when photographing and color reproduction attached to received image data as a display object to correct the color of the display image on the basis of the external light information and the information when photographing. Further, when a user designates desired light source information by using an information entry means 20, the panel corrects the color so as to obtain the image at the designated color temperature. When the transmission observing system is selected, since the effect of the external light is cancelled by the light emission of a backlight unit 34, no external light information is required and the color is corrected on the basis of the information when photographing and the designated color temperature information. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image observing apparatus, and more particularly to a color correcting technique suitable for a display unit or a printer of an information terminal device such as an electronic camera or a mobile phone.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 2001-103495 discloses white balance (WB) information at the time of photographing when a liquid crystal display device of an electronic camera uses a reflective liquid crystal and observes an image by reflection of external light. There is disclosed a technique for correcting the color characteristic of a display image in accordance with the color characteristic (color temperature) of external light based on.

In Japanese Patent Laid-Open No. 5-91376, light source information during liquid crystal observation is acquired by a WB sensor in a liquid crystal display device, and the color characteristic of a display image is set to the color temperature of external light based on the sensor information. A technique for driving the liquid crystal is also disclosed.

[0004]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In the method disclosed in Japanese Patent Laid-Open No. 001-103495, the atmosphere of the light source at the time of shooting is taken into consideration when the color temperature at the time of image capturing and the color temperature at the time of image viewing are different (that is, the location and time of the two are different) It has the drawback that it cannot be corrected.

On the other hand, the method disclosed in Japanese Unexamined Patent Publication No. 5-91376 does not use the light source information at the time of photographing for the display image, so that there is a drawback that it is not possible to make a correction in consideration of the atmosphere of the light source at the time of photographing. .

Further, as a drawback common to each of the above publications,
There is also a problem that it is not possible to cope with the case where the user tries to display an image under a desired color temperature.

The present invention has been made in view of the above circumstances, and image observation capable of appropriate color reproduction in consideration of light source information at the time of observation, light source information at the time of photographing, and light source information preferred by the user. The purpose is to provide a device.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 is an image observation apparatus capable of observing a target image by utilizing external light.
External light detecting means for acquiring external light information such as color temperature at the time of observation; additional information acquiring means for reading information related to the light source at the time of shooting and color reproduction added to the image data input as the display object; An image according to color correction means for performing color correction of the image data based on the external light information acquired by the external light detection means and the additional information acquired by the additional information acquisition means, and an image according to the image data color-corrected by the color correction means. And an image forming unit for outputting the content in an observable form.

The image observation apparatus includes a reflection type liquid crystal display, a printer and the like. The information on the light source and color reproduction at the time of shooting includes, for example, white balance information, light source type information, color temperature, reference white point, and assumed color space. According to the present invention, since the color characteristics of the output image are corrected by using the light source information at the time of observation and the light source information at the time of photographing (at the time of image recording), the atmosphere of the light source at the time of photographing in the observation environment can be controlled. Optimal color reproduction in consideration is possible.

According to a second aspect of the present invention, in the image observing apparatus having the above-mentioned structure, the image observing apparatus further comprises a light source designation input means by which a user can designate desired light source information, and the color correction means comprises the light source. The image data is color-corrected based on the light source information designated by the designation input means, the external light information, and the information acquired by the additional information acquisition means.

According to this aspect, the user can specify the desired light source information, and the image under the specified temperature can be displayed. For example, in a mail order, when a user thinks, "I want a swimsuit that looks beautiful in the sunlight," or "I want clothes that look beautiful under tungsten," the appearance under a specific light source can be changed. You can check.

According to a third aspect of the present invention, there is provided an image observing apparatus having an internal light source for generating light necessary for observing an image or an image observing apparatus in which a display unit itself emits light to display an image. Is an additional information acquisition unit that reads information about a light source and color reproduction at the time of shooting, which is added to the image data input as a display target, and a light source specification input unit that allows a user to specify desired light source information, Based on the additional information acquired by the additional information acquisition means and the light source information specified by the light source specification input means, a color correction means for performing color correction of the image data, and an image according to the image data color-corrected by the color correction means And an image forming unit for outputting the content in an observable form.

