JP2013042561A - Image processing apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus and a control method therefor that enable appropriate setting of image quality for a vivid scene without troubling a user.SOLUTION: A vivid scene with a small number of colors and a vivid scene with a large number of colors are detected as a photographing scene for a subject on the basis of saturation and the number of hues of a video signal obtained by photographing (S103, S105). Then, color correction processing corresponding to the detected photographing scene is performed on the video signal (S107, S109, S110).

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly, to an image quality correction technique for the imaging apparatus.

  In the signal processing of the image pickup apparatus, appropriate image quality correction differs for each scene to be shot. For this reason, a technique is known in which a user selects a scene mode to be used for shooting from a plurality of modes, switches settings of the imaging device according to the selected scene mode, and performs image quality correction suitable for each scene mode. .

JP 2007-267170 A

  However, it is troublesome for the user to switch to an appropriate scene mode according to the shooting scene. Also, it is difficult for beginners to determine an appropriate scene mode.

  As a conventional technique, there is a technique that includes a brightness detection unit and a saturation adjustment unit, and changes the saturation of image data in accordance with a perceptual change in saturation corresponding to the brightness information of the subject (Patent Document 1). However, this adjusts the saturation according to the brightness of the subject, and does not consider whether the subject itself is vivid or colorful with many colors. For this reason, since common correction is applied regardless of the color depth and color distribution of the subject, the correction is not optimal for a single-colored vivid subject or a colorful subject with many colors. For example, for a single-colored and vivid subject, the correction effect is small by simply increasing the saturation.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging apparatus and a control method thereof that can perform appropriate image quality settings for a colorful scene without bothering the user.

  According to one aspect of the present invention, a shooting scene of a subject having a color number less than a predetermined value and a vivid scene, and a color number exceeding a predetermined value, depending on the saturation and the number of hues of a video signal obtained by shooting. Provided is an imaging apparatus comprising detection means for detecting a large number of vivid scenes, and correction means for performing color correction processing on the video signal in accordance with a shooting scene detected by the detection means Is done.

  According to the present invention, it is possible to provide an imaging apparatus and a control method therefor that can perform appropriate image quality settings for a colorful scene without bothering the user.

1 is a schematic configuration diagram illustrating a configuration of an imaging apparatus according to an embodiment. 1 is a perspective view illustrating an overview of an imaging apparatus according to an embodiment. The figure explaining the correction process according to the image scene in embodiment. The flowchart which shows the vivid scene determination process in embodiment. The flowchart which shows the monochromatic vivid process in embodiment. The flowchart which shows the colorful vivid process in embodiment. FIG. 5A is a flowchart showing a monochrome bright scene detection process in the embodiment, and FIG. 5B is a flowchart showing a colorful bright scene detection process.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram illustrating a configuration of an imaging apparatus according to the present embodiment. Reference numeral 101 denotes a lens, and a diaphragm 102 is disposed behind the lens 101. The light passing through the lens 101 and the diaphragm 102 is imaged as a subject image on the image forming surface of the image sensor 105. In the image sensor 105, the formed subject image is converted from an optical signal to a video signal.

  The video signal obtained by the image sensor 105 is sent to the signal processing unit 112. The video signal is subjected to color correction processing by the color correction processing unit 108 in the signal processing unit 112 and is output to the display 116 or recorded on the magnetic tape 115, the DVD disk 117, or the memory card 118. The camera information detection unit 110 detects camera information such as luminance and color and sends the detected camera information to the camera microcomputer 111. Processing other than color correction processing in the signal processing unit 112 is not shown here.

  The camera microcomputer 111 performs scene detection of a monochromatic and vivid scene, a colorful scene with many colors, and other normal scenes from camera information such as luminance and color obtained from the camera information detection unit 110. Determine the shooting scene. Further, a color correction value is calculated based on the determined scene. Then, by setting the calculated color correction value in the color correction processing unit 108, color correction of the video is performed, and processing is performed so that the color reproducibility of the video becomes appropriate. The vivid scene determination process, the monochromatic vivid scene detection process, the colorful vivid scene detection process, the color correction process for the monochromatic vivid scene, and the color correction process for the colorful vivid scene will be described in detail later.

