JP2010147689A - Imaging apparatus and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in a prior art, a photographer not necessarily obtains an image with desired characteristics. <P>SOLUTION: An imaging apparatus has: imaging parts (103, 104) which captures images by an optical system (102); a display part (108) which displays the images by imaging signals obtained by the imaging parts (103, 104); setting parts (112, 106) for setting target values of the imaging signals at their positions in association with specific positions in the images; and correction parts (105, 106) which correct the imaging signals obtained by the imaging parts (103, 104) based on the target values set by the setting parts (112, 106). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for correcting the output of a captured image.

Conventionally, as a method of obtaining an image with the dynamic range and gradation characteristics desired by the photographer, an image is shot with a dynamic range wider than the dynamic range required for the reproduced image or print after shooting. And a method of correcting to a desired characteristic at the time of printing is known (for example, see Patent Document 1).
Japanese Patent No. 3959581

  However, in the conventional technology, it is not only necessary to shoot with a wide dynamic range at the time of shooting, but the method of adjusting to the desired characteristics while viewing the reproduced image and histogram etc. after shooting is the gradation reproducibility built in the camera However, there is a problem that the characteristics of the obtained image are not necessarily what the photographer desires.

  An object of the present invention is to provide an imaging apparatus and an image processing program capable of obtaining an image having characteristics desired by a photographer.

  The present invention solves the above problems by the following means. For ease of understanding, reference numerals corresponding to the drawings showing an embodiment of the present invention are given and described, but the present invention is not limited to this.

  The invention according to claim 1 is an imaging unit (103, 104) that captures an image by the optical system (102), and a display unit that displays an image based on the imaging signal obtained by the imaging unit (103, 104). 108), a setting unit (112, 106) for setting a target value of the imaging signal at the position in association with a specific position in the image, and a target value set by the setting unit (112, 106) And a correction unit (105, 106) for correcting the imaging signal obtained by the imaging unit (103, 104).

  According to a second aspect of the present invention, the setting unit (112, 106) sets a target value of the imaging signal related to a first position to be a highest light and a second position to be a deep shadow in the image. It is characterized by.

  The invention according to claim 3 is characterized in that the first target value related to the first position and the second target value related to the second position each have a predetermined allowable range.

  According to a fourth aspect of the present invention, the correction unit (105, 106) is configured such that the imaging signal at the first position and the imaging signal at the second position of an image captured by the imaging unit (103, 104). When at least one of the two is not within the allowable range, a plurality of images with different exposure conditions are captured by the imaging unit (103, 104), and the imaging signal is corrected based on the plurality of images. To do.

  The invention according to claim 5 is characterized in that the correction section (105, 106) corrects a plurality of images obtained at a plurality of different exposure times.

  The invention according to claim 6 is characterized in that the correction unit (105, 106) corrects a dynamic range of the image pickup signal obtained by the image pickup unit (103, 104).

  The invention according to claim 7 is characterized in that the setting unit (112, 106) sets a target value of the imaging signal related to a third position which is a halftone in the image.

  The invention according to claim 8 is characterized in that the correction unit (105, 106) corrects a dynamic range and a gradation characteristic in the imaging unit (103, 104).

  The invention according to claim 9 is a display procedure (S102) for displaying an image based on an image signal on the display unit, and the image signal at the position in association with a specific position in the image displayed on the display unit. And a correction procedure (S105 to S114) for correcting the image signal based on the target value set in the setting procedure.

  Note that the configuration described with reference numerals may be improved as appropriate, or at least a part thereof may be replaced with another component.

  The imaging apparatus and the image processing program according to the present invention can obtain an image having characteristics desired by the photographer.

  Hereinafter, an imaging apparatus and an image processing program according to embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus 101 according to the first embodiment. The imaging apparatus 101 includes an optical system 102, an imaging element 103, an AFE (analog front end) circuit 104, an image processing unit 105, a CPU (central processing unit) 106, a buffer memory 107, a monitor 108, and a memory. 109, a recording I / F (interface) 110, a memory card 111, an operation member 112, and a PC (personal computer) I / F 113. A personal computer (PC) 114 can be connected to the PCI / F 113.

  FIG. 2 is an explanatory diagram showing the appearance of the imaging apparatus 101. In FIG. 2, the housing of the image pickup apparatus 101 includes a power button 201, a release button 202, a zoom button 203, a cross key 204 (up key 204a, down key 204b, left key 204c, right key 204d), and confirm (OK). Operation buttons such as a button 205 and a shooting mode selection dial 206 are arranged. These operation buttons are included in the operation member 112 in FIG.