The present invention is directed to a so-called internal light-emission type image observation apparatus provided with an internal light source attached to the apparatus or a display section where the display section itself emits light. In the internal light emitting device, the influence of external light is canceled by the light emission of the internal light source or the display unit itself, and thus external light information is unnecessary. The internal light emission type image observation device includes a CRT, a transmissive liquid crystal display, a plasma display, an organic EL, and the like.

According to a fourth aspect of the present invention, in the image observation apparatus according to the first aspect, an internal light source for generating light necessary for image observation or the display unit itself emits light to perform image display. A switching unit that has a display unit and switches between an internal light emission type observation method capable of observing an image without using the external light and an external light type observation method for observing an image using the external light. , The correction processing function of the color correction means is automatically turned on in accordance with the switching of the observation method by the switching means.
It is characterized in that a correction control means for controlling ON / OFF is provided.

In the image observation apparatus in which the external light type observation method and the internal light emission type observation method are switched, when the external light type observation method is selected, the correction function utilizing the external light information is automatically enabled (ON). ) Is preferable. As this type of image observation apparatus, there is a transflective liquid crystal or the like.

According to a fifth aspect of the invention, in the image observation apparatus according to the second aspect, an internal light source for generating light necessary for image observation or the display unit itself emits light to display an image. A switching unit that has a display unit and switches between an internal light emission type observation method capable of observing an image without using the external light and an external light type observation method for observing an image using the external light. A correction control unit that automatically switches the correction processing function of the color correction unit in accordance with the switching of the observation method by the switching unit, and the correction control unit, when the internal light emission type observation method is selected, The color correction of the image data is performed based on the additional information acquired by the additional information acquisition means and the light source information specified by the light source specification input means, and when the external light type observation method is selected, the light source specification is performed. Input means Et given light source information, and wherein the controller controls the color correction unit means to perform color correction of the image data based on the additional information acquired by the outside light information and the additional information acquisition unit.

In an image observation apparatus in which the external light type observation method and the internal light emission type observation method are switched, the color correction function is automatically switched according to the observation method, and the color correction suitable for each method is realized. Is preferred.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an image observation apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a mobile phone to which an image observation apparatus according to an embodiment of the present invention is applied.

The mobile phone 10 includes a communication data input / output unit 12, an external sensor 14 for detecting the color temperature of external light, a telephone unit 16 necessary for functioning as a telephone, telephone communication information, speed dial and other information. An information management / analysis function unit 18 for performing management / analysis of information, an information input means 20 such as a numeric keypad, an image additional information analysis function unit 22 for analyzing additional information of input image data, and an image of the input image data. An image processing means 24 for performing processing and a system controller 26 are provided, and these blocks are connected by a bus 28. The mobile phone 10 also includes a liquid crystal display (LCD) panel 30 as a display device.
And the LCD drive circuit 32 and the backlight unit 3
It is equipped with 4.

The communication data input / output means 12 is an interface unit for exchanging data with an external device such as a digital camera or a personal computer (not shown). Various communication methods can be used regardless of whether they are wired or wireless, and a signal processing circuit corresponding to the applied communication method is installed.

Although the detailed structure of the telephone means 16 is not shown, the telephone means 16 includes an antenna, a transmission / reception signal modulation / demodulation circuit, a voice input section (speaker microphone), and a voice output section (earpiece speaker). Etc., and has a well-known configuration necessary for achieving the call function. The information input unit 20 is a unit for the user to input an instruction, and includes various operation units such as a number key, a function key, a cross key, and an operation dial.

The image file input through the communication data input / output means 12 has various additional information recorded as tag information in addition to the main image data. The additional information includes the shooting date and time of the main image, information on shooting conditions such as flash firing status, white balance information, and light source type information,
It includes various information about the main image, such as the number of recorded pixels and the compression rate.

The image additional information analysis function section 22 analyzes the additional information of the input image file to obtain necessary information such as white balance information and provides it to the image processing means 24 and the system controller 26. Image processing means 24
Is a digital signal processing means realized by a CPU, an LSI, or a combination thereof, and includes an image decompression unit 41, a YCrCb → RGB conversion unit 42, a color correction processing unit 43,
And a white balance control unit 44, and a non-volatile storage unit (hereinafter, referred to as a white balance adjustment coefficient ROM) 45 that stores information about the white balance adjustment coefficient. When the image processing unit is realized by the CPU, each functional unit such as the image expansion unit 41 is realized by a program.