  Further, the camera microcomputer 111 performs control such as accumulation and reading of the image sensor 105 through the image sensor control unit 106. In addition, the lens control unit 103 performs control such as focusing and zooming of the lens 101. Further, using the luminance information of the subject obtained from the image data obtained from the image sensor 105, the aperture 102 is controlled through the aperture control unit 104, and the shutter speed is controlled through the image sensor control unit 106. Then, exposure control is performed. Further, the camera shake at the time of photographing of the user is corrected by driving the lens 101 through the lens control unit 103 or by controlling the signal processing unit 112.

  2, a recording medium such as a DVD disk, a magnetic tape, and a memory card is accommodated in the imaging apparatus main body 120 so that a video signal and a still image can be recorded and reproduced. Reference numeral 121 denotes a lens unit. Reference numeral 122 denotes a microphone, which is provided for recording sound during shooting. Reference numeral 123 denotes an electronic viewfinder (EVF), which is provided for aiming and checking a subject when taking a picture by looking into the camera. Reference numeral 124 denotes a moving image trigger switch. The moving image trigger switch 124 is, for example, a push button, and is a switch operated by the user to transmit the start and end of moving image shooting to the device. Reference numeral 125 denotes a still image trigger switch. The still image trigger switch 125 is a push button, for example, and is a switch operated by the user to transmit the start and end of still image shooting to the device.

  Reference numeral 126 denotes a mode dial, which includes, for example, a rotary switch. The mode dial 126 can select, for example, “playback” set to the playback mode, “camera” set to the camera mode, and “OFF” which is not one of them. Reference numeral 127 denotes a group of operation switches on which keys for inputting a white balance mode and other menu operations and playback system operations are arranged so that the user operates the main body. Reference numeral 128 denotes a liquid crystal panel attached to the side of the main body so as to be freely opened and closed. Like the EVF 123, the liquid crystal panel 128 is mainly used for confirming a subject image during camera shooting and for displaying a reproduced image during reproduction. The liquid crystal panel 128 can be rotated in the horizontal direction while being opened from the imaging apparatus main body 120. Reference numeral 129 denotes a speaker, which is provided for outputting sound when reproducing. A battery 130 is detachable from the imaging apparatus main body 120.

  Next, image processing corresponding to a shooting scene applied to image data, which is a characteristic part of the present invention, will be described. In the present embodiment, based on image data captured from the imaging system, it is determined whether or not the scene in which the image data was captured is a vivid scene, and image processing according to the determination result is performed on the image data. Process. At this time, paying attention to the fact that the vividness is different if the color distribution is different in a vivid scene, different scene determination processing is performed according to the color distribution of the obtained image data, and a monochromatic vivid scene, colorful Different correction processing is performed depending on the bright scene.

  FIGS. 3A and 3B are both images when a flower is photographed, but the color distribution is different. (A) shows a case where various colors of flowers are photographed, and there are many colors present in the image. On the other hand, (b) represents a case where a flower of a certain color is photographed, and the number of colors existing in the image is small. In such a case, in human perception, an image with a large number of colors in (a) is easier to feel vividly with the same saturation than an image with a small number of colors in (b), and appropriate correction processing is different. . Therefore, in this embodiment, it is classified whether the scene where the image data was shot corresponds to a bright scene of single color or colorful, and correction processing is performed according to the classification result. Hereinafter, a scene in which the number of colors in the image is larger than a predetermined value as shown in FIG. 3A is referred to as a “colorful vivid scene”, and a scene in which the number of colors in the image is smaller than a predetermined value as shown in FIG. This is called “monochromatic vivid scene”.

  The vivid scene determination processing by the camera microcomputer 111 will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing the vivid scene determination processing of the present embodiment. When the power is turned on, the camera microcomputer 111 starts vivid scene determination (S101). First, using camera information such as luminance and color obtained from the camera information detection unit 110, it is determined whether the scene is a single color with a small number of colors or a vivid scene (S103). If it is a single-color vivid scene, the color correction processing unit 108 performs color correction processing suitable for a single-color vivid scene with a small number of colors (S107). On the other hand, if it is not a monochromatic vivid scene, it is next determined whether the scene is colorful and colorful (S105). If it is determined that the scene is colorful and vivid, the color correction processing unit 108 performs color correction processing suitable for a colorful scene with many colors (S109). On the other hand, if it is not a colorful vivid scene in S105, the color correction processing unit 108 performs normal color correction processing (S110). Specific correction processing of the single color vivid processing and the colorful vivid processing will be described in detail later.