  Hereinafter, the configuration of the imaging apparatus 101 according to the present embodiment will be described in order with reference to FIGS. 1 and 2. Note that the imaging apparatus 101 according to the present embodiment has a “manual gradation photographing mode” for photographing an image having an image characteristic (dynamic range or gradation characteristic) desired by the photographer. In the imaging apparatus 101 according to the present embodiment, the imaging element 103 and the AFE circuit 104 constitute an imaging unit, and the monitor 108 corresponds to a display unit that displays an image captured by the imaging unit. The setting unit that associates and sets the position in the image and the target value of the output of the image signal at this position includes the operation member 112 and the CPU 106, and uses the target value of the image signal set by the setting unit as a reference. A correction unit that corrects captured image characteristics includes an image processing unit 105 and a CPU 106.

  In FIG. 1, the optical system 102 includes a plurality of lenses such as a focus lens and a zoom lens. The subject light incident on the optical system 102 forms an image on the light receiving surface of the image sensor 103.

  The image sensor 103 is configured by a CMOS image sensor or the like in which a plurality of photoelectric conversion units are two-dimensionally arranged on the light receiving surface. The photoelectric conversion unit converts the signal into an electrical signal corresponding to the amount of imaged subject light, and outputs the electrical signal to the AFE circuit 104.

  The AFE circuit 104 performs noise removal of the electric signal output from the image sensor 103, gain adjustment according to the set sensitivity, and the like. Further, the analog electrical signal is A / D converted into digital image data and output to the image processing unit 105.

  The image processing unit 105 performs image processing (white balance processing, color correction processing, gradation processing, etc.) on the image data output from the AFE circuit 104 in accordance with a command from the CPU 106. Further, in the “manual gradation photographing mode”, image analysis processing for determining whether or not the output value of the image signal at a predetermined position is within an allowable range, dynamic range expansion / compression processing, or gradation characteristics Perform correction processing. Note that image data input from the AFE circuit 104 by the image processing unit 105 is temporarily stored in the buffer memory 107 via the CPU 106, and the image processing unit 105 performs various image processing on the buffer memory 107. Further, the processed image data is also temporarily stored in the buffer memory 107.

  The CPU 106 operates according to a program stored therein in advance, and controls the entire operation of the imaging apparatus 101. For example, the CPU 106 performs AF (autofocus) control, AE (automatic exposure) control, auto white balance control, and the like. Then, the position of the focus lens of the optical system 102 is varied according to the focus position. Similarly, the position of the zoom lens is changed according to the operation of the zoom button 203 included in the operation member 112. In addition, the CPU 106 displays the image data temporarily stored in the buffer memory 107 on the monitor 108. Alternatively, the CPU 106 reads captured image data stored in the memory card 111 into the buffer memory 107 and displays it on the monitor 108.

  Here, the imaging apparatus 101 according to the present embodiment displays on the monitor 108 a subject image that is continuously captured in time by the imaging element 103 as a live view image. The live view image is captured from the image sensor 103 to the buffer memory 107 via the AFE circuit 104 and the image processing unit 105 and displayed on the monitor 108 like a moving image, as in the case of the main shooting for shooting a normal still image. The The live view image is an image used by the photographer to confirm the subject image. Generally, the live view image is a simple image having a coarser resolution than the actual captured image. The photographer determines the shooting composition by looking at the live view image displayed on the monitor 108 and presses the release button 202 included in the operation member 112. During normal shooting other than the “manual gradation shooting mode”, when the photographer presses the release button 202 included in the operation member 112, the actual captured image captured by the image sensor 103 is temporarily stored in the buffer memory 107. The image processing unit 105 performs white balance processing, color correction processing, gradation processing (normal gamma conversion processing), and the like, and then is stored in the memory card 111 attached to the recording I / F 110 via the CPU 106. The

  The buffer memory 107 is used as a buffer when the image processing unit 105 performs image processing. The buffer memory 107 is also used as a display buffer that temporarily stores image data to be displayed on the monitor 108 by the CPU 106.