The image decompression unit 41 decompresses the input compressed image data. The YCrCb → RGB conversion unit 42 converts the image data in the luminance / color difference signal (Y / Cr / Cb) format into R (red) G
Processing for converting to (green) B (blue) image data is performed. The color correction processing unit 43 performs processing for correcting the color characteristics of the display target image. The contents of the correction process will be described later. The white balance control unit 44 stores the white balance adjustment coefficient ROM 45 in the white balance adjustment coefficient ROM 45 based on the white balance information obtained from the attached information, the color temperature obtained from the external sensor 14, and the user-specified color temperature inputted from the information input means. The white balance adjustment processing is performed by referring to the data table of.

The image data processed by the image processing means 24 is sent to the LCD drive circuit 32, converted into display data, and then output to the LCD panel 30. The LCD panel 30 has a reflective type (lighting type) and a transmissive type (backlight type).
It is a display device capable of switching between and. Reflective /
The transparent controller may be automatically controlled by the system controller 26, or may be switched based on a user operation according to a predetermined operation procedure.

The system controller 26 is a control unit for controlling the overall operation of the mobile phone 10, and controls the operation of the LCD drive circuit 32, the lighting control of the backlight unit 34, and the data communication control using the communication data input / output means 12. , Call control by the telephone means 16, image processing control by the image processing means 24, and the like.

Next, the mobile phone 1 configured as described above.
The image display operation at 0 will be described. [Example 1 of color correction] <Color temperature of image capturing light source: 3000K, image assumed color space: sR
GB, external light color temperature: 7500K> color temperature at the time of shooting is 3000
K, it is assumed that the ambient color temperature of ambient light is 7500K when the image is currently reproduced and observed on the display device. When the image assumed color space is the sRGB standard, the reference white point is D65. That is, the image is created on the assumption that the image is observed on a monitor having a color temperature of 6500K. In this case, it is generally 3000 in an image pickup device (eg, digital camera).
The image is created in consideration of the colors observed with the K light source when viewed under the 6500K light source. In this example, the observation light source of the image is 7500K, which is different from the 6500K of the sRGB standard. Therefore, it is possible to estimate the color under 3000K from the image data and calculate the color that can be seen when the color is viewed under 7500K. is necessary.

FIG. 2 shows a processing block diagram for realizing the color correction. According to the figure, when image data is input to the mobile phone 10 of this example from a digital camera or the like (# 1), the YCrCb data is RG-processed after necessary processing such as expansion processing.
Processing for converting to B data is performed (# 2). The RGB data obtained by this conversion process is data (RGB ₆₅₀₀ ) that is assumed to be observed under a 6500K light source.

Next, the RGB data is converted into XY in the chromaticity coordinate system.
Convert to Z data (# 3). 6500K thus obtained
Chromaticity point (XYZ ₆₅₀₀ ) to 3000K chromaticity point (XY
Z ₃₀₀₀ ) (# 4). This conversion is for Von Kries
It is possible to calculate with the inverse characteristic of the matrix by the color adaptation prediction theory such as. Then, the chromaticity point (XYZ ₃₀₀₀ ) of 3000K is set to 75.
Convert to chromaticity point of 00K (XYZ ₇₅₀₀ ) (# 5). This conversion can also be calculated using a matrix based on the chromatic adaptation prediction theory such as Von Kries. Thus, the chromaticity point of 7500K (X
YZ ₇₅₀₀ ) is obtained and converted into RGB data (RGB ₇₅₀₀ ) of 7500K (# 6).

After that, the white balance is adjusted (#
7). In the chromatic adaptation conversion based on the chromatic adaptation prediction theory such as Von Kries, gray is maintained as gray, so the haute balance adjustment is performed in order to approximate the actual impression.