  Next, monochromatic vivid processing by the camera microcomputer 111 in the imaging apparatus of the present embodiment will be described with reference to the flowchart of FIG. As described above, when the camera microcomputer 111 determines in S103 that the scene is a monochrome bright scene, the camera microcomputer 111 starts a color correction process suitable for the monochrome bright scene (S107). First, the main hue is acquired from the color distribution of the image obtained from the image sensor 105 (S114). Here, a hue histogram is generated, and the hue with the highest frequency is set as the main hue. Subsequently, in the hue histogram, the degree of concentration on the acquired main hue is acquired (S116). Specifically, the ratio of the sum of the main hue and the frequency of hues equal to or higher than a predetermined threshold adjacent to the total frequency is calculated. Next, a correction value for expanding the hue range in the color correction process is calculated according to the degree of concentration in the main hue (S118). Here, the higher the degree of concentration of the hue histogram of the subject, the larger the correction value of the correction process for expanding the main limited hue range. Subsequently, the color correction processing unit 108 performs color correction processing for expanding the hue range based on the calculated correction value (S120). Specifically, the hue range is expanded so that the spread of the histogram is equal to or greater than a preset threshold value. In the color correction process for expanding the hue, only the specific hue including the main hue is subjected to matrix calculation and color gain correction, and the input signal included in the specific hue is expanded and output in the hue direction. To process. Alternatively, the look-up table used for color correction is changed, and an input signal included in a specific hue including the main hue is processed to be output in the hue direction. In addition, the present invention is not limited to these processes as long as a correction value for expanding the hue range in the color correction process is obtained according to the degree of concentration in the main hue.

  Next, colorful vivid processing by the camera microcomputer 111 in the imaging apparatus of the present embodiment will be described with reference to the flowchart of FIG. As described above, when the camera microcomputer 111 determines that the scene is a colorful vivid scene in S105, the camera microcomputer 111 starts color correction processing suitable for the colorful vivid scene (S109). First, the spread of the color distribution is acquired from the hue histogram (S124). Specifically, the number of hues in which a block having a saturation greater than a predetermined saturation threshold (Th7) exists is calculated. Subsequently, a saturation up correction value in the color correction process is calculated according to the spread of the acquired hue histogram (S126). That is, as the number of hues increases, the saturation up correction value increases. Subsequently, in the color correction processing unit 108, based on the calculated correction value, color correction processing for increasing the overall saturation is performed on the video signal obtained by shooting (S128).

  Next, the monochrome vivid scene detection process (S103) and the colorful vivid scene detection process (S105) by the camera microcomputer 111 in the imaging apparatus of the present embodiment will be described with reference to the flowchart of FIG. FIGS. 7A and 7B are flowcharts showing details of the single-color vivid scene detection process in S103 and the colorful vivid scene detection process in S105, respectively.

  When the power is turned on, the camera microcomputer 111 starts monochromatic bright scene detection (S103). First, it is determined whether the average saturation is greater than a preset threshold Th1 (S132). When the average saturation is equal to or less than the threshold value Th1, the process proceeds to a colorful vivid scene detection process in S105. On the other hand, when the average saturation is larger than the threshold Th1, it is determined whether or not a region (block) in which the saturation is larger than the preset threshold Th2 is wider than a predetermined area (a predetermined number of blocks) (S134). ). If the region where the saturation is greater than the threshold value Th2 is not wider than the predetermined area, the process proceeds to the colorful vivid scene detection process in S105.

  On the other hand, if the region where the saturation is greater than the threshold value Th2 is wider than the predetermined area, it is determined whether the number of hues whose saturation is greater than the preset threshold value Th3 is in the range of Cmin to Cmax ( S136). If the number of hues whose saturation is greater than the threshold value Th3 is not in the range of Cmin to Cmax, the process proceeds to the colorful vivid scene detection process in S105. On the other hand, if the number of hues whose saturation is greater than the threshold value Th3 is within the range from Cmin to Cmax, it is determined whether the ratio of the peak hue region to the whole is greater than a preset threshold value Th4 (S138). . When the ratio of the peak hue area to the whole is equal to or less than the threshold Th4, the process proceeds to the colorful vivid scene detection process in S105. On the other hand, if the ratio of the peak hue region to the whole is larger than the threshold Th4, the scene determination is a monochromatic vivid scene, and the process proceeds to the monochromatic vivid process of S107.