  The monitor 108 is composed of a liquid crystal monitor or the like, and displays images (live view images and actual captured images) output from the CPU 106, operation menus, and the like. Further, the CPU 106 can display graphics, characters, and the like superimposed on the image displayed on the monitor 108. Further, a touch panel type monitor may be adopted as the monitor 108 so that it can be operated with a touch panel instead of the operation buttons of the operation member 112.

  The memory 109 is configured by a nonvolatile memory such as a flash memory. The memory 109 stores various parameters necessary for operation, such as shooting mode setting contents and exposure control values of the imaging apparatus 101. These parameters include parameters stored in advance at the time of manufacturing the imaging apparatus 101, parameters set by the photographer using the setting menu, and the like. In particular, in the present embodiment, for example, a position in the live view image, a target value, or an allowable range of the target value are stored as parameters in the “manual gradation shooting mode”. The “manual gradation shooting mode” will be described in detail later.

  The recording I / F 110 has a connector (not shown), and the memory card 111 is connected to the connector. Then, the image data output from the CPU 106 is written into the memory card 111, and the image data stored in the memory card 111 is read out to the CPU 106.

  The memory card 111 is composed of a nonvolatile memory such as a flash memory. Image data captured by the imaging apparatus 101 is stored. In addition, a memory card 111 in which captured images are stored can be attached to a personal computer, and image processing can be performed on the captured images on the personal computer.

  As illustrated in FIG. 2, the operation member 112 includes buttons for the photographer to operate the imaging apparatus 101. The photographer operates the imaging apparatus 101 using these operation buttons. The operation information of each operation button is output to the CPU 106, and the CPU 106 controls the operation of the entire imaging apparatus 101 according to the operation information of the operation button. For example, when the photographer operates the photographing mode selection dial 206 of the operation member 112 to select “manual gradation photographing mode”, the CPU 106 starts processing of “manual gradation photographing mode”.

  The PC (personal computer) I / F 113 includes a USB (general-purpose serial bus) interface, a LAN (local area network), and the like. The PC 114 can read out image data stored in the memory card 111 attached to the imaging apparatus 101 via the PCI / F 113, and conversely write image data into the memory card 111. Alternatively, the CPU 106 can change various parameters stored in the memory 109 in accordance with commands from the PC 114. Further, the remote PC 114 and the imaging device 101 are connected via a LAN or the Internet, the live view image is sent from the imaging device 101 to the PC 114, and the processing of the “manual gradation shooting mode” is executed on the PC 114 side. Thus, it is also possible to take an image of the output characteristics desired by the photographer with the imaging device 101.

  Next, the “manual gradation shooting mode” of the imaging apparatus 101 according to the present embodiment will be described in detail. The photographer uses the photographing mode selection dial 206 of the operation member 112 to select “manual gradation photographing mode”. In the “manual gradation shooting mode”, the photographer operates the cross key 204 while viewing the live view image displayed on the monitor 108, and sets the position (first position) on the screen where the highest light (maximum luminance value) is desired. The position (second position) on the screen to be used for the deep shadow (minimum luminance value) is designated. Furthermore, a position (third position) on the screen where halftone is desired may be designated. This is shown in FIG.

  On the enlarged screen of the live view image of the monitor 108 in FIG. 2, the highest light point H301, the deep shadow point L302, and the halftone point M303 are displayed superimposed on the live view image.

  For example, when the CPU 106 starts the “manual gradation shooting mode”, the symbol H of the highest light point H301 is first superimposed on the live view image and blinked. Then, the photographer uses the up key 204a, the down key 204b, the left key 204c, and the right key 204d of the cross key 204 to move the symbol H of the highest light point H301 up and down, left and right, and to specify the position on the live view image to be designated. Move to. Therefore, when the photographer presses the OK button 205, the CPU 106 reads the position on the live view image where the symbol H of the highest light point H301 is present and temporarily stores it in the memory 109. Then, the blinking of the symbol H of the highest light point H301 on the live view image is stopped and fixed to the display state.

  Next, the CPU 106 superimposes the symbol L of the deep shadow point L302 on the live view image and blinks it. Then, similarly to the position designation of the highest light point H301, the photographer uses the up key 204a, down key 204b, left key 204c, and right key 204d of the cross key 204 to move the symbol L of the deep shadow point L302 up, down, left, and right. Move to the position on the live view image you want to specify. Therefore, when the photographer presses the OK button 205, the CPU 106 reads the position on the live view image where the symbol L of the deep shadow point L302 is present and temporarily stores it in the memory 109. Then, the flashing of the symbol L of the deep shadow point L302 on the live view image is stopped and fixed to the display state.