The coefficients required for adjustment are stored in the white balance adjustment coefficient ROM 45, and the adjustment processing is performed using the coefficient data stored in this ROM.
As shown in FIG. 3, the white balance adjustment coefficient ROM 45 stores R / R corresponding to the difference between the external light color temperature and the photographing color temperature.
G gain and B / G gain coefficients are stored. In the figure, the relationship between the white balance gain and the color temperature difference is shown by a graph, but in reality, a lookup table equivalent to this graph is prepared. The color temperature difference vs. the color temperature difference in the white lance gain table is preferably not the K (Kelvin) unit but the reciprocal color temperature (unit: mired) as shown in FIG.

In the case of this example, a photographing light source 3000 under the external light of 7500K
In order to give an atmosphere of K, the R / G gain is set higher than the B / G gain, and the image is reproduced in an atmosphere under a reddish light bulb.

As shown in FIG. 2, the data whose white balance has been adjusted is sent to the LCD drive circuit 32 (#
8) Then, it is output to the LCD panel 30 through necessary signal conversion. Thus, the image is displayed on the LCD panel 30.

In the above description, the color characteristics of the display image are corrected in consideration of the color temperature at the time of photographing and the color temperature at the time of observation, but in the second embodiment described below, the color temperature specified by the user is further corrected. A mode for correcting the color characteristics will be described in consideration of the above.

[Second Embodiment] <Image photographing light source color temperature: 3000 K, image assumed color space: sRG
B, outside light color temperature: 7500K, user specified color temperature: 5000K> In this example, the color under 3000K is estimated from the image data, and the color visible when viewed under 5000K is calculated. is necessary. FIG. 4 shows the processing block.

According to the figure, the image data to be displayed is
(YCrCb data) is converted to RGB data, and RGB data is converted.
Data (RGB₆₅₀₀) Is converted to XYZ data of chromaticity coordinate system
To do. Thus obtained chromaticity point of 6500K (XYZ₆₅₀₀)
The chromaticity point of 3000K (XYZ_{30 00}), And then 3000K
Chromaticity point (XYZ₃₀₀₀) Is a chromaticity point of 5000K (XY
Z_{50 00}).

Thus, a chromaticity point of 5000K (XYZ ₅₀₀₀ ) is obtained, and this is used as RGB data of 5000K (RGB ₅₀₀₀ ).
Convert to. After that, the white balance is adjusted, the adjusted data is sent to the LCD drive circuit, and the image is reproduced.

In this example, the white balance adjustment coefficient RO
From M45, the R / G gain and G / B gain coefficients according to the difference between the external light color temperature and the user-specified color temperature as shown in FIG. 5 are referred to and set.

In the above embodiment, the external sensor 14 is used to detect the external light color temperature at the time of observation. However, the present invention is not limited to this example, and a digital camera or a mobile phone with a camera function is used. In the case of an image display device with an imaging function such as a terminal, a CCD image sensor or CM
It is possible to detect the external light color temperature by using an image pickup means typified by an OS sensor or the like.

Further, the applicable range of the present invention is not limited to the liquid crystal display device, but can be applied to all image observation devices (including a printing device and a display device) such as a printer, a CRT, a plasma display and an organic EL display.

2 and 4, an example of observing a display image by utilizing external light has been described, but when a backlight is used as an internal light source, the influence of external light can be almost ignored (backlight. External light information is unnecessary in color correction. So in this case,
The system controller 26 of FIG. 1 automatically switches the color correction function of the image processing means 24 in association with the use or non-use of the backlight. That is, when the backlight is used, color correction is performed based on the attached information of the image and the user-specified information without considering the external light information.

Further, in the image observing apparatus which is switched between the external light type observation method represented by the transmissive liquid crystal and the internal light emission type observation method, the external light information is utilized when the external light type observation method is selected. The correction function is automatically turned on (enabled),
When the internal light emission type observation method is selected, it is also preferable that the correction function is automatically turned off (disabled).

In the above-mentioned embodiment, the image data is input through the communication data input / output means 12, but the means for inputting the image data is not limited to this, and the image data is read from a recording medium such as a magneto-optical disk. You may do it. In this case, means (media interface unit, etc.) for reading and writing the recording medium is provided.

[0045]

As described above, according to the image observing apparatus of the present invention, the color characteristic of the output image is corrected by using the external light information at the time of observing the image and the light source information at the time of photographing the image. Therefore, it is possible to perform optimum color reproduction in consideration of the atmosphere of the light source at the time of shooting according to the observation environment.