  If no monochromatic vivid scene is detected, the process proceeds to a colorful vivid scene detection process in S105. First, it is determined whether the average saturation is greater than a preset threshold Th5 (S142). When the average saturation is equal to or less than the threshold Th5, the scene determination is a normal scene, and the process proceeds to the normal process of S110. On the other hand, when the average saturation is larger than the threshold Th5, it is determined whether or not the region where the saturation is larger than the preset threshold Th6 is wider than a predetermined area (S144).

  If the region where the saturation is greater than the threshold Th6 is not wider than the predetermined area, the scene determination is a normal scene, and the process proceeds to the normal processing of S110. On the other hand, if the region where the saturation is greater than the threshold Th6 is wider than the predetermined area, it is determined whether or not the number of hues whose saturation is greater than the preset threshold Th7 is greater than C (S146). When the number of hues whose saturation is greater than the threshold Th7 is C or less, the scene determination is a normal scene, and the process proceeds to the normal process of S110.

  If the number of hues whose saturation is greater than the threshold Th7 is greater than C, it is determined whether the ratio of the peak hue region to the whole is less than a preset threshold Th8 (S148). When the ratio to the entire peak hue region is equal to or greater than the threshold Th8, the scene determination is a normal scene, and the process proceeds to the normal processing of S110. On the other hand, when the ratio of the peak hue area to the whole is smaller than the threshold Th8, the scene determination is a colorful vivid scene, and the process proceeds to the colorful vivid process of S109.

  As described above, the imaging apparatus according to the present embodiment acquires color information of a subject, detects a colorful scene with a large number of colors and a vivid scene with a small number of colors according to the number of hues with high saturation, Perform signal processing according to each scene. Accordingly, it is possible to shoot a colorful subject and a monochromatic and vivid subject with more color without bothering the user. In addition, it is possible to better reproduce subtle color differences between similar colors in a single color vivid scene with a small number of colors.

  In the present embodiment, the processing for enhancing the vividness by increasing the saturation or widening the hue range of the image data determined to be a vivid scene has been described, but the present invention is not limited to this. That is, it can also be applied to processing that suppresses vividness by lowering the saturation or narrowing the hue range for a vivid scene.

  In the above embodiment, whether or not the scene is vivid is determined based on two pieces of information, that is, the average saturation value and the size of the high saturation area, but the determination method of the bright scene is limited to this. It is not a thing. For example, a vivid scene may be determined based on saturation information in a region with the highest saturation in the image.

(Embodiment 2)
In the present embodiment, the monochrome vivid scene detection process and the colorful vivid scene detection process performed by the camera microcomputer 111 in the imaging apparatus according to the first embodiment are replaced as follows. A monochrome vivid scene detection process and a colorful vivid scene detection process performed by the camera microcomputer 111 in the imaging apparatus of the present embodiment will be described with reference to the flowchart of FIG.

In the first embodiment, the case where the threshold values Th1, Th2, Th3, Th4, Cmin, and Cmax used in the monochrome bright scene detection process are preset constants has been described. In the present embodiment, the threshold values Th1, Th2, Th3, Th4, Cmin, and Cmax are variables, and the values change according to the zoom state at the time of shooting. When the zoom is at the wide end, the threshold values used in the single color vivid scene detection process of the present embodiment are Th1w, Th2w, Th3w, Th4w, Cminw, and Cmaxw, respectively. On the other hand, when the zoom is at the telephoto end, Th1t, Th2t, Th3t, Th4t, Cmint, and Cmaxt are set. In the case of other zoom areas, a value between the threshold values at the wide end and the tele end is set according to the zoom magnification. Furthermore, the relationship between the threshold values Th1, Th2, Th3, Th4, Cmin, and Cmax in the first embodiment is as follows.
Th1w ≤ Th1 ≤ Th1t
Th2w ≦ Th2 ≦ Th2t
Th3w ≤ Th3 ≤ Th3t
Th4w ≤ Th4 ≤ Th4t
Cminw = Cmin = Cmint
Cmaxw = Cmax = Cmaxt