  Subsequently, when designating the halftone point M303, the CPU 106 superimposes the symbol M of the halftone point M303 on the live view image and blinks it. Then, similar to the designation of the position of the symbol H of the highest light point H301 and the designation of the position of the symbol L of the deep shadow point L302, the photographer uses the upper key 204a, the lower key 204b, the left key 204c, and the right key 204d of the cross key 204. The symbol M of the halftone point M303 is moved up, down, left and right to move to a position on the live view image to be designated. Therefore, when the photographer presses the OK button 205, the CPU 106 reads the position on the live view image where the symbol M of the halftone point M303 is present and temporarily stores it in the memory 109.

  In this way, the photographer designates the position of each point of the highest light point H301, the deep shadow point L302, and the halftone point M303. At this time, if the monitor 108 is constituted by a touch panel, the position of each point can be easily specified.

  Here, the position information represents, for example, vertical and horizontal pixel positions on the screen of the monitor 108 by (x, y) coordinates. In this case, assuming that the number of vertical and horizontal pixels of the monitor 108 is 320 × 240, the position of the highest light point H is coordinates H (220, 200), the position of the deep shadow point L is coordinates L (80, 60), and halftones. The position of the point M is expressed as coordinates M (240, 120). These position coordinates are stored in the memory 109.

  Next, setting of the target value of the image signal at the highest light point, the deep shadow point, and the halftone point will be described. The target value is set by, for example, operating the operation member 112 to display the “manual gradation photographing mode” menu screen on the monitor 108 and inputting the target value of each point. Note that the method of inputting the target value using the cross key 204 is performed by using the left key 204c and the right key 204d of the cross key 204 on the menu screen of the “manual gradation shooting mode” as shown in FIG. Select one of the point items (highest light point, deep shadow point, halftone point) for which you want to set a value. For example, the selected item is surrounded by a thick frame.

  In the case of FIG. 3, an item (highest light point) surrounded by a thick frame is selected. In this state, each time the upper key 204a or the lower key 204b of the cross key 204 is pressed, the target value of the selected item is raised or lowered. When the target value desired by the photographer is reached, the OK button 205 is pressed to Determine the target value for. Next, when setting the target value of the deep shadow point, similarly, the item of the deep shadow point is selected using the left key 204c and the right key 204d of the cross key 204, and the upper key 204a or the lower key of the cross key 204 is further selected. The target value of the deep shadow point is selected using the key 204b. Also, the target value can be set for halftone points by the same operation.

  Next, shooting processing in the “manual gradation shooting mode” of the imaging apparatus 101 according to the present embodiment will be described in detail with reference to the flowchart of FIG. Note that the flowchart of FIG. 4 operates according to a program incorporated in the CPU 106 in advance, and appropriately instructs the image processing unit 105 to perform image processing.

  (Step S101) The photographer uses the photographing mode dial 206 of the operation member 112 to select “manual gradation photographing mode”. At this time, it is preferable to fix the camera to a tripod.

  (Step S <b> 102) The CPU 106 displays a live view image captured by the image sensor 103 on the display unit 108.

  (Step S103) As described above, the photographer sets the positions and target values of the highest light point, deep shadow point, and halftone point. The setting contents are stored in the memory 109.

  (Step S <b> 104) The CPU 106 determines whether or not the photographer has pressed the release button 202. Here, the CPU 106 waits until the release button 202 is pressed, and proceeds to step S105 when the release button 202 is pressed. If the shooting mode dial 206 is changed or another menu screen is selected even if the release button 202 is not pressed, the “manual gradation shooting mode” is terminated and the process exits from this flowchart.

  (Step S105) The CPU 106 performs a photographing process. Specifically, image data captured by the image sensor 103 is temporarily stored in the buffer memory 107, and white balance processing, color correction processing, gradation processing, and the like are performed by the image processing unit 105. Note that in normal shooting processing, image data processed by the image processing unit 105 is subjected to image compression processing such as JPEG, and is stored in the memory card 111 attached to the recording I / F 110 via the CPU 106. However, in the “manual gradation photographing mode”, the buffer memory 107 is still temporarily stored at this time.