Further, according to the present invention, the user is provided with the light source designation input means for designating the desired light source information, and the color correction is performed so that the user can see under the designated light source. An image under the color temperature desired by the user can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile phone to which an image observation apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a processing block diagram showing an example of color correction processing.

FIG. 3 is a graph showing the relationship between the white balance gain and the color temperature difference between the external light color temperature and the color temperature at the time of shooting.

FIG. 4 is a processing block diagram showing another example of color correction processing.

FIG. 5 is a graph showing the relationship between the white balance gain and the color temperature difference between the external light color temperature and the user-specified color temperature.

[Explanation of symbols]

10 ... Mobile phone, 12 ... Communication data input / output means, 14
External sensor, 20 ... Information input means, 22 ... Image additional information analysis function section, 24 ... Image processing means, 26 ... System controller, 30 ... LCD panel, 32 ... LCD drive circuit, 34 ... Backlight unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 9/79 H04N 1/46 Z 5C079 F term (reference) 2H093 NC42 NC54 NC55 NC56 NC62 ND02 ND06 ND17 ND24 5C055 AA03 BA06 BA08 EA02 EA04 EA05 HA37 5C065 AA01 BB02 CC01 FF02 GG15 GG31 5C066 AA03 AA05 CA17 EA04 EA14 EE03 GA01 GA02 GA05 KA12 KE09 KM01 KM12 KM13 KM14 5C077 LL19 MP08 PP32 PP34 PP37 PP71 PQ12 SS01 TT09 5C079 HB01 HB04 HB05 HB11 JA25 LA23 LB01 MA11 NA03 PA03 PA05

Claims (5)

[Claims] 1. An image observation apparatus capable of observing a target image using external light, wherein the image observation apparatus includes external light detection means for acquiring external light information such as color temperature during observation, and a display target. Additional information acquisition means for reading the information regarding the light source and color reproduction at the time of shooting, which is added to the input image data, and external light information acquired by the external light detection means and additional information acquired by the additional information acquisition means. On the basis of the above, there is provided color correction means for performing color correction of the image data, and image forming means for outputting the image content in an observable form in accordance with the image data color-corrected by the color correction means. Image observation device. 2. A light source designation input unit that allows a user to designate desired light source information, and the color correction unit includes the light source information designated from the light source designation input unit, the outside light information, and the additional information. The image observation apparatus according to claim 1, wherein the image data is color-corrected based on the additional information acquired by the acquisition unit. 3. An image observation device having an internal light source for generating light necessary for image observation or an image observation device in which a display unit itself emits light to display an image, wherein the image observation device is input as a display target. Additional information acquisition means for reading information related to the light source and color reproduction at the time of shooting added to the image data, a light source specification input means for allowing the user to specify desired light source information, and acquisition by the additional information acquisition means A color correction unit that performs color correction of the image data based on the additional information and the light source information specified by the light source specification input unit; and a form in which the image content can be observed according to the image data color-corrected by the color correction unit. An image observation device comprising: an image forming unit for outputting. 4. The image observation apparatus according to claim 1, wherein the apparatus has an internal light source that generates light necessary for image observation, or a display unit that itself emits light to display an image. A switching means for switching between an internal light emission type observation method capable of observing an image without using the external light and an external light type observation method for observing the image using the external light; An image observation apparatus comprising a correction control unit for automatically controlling ON / OFF of a correction processing function of the color correction unit according to switching of an observation method. 5. The image observation apparatus according to claim 2, wherein the apparatus has an internal light source that generates light necessary for image observation, or a display unit that itself emits light to display an image. A switching means for switching between an internal light emission type observation method capable of observing an image without using the external light and an external light type observation method for observing the image using the external light; Correction control means for automatically switching the correction processing function by the color correction means in accordance with the switching of the observation method, wherein the correction control means, when the internal light emission type observation method is selected, the additional information acquisition means The color correction of the image data is carried out based on the additional information obtained in step 1 and the light source information designated by the light source designation input means, and when the outside light type observation method is selected, the light source designation input means designates. Light Information, the image observation apparatus and controls the color correction unit means to perform color correction of the image data based on the additional information acquired by the outside light information and the additional information acquisition unit.