In the first embodiment, the case where the threshold values Th5, Th6, Th7, Th8, and C used in the colorful vivid scene detection process are preset constants has been described. In this embodiment, threshold values Th5, Th6, Th7, Th8, and C are variables, and the values change according to the zoom state at the time of shooting. The threshold values used in the colorful vivid scene detection processing of this embodiment are Th5w, Th6w, Th7w, Th8w, and Cw, respectively, when the zoom is at the wide end. On the other hand, when the zoom is at the telephoto end, Th5t, Th6t, Th7t, Th8t, and Ct are set. In the case of other zoom areas, a value between the threshold values at the wide end and the tele end is set according to the zoom magnification. Furthermore, the relationship between the threshold values Th5, Th6, Th7, Th8, and C in the first embodiment is as follows.
Th5w ≤ Th5 ≤ Th5t
Th6w ≤ Th6 ≤ Th6t
Th7w ≤ Th7 ≤ Th7t
Th8w ≤ Th8 ≤ Th8t
Cw = C = Ct

  In the present embodiment, the scene detection threshold is changed according to the zoom magnification. Specifically, the threshold is changed so that a monochromatic vivid scene or a colorful vivid scene is more easily detected as the zoom at the time of shooting is wider, that is, the zoom magnification is smaller. Accordingly, it is possible to prevent the zoom from becoming wide and difficult to detect as a vivid scene, and conversely, the zoom from being telephoto and being detected as a vivid scene too much. It should be noted that this is the same as the monochromatic vivid scene detection process and the colorful vivid scene detection process of the first embodiment, except that the scene detection threshold changes according to the zoom state at the time of shooting.

  As described above, by changing the threshold for detecting a vivid scene according to the zoom magnification, it is possible to make the change in color correction for the vivid scene more smoothly follow the zoom operation.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

The present invention relates to an image processing apparatus and a control method therefor, and more particularly to an image quality correction technique for an image processing apparatus.

SUMMARY An advantage of some aspects of the invention is that it provides an image processing apparatus and a control method thereof capable of performing appropriate image quality settings for a colorful scene without bothering a user.

According to one aspect of the present invention, a shooting scene of a subject having a color number less than a predetermined value and a vivid scene, and a color number exceeding a predetermined value, depending on the saturation and the number of hues of a video signal obtained by shooting What is claimed is: 1. An image processing apparatus comprising: detection means for detecting a large number of vivid scenes; and correction means for performing color correction processing on the video signal according to a shooting scene detected by the detection means. Provided.

ADVANTAGE OF THE INVENTION According to this invention, the image processing apparatus which can perform an appropriate image quality setting with respect to a colorful scene, and its control method are provided, without annoying a user's hand.

Claims (9)

Detection that detects vivid scenes with fewer colors than the predetermined value and vivid scenes with more than the predetermined number of colors as subject shooting scenes based on the saturation and the number of hues of the video signal obtained by shooting Means,
Correction means for performing color correction processing according to the shooting scene detected by the detection means on the video signal;
An imaging device comprising:   2. The correction unit according to claim 1, wherein when the detection unit detects a vivid scene with the number of colors larger than a predetermined value, the correction unit performs a color correction process for increasing the saturation of the video signal. The imaging device described.   The imaging apparatus according to claim 2, wherein the correction unit performs a color correction process for increasing the saturation of the video signal using a correction value corresponding to a spread of a hue histogram acquired from the video signal.   When the detection unit detects a vivid scene with a small number of colors, the correction unit performs a color correction process to widen a main limited hue range of the video signal. The imaging device according to any one of claims 1 to 3.   5. The correction unit according to claim 4, wherein the correction unit increases the correction value in the color correction process as the degree of concentration in the main limited hue in the hue histogram acquired from the video signal is higher. Imaging device.   When the detection unit detects a vivid scene with a small number of colors, the correction unit expands the hue range so that the spread of the hue histogram acquired from the video signal is equal to or greater than a preset threshold. The image pickup apparatus according to claim 1, wherein color correction processing is performed.   The detection means sets the threshold values for the saturation and the number of hues for detecting the photographic scene as the zoom magnification is smaller, respectively, and the number of colors is smaller than a predetermined value and the vivid scene and the number of colors are predetermined. The imaging apparatus according to claim 1, wherein the imaging apparatus is changed so that a scene that is brighter than the value is easily detected. A method for controlling an imaging apparatus,
Detection that detects vivid scenes with fewer colors than the predetermined value and vivid scenes with more than the predetermined number of colors as subject shooting scenes based on the saturation and the number of hues of the video signal obtained by shooting Process,
A correction step for performing color correction processing according to the shooting scene detected in the detection step for the video signal;
A method for controlling an imaging apparatus, comprising:   The program for functioning a computer as each means which the imaging device of any one of Claims 1 thru | or 7 has.

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