  (Step S <b> 106) The CPU 106 instructs the image processing unit 105 to perform image analysis processing. Upon receiving the command, the image processing unit 105 performs the highest light point, deep shadow point, and halftone point stored in the memory 109 in step S103 on the image data stored in the buffer memory 107 in step S105. The output value of the image signal is obtained. The output value of the image signal at each position may be the output value of the image signal of one pixel corresponding to each position, or the average output of the image signals of a plurality of pixels around the pixel corresponding to each position. A value may be used.

  (Step S107) The CPU 106 outputs the output value of the image signal at each position of the highest light point and deep shadow point obtained in Step S106 within the allowable range of the output value of the image signal set in the imaging apparatus 101 in advance. It is determined whether or not. If it is within the allowable range, the process proceeds to step S114. If it is not within the allowable range, the process proceeds to step S108. In this processing step, it is not determined whether the output value of the halftone point image signal is within the allowable range, but the output value of the halftone point image signal is also within the allowable range. It may be determined whether or not it is.

  Here, an example in which the output value of the image signal at each position of the captured image is within the allowable range of the target value set previously will be described with reference to FIG. In FIG. 5, the target values of the highest light point H301, deep shadow point L302, and halftone point M303 set in the live view image 251 are the target value of the highest light point H = 250, the target value of the deep shadow point L = 10. Target value of halftone point M = 128. Further, the allowable ranges of the output values of the image signals of the highest light point H301 and the deep shadow point L302 are ± 20, respectively. At this time, assuming that the output values of the image signal at each position of the actual captured image 252 captured in step S105 are, for example, a highest light point H = 240, a deep shadow point L = 20, and a halftone point M = 140. Since the output values of the image signals of the highest light point H301 and the deep shadow point L302 of the captured image 252 are within the allowable ranges of the respective target values, the process proceeds to step S114.

  Next, an example in which the output value of the image signal at each position of the actual captured image is not within the allowable range of the target value set previously will be described with reference to FIG. In FIG. 6, the target values of the highest light point H301, the deep shadow point L302, and the halftone point M303 set in the live view image 254 are the target value of the highest light point H = 250, the target value of the deep shadow point L = 10. Target value of halftone point M = 128. Further, the allowable ranges of the output values of the image signals of the highest light point H301 and the deep shadow point L302 are ± 20, respectively. At this time, if the output value of the image signal at each position of the actual captured image 255 captured in step S105 is, for example, a highest light point H = 220, a deep shadow point L = 20, and a halftone point M = 110. Since the output value of the image signal at the highest light point H301 of the photographed image 255 is not within the allowable range of each target value, the process proceeds to step S108. If the output value of at least one image signal of the highest light point H301 and the deep shadow point L302 is not within the allowable range of the target value, the process proceeds to step S108.

  As described above, in step S107, whether or not the output values of the image signals of both the highest light point H301 and the deep shadow point L302 of the actual captured image captured in step S105 are within the allowable ranges of the respective target values. Is determined.

  (Step S108) The CPU 106 calculates an exposure correction amount for the output value of the image signal at the highest light point position or the output value of the image signal at the deep shadow point position of the image taken in step S105 to be the respective target values. To do. At this time, the points that were within the allowable range in step S107 are to be calculated. Here, the exposure correction amount is calculated, for example, by calculating in advance from the design value or actual measurement value of the imaging device 101 how much the output value of the image signal of the image to be captured changes when the shutter speed is increased or decreased by one step. It is stored in the memory 109 when the apparatus 101 is manufactured.

  For example, when the output value of the image signal of the image to be captured is increased or decreased by about 10 when the shutter speed is increased or decreased by one step, and the output value of the image signal of the image captured with respect to the target value is 250, Just lower the shutter speed by three levels. For example, when the shutter speed when the output value of the image signal of the image is 220 is 1/500 seconds, the shutter speed after exposure correction is 1/60 seconds, which is three steps slower. On the contrary, when the output value of the image signal of the image taken with respect to the target value 10 is 40, the shutter speed may be increased by three stages. For example, the shutter when the output value of the image signal of the image is 10 When the speed is 1/500 seconds, the shutter speed after exposure correction is 1/4000 seconds, which is three steps faster. In this way, the CPU 106 calculates the exposure correction amount for the output value of the image signal at the highest light point position or the output value of the image signal at the deep shadow point position of the image taken in step S105 to be the target value. To do.

  In this embodiment, exposure correction is performed at the shutter speed. However, exposure correction may be performed by gain adjustment of the AFE circuit 104. Further, although exposure correction may be performed with the aperture, it is not preferable for a subject in which a difference in depth of field is conspicuous in images before and after exposure correction.

  (Step S109) The CPU 106 changes the exposure conditions (shutter speed, ISO sensitivity (gain adjustment), aperture value, etc.) so that the exposure correction amount calculated in step S108 is obtained.

  (Step S <b> 110) The CPU 106 automatically performs a photographing process and newly captures a main captured image. Note that the image data captured by the image sensor 103 is temporarily stored in the buffer memory 107, and the image processing unit 105 performs white balance processing, color correction processing, gradation processing, and the like. For example, the actual captured image 256 in FIG. 6 is the actual captured image newly captured in step S110. At this time, the actual captured image 255 captured in step S105 is still stored in the buffer memory 107.

  (Step S111) The CPU 106 instructs the image processing unit 105 to perform image analysis processing in the same manner as in Step S106. Upon receiving the command, the image processing unit 105 outputs the output value of the image signal at each position of the highest light point, deep shadow point, and halftone point with respect to the image data stored in the buffer memory 107 photographed in step S110. Ask for. The method for obtaining the output value of the image signal at each position is the same as in step S106. For example, the output value of the image signal at each position of the actual captured image 256 in FIG. 6 is a highest light point H = 250, a deep shadow point L = 50, and a halftone point M = 140.

  (Step S112) Similar to step S107, the CPU 106 allows an allowable range of a target value in which the output values of the image signal at each position of the highest light point and deep shadow point obtained in step S111 are set in the imaging apparatus 101 in advance. It is determined whether it is inside. If it is within the allowable range, the process proceeds to step S113. If it is not within the allowable range, the process returns to step S108. Here, the determination as to whether or not it is within the allowable range is made only for the points that are not within the allowable range at step S107, and the points that were within the allowable range at step S107 are within the allowable range. It is not determined whether or not there is.

  For example, it is determined whether only the output value of the image signal at the highest light point H that is not within the allowable range in the actual captured image 255 of FIG. 6 is within the allowable range (± 20) of the target value (250). I do. The output values of the image signal of the actual captured image 256 newly captured in step S110 are the highest light point H = 250, the deep shadow point L = 50, and the halftone point M = 140. It is determined that the output value is within the allowable range (± 20) of the target value (250), and the process proceeds to step S113.

  If the output value of the image signal at the highest light point H of the actual captured image 256 is not within the allowable range of the target value, the process returns to step S108, and the exposure correction amount is again set based on the actual captured image 256. Calculate and execute the processing from step S109 to step S111. In this way, the same processing is repeated until the output value of the image signal at the point that does not fall within the allowable range in step S107 falls within the allowable range of the target value. For example, if both the highest light point and the deep shadow point are not within the allowable range of the target value in step S107, the actual captured image is output until the output values of the image signals at both points are within the allowable range of the target value. Shoot. At this time, the output value of the image signal of the high light point is within the allowable range of the target value, and the output value of the image signal of the deep shadow point is within the allowable range of the target value. It is only necessary to obtain two images of the actual captured image.

  (Step S113) The CPU 106 instructs the image processing unit 105 to perform image composition processing. Receiving the command, the image processing unit 105 combines the actual captured image captured in step S105 with at least one actual captured image captured in the repeated processing from step S108 to step S112 to produce one synthesized image. create. At this stage, the output value of the image signal at each position of the highest light point and deep shadow point of the created composite image is within the allowable range of each target value, but does not necessarily match the target value. Not necessarily. For example, as shown in FIG. 6, when two main photographic images of the main photographic image 255 and the main photographic image 256 are combined to create one composite image 257, an image of the highest light point H of the composite image 257. Since the output value of the signal is 250, it matches the target value (250). However, the output value of the image signal of the deep shadow point L of the composite image 257 is 20, so it is within the allowable range but slightly different from the target value (10). It's off. Similarly, the output value of the image signal of the halftone point M of the composite image is 130, which is slightly different from the target value (128).

  (Step S114) The CPU 106 corrects the deviation between the output value of the image signal at each position and the respective target value, and expands the dynamic range so that the output value of the image signal at each position matches the respective target value. / The image processing unit 105 is instructed to perform compression processing and gradation processing for correcting gradation characteristics.

  For example, a case will be described in which a Yes determination is made in the determination processing in step S107. In the example of FIG. 5, the corrected image 253 is created by performing dynamic range expansion / compression processing and gradation processing for correcting gradation characteristics on the actual captured image 252. As a result, the output values of the image signal of the corrected image 253 are the highest light point H = 250, the deep shadow point L = 10, and the halftone point M = 128, and an image according to the target value of each point can be obtained.

  A case where No is determined in the determination processing in step S107 will be described. For example, as shown in FIG. 6, dynamic image expansion / compression processing and gradation processing for correcting gradation characteristics are performed on the composite image 257 to create a corrected image 258. As a result, the output value of the image signal of the corrected image 258 becomes the highest light point H = 250, the deep shadow point L = 10, and the halftone point M = 128, and an image according to the target value of each point can be obtained.

  Here, dynamic range expansion / compression processing will be described with reference to FIG. FIG. 7A shows an example of dynamic range conversion processing in the case of 8-bit gradation (256 gradations from 0 to 255). In FIG. 7A, the range of the dynamic range desired by the photographer is set such that the target value of the high light point is 250 and the target value of the deep shadow point is 10, as indicated by the dynamic range 401. On the other hand, it is assumed that the dynamic range 402 obtained from the actual captured image or the synthesized image is the output value of the image signal of the highest light point = 225 and the output value of the image signal of the deep shadow point = 30. In this case, the output value (30) of the image signal of the deep shadow point becomes the target value (10) so that the output value (225) of the image signal of the highest light point becomes the target value (250). Increase the scale (enhance the dynamic range). The output value of the image signal between the output value (30) of the image signal and the output value (225) of the image signal is also calculated according to the ratio.

  Alternatively, it is assumed that the dynamic range 402 of the photographed main photographed image or composite image is the output value of the image signal of the highest light point = 255 and the output value of the image signal of the deep shadow point = 0. In this case, the output value (0) of the image signal of the deep shadow point becomes the target value (10) so that the output value (255) of the image signal of the high light point becomes the target value (250). Compress the scale (dynamic range compression). The output value of the image signal between the output value (0) of the image signal and the output value (255) of the image signal is also calculated according to the ratio.

  In this way, the image processing unit 105 receives the command from the CPU 106 and performs processing for expanding / compressing the dynamic range of the captured real image or composite image.

  Next, gradation processing for correcting gradation characteristics will be described with reference to FIG. The gradation processing is processing for correcting the gradation characteristics so that the output value of the image signal of the halftone point becomes the target value. FIG. 7B shows a processing example for correcting the output value of the image signal of the halftone point to the target value. FIG. 7B shows an example in which the gradation characteristics are corrected after the dynamic range expansion / compression processing described in FIG. 7A is performed, and the horizontal axis indicates the output value of the image signal before correction. The vertical axis represents the output value of the corrected image signal. In FIG. 7B, the output value of the image signal of the highest light point and the output value of the image signal of the deep shadow point are adjusted to the respective target values by the dynamic range expansion / compression processing described in FIG. For example, it is assumed that the gradation characteristic 404 is obtained. Here, when the output value of the image signal at the halftone point of the gradation characteristic 404 is 140, the CPU 106 instructs the image processing unit 105 to correct the target value to 128. Note that the gradation characteristic 405 is a gradation characteristic after correction. Here, the method of creating the corrected gradation characteristic 405 from the uncorrected gradation characteristic 404 is, for example, by using a curve function such as a Bezier curve based on three points of a highest light point, a deep shadow point, and a halftone point. The output value of the image signal between the points may be obtained by using, or the output value of the image signal between the points may be obtained by a simple approximate straight line. In this way, the image processing unit 105 receives a command from the CPU 106 and performs a correction process on the gradation characteristics of the captured real image or composite image.

  (Step S115) The CPU 106 stores the image data that has been subjected to the dynamic range expansion / compression processing and the gradation characteristic correction processing in Step S114 in the memory card 111 via the recording I / F 110. Alternatively, it is displayed on the monitor 108. For example, in the case of FIG. 5, the corrected image 253 is stored on the memory card 111 or displayed on the monitor 108, and in the case of FIG. 6, the corrected image 258 is stored on the memory card 111 or displayed on the monitor 108.

  (Step S116) The CPU 106 ends the photographing process in the “manual gradation photographing mode”.

  As described above, the imaging apparatus 101 according to the present embodiment has the “manual gradation imaging mode” for capturing an image having characteristics (dynamic range and gradation characteristics) desired by the photographer. It is possible to shoot an image that has been corrected to target values of three points of the highest light point, deep shadow point, and halftone point specified on the live view image.

  In the present embodiment, the target values of the three points of the highest light point, the deep shadow point, and the halftone point are set, but only two points of the highest light point and the deep shadow point may be set. In any case, by applying the configuration and processing described in the present embodiment, it is possible to easily capture an image having characteristics desired by the photographer.

  In addition, the imaging apparatus 101 according to the present embodiment can be applied not only to a still camera but also to all apparatuses that can capture images including a video camera, a camera-equipped mobile phone, and the like.

  Furthermore, although the imaging apparatus 101 has been described in the present embodiment, as illustrated in FIG. 1, the imaging apparatus 101 and the PC 114 that corrects output characteristics of an image captured by the imaging apparatus 101 may be configured as an image processing apparatus. I do not care. For example, a camera system that enables an imaging apparatus 101 and a PC 114 installed at geographically distant locations to be connected via the Internet, and performs imaging while monitoring an image captured by the imaging apparatus 101 as a live view image on the PC 114. Can be realized.

  As mentioned above, although this invention was demonstrated in detail, said embodiment is only an example of this invention and this invention is not limited to this. Obviously, modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows the structure of the imaging device 101 which concerns on this embodiment. It is explanatory drawing which shows the external appearance of the imaging device 101 which concerns on this embodiment. It is explanatory drawing which shows the mode of the setting menu screen of target value. 6 is a flowchart illustrating an operation of the imaging apparatus 101 according to the present embodiment. It is explanatory drawing which shows the process example in the case of being in the tolerance | permissible_range. It is explanatory drawing which shows the process example when it does not enter in the tolerance | permissible_range. It is explanatory drawing which shows the example of the expansion / compression process of a dynamic range, and the correction process of a gradation characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Imaging device 102 ... Optical system 103 ... Imaging element 104 ... AFE circuit 105 ... Image processing part 106 ... CPU
107 ... Buffer memory 108 ... Monitor 109 ... Memory 110 ... Recording I / F
111 ... Memory card 112 ... Operation member 113 ... PCI / F 114 ... PC
201 ... Power button 202 ... Release button 203 ... Zoom button 204 ... Cross key 204a ... Up key 204b ... Down key 204c ... Left key 204d ... Right key 205 ..Confirmation (OK) button 206 ... Shooting mode selection dial

Claims (9)

An imaging unit for imaging an image by an optical system;
A display unit for displaying an image based on an imaging signal obtained by the imaging unit;
A setting unit that sets a target value of the imaging signal at the position in association with a specific position in the image;
An imaging apparatus comprising: a correction unit that corrects the imaging signal obtained by the imaging unit with reference to the target value set by the setting unit. The imaging device according to claim 1,
The said setting part sets the target value of the said image pick-up signal regarding the 1st position used as highest light in the said image, and the 2nd position used as deep shadow. The imaging device characterized by the above-mentioned. The imaging device according to claim 2,
The first target value related to the first position and the second target value related to the second position each have a predetermined allowable range. The imaging device according to claim 3.
The correction unit includes a plurality of different exposure conditions when at least one of the imaging signal at the first position and the imaging signal at the second position of the image captured by the imaging unit is not within the allowable range. An image pickup apparatus that picks up an image by the image pickup unit and corrects the image pickup signal based on the plurality of images. The imaging apparatus according to claim 4,
The correction unit corrects a plurality of images obtained at a plurality of different exposure times. In the imaging device according to any one of claims 1 to 5,
The said correction | amendment part correct | amends the dynamic range of the said imaging signal obtained by the said imaging part, The imaging device characterized by the above-mentioned. In the imaging device according to any one of claims 1 to 5,
The setting unit sets a target value of the imaging signal related to a third position that is a halftone in the image. The imaging apparatus according to claim 7,
The image pickup apparatus, wherein the correction unit corrects a dynamic range and gradation characteristics in the image pickup unit. A display procedure for displaying an image based on the image signal on the display unit;
A setting procedure for setting a target value of the image signal at the position in association with a specific position in the image displayed on the display unit;
An image processing program comprising: a correction procedure for correcting the image signal with reference to the target value set in the setting procedure.

Images