JP2011239267A - Imaging apparatus and image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus and an image processing apparatus that produce an image depicted gently as a whole while allowing a main subject to be depicted in a strong contrast to its surroundings.SOLUTION: An imaging apparatus and an image processing apparatus comprise: region-information acquisition means acquiring region information of at least one specific region in image data; distance-information-table calculation means, for each pixel, calculating distance information from the at least one specific region based on the region information; filter-coefficient-table calculation means calculating a filter coefficient applied on each pixel based on the distance information; and filtering means filtering based on the filter coefficients. The filter-coefficient-table calculation means calculates higher LPF coefficients as the filter coefficients for pixels having longer distance from the specific region, based on the distance information. If there are multiple specific regions, the distance-information-table calculation means acquires respective distances from the multiple specific regions, from which the shortest distance is selected as the respective distance information for respective pixels.

Description

  The present invention relates to an imaging apparatus and an image processing apparatus that can obtain an image as if a special lens was used.

Generally, when an artistic photograph, for example, a photograph that can be photographed using a soft focus lens or a tilt shift lens is to be photographed, an expensive lens suitable for the photograph must be prepared.
Therefore, a technique for adding an effect similar to the above-described lens to image data at low cost and easily by digital processing is already known.

  For example, in Patent Document 1, when changing the depth of field of an image by image processing, a desired depth of field is specified by the user, and blurring of the subject is emphasized according to the specified depth of field. Is disclosed.

  However, the conventional image processing (digital soft focus processing) as in Patent Document 1 has a problem that a uniform blur effect is applied to the entire image, so that an image without a blurred core is captured as a whole. . Furthermore, the configuration described in Patent Document 1 has a problem that a blur effect cannot be obtained for a plurality of subjects.

  The present invention has been made in view of the above-described problems in the prior art, and while adding a desired degree of core to one or more main subjects, a relatively strong blurring effect is added to the periphery thereof. Thus, an object of the present invention is to provide an imaging apparatus and an image processing apparatus capable of creating an image with a soft depiction as a whole while enabling an image with a main subject to be emphasized by comparing it with its surroundings.

In order to solve the above problems, an imaging apparatus and an image processing apparatus according to the present invention specifically have technical features described in the following (1) to (11).
(1): An image processing apparatus that performs image processing on input image data, and includes region information acquisition means for acquiring region information of one or more specific regions in the image data, and each pixel in the pixel data The distance information table calculating means for calculating the distance information from the single or plural specific areas to the pixel based on the area information, and the filter coefficient used for the filter processing applied to each pixel in the pixel data, A filter coefficient table calculating means for calculating based on the distance information; and a filter processing means for applying a filter process based on the filter coefficient to each pixel in the pixel data, wherein the filter coefficient table calculating means has the image data For each pixel in, based on the distance information, The distance information table calculation is performed by calculating a low-pass filter coefficient that is stronger as a pixel is larger as the filter coefficient and a weak low-pass filter coefficient or a weak high-pass filter coefficient is calculated as the filter coefficient for the pixels included in the specific region. The means acquires the distance from each of the plurality of specific areas for each pixel in the pixel data when there are a plurality of the specific areas, and is determined to be the closest among the acquired distances An image processing apparatus is characterized in that a distance from a specific area is selected as distance information.

(2) The image processing apparatus according to (1), wherein the area information includes a position, a shape, or a size of the specific area or areas.

(3): The image according to (1) or (2), further including an area operation unit that allows a user to input designation of the specific area or areas and control of the area information. It is a processing device.

(4) The image processing apparatus according to (3), wherein the shape of the specific region includes a circle, an ellipse, or a rectangle.

(5) The image processing apparatus according to (4), wherein the shape of the specific area is a rectangle, and includes both ends of the image data.

(6): It has face detection means for performing face detection in the image data and acquiring face detection information including at least one of the position and size of the face, and the area information acquisition means The image processing apparatus according to (1) or (2), wherein the image processing apparatus is acquired as region information.

(7): The filter coefficient table calculating unit calculates the same low-pass filter coefficient as the filter coefficient for the entire image data when no face is detected from the image data by the face detecting unit. The image processing apparatus according to (6).

(8): When a plurality of faces are detected from the image data by the face detection unit, the filter coefficient table calculation unit assigns priorities based on face detection evaluation values for all detected faces, and The image processing apparatus according to (6) or (7), wherein the filter coefficient is calculated so that the low-pass filter coefficient becomes weaker in descending order of priority.

(9) The image processing apparatus according to (8), wherein the face detection evaluation value includes an AF evaluation value or size of the detected face or a position where the face is detected.

(10) The method according to any one of (1) to (9), further including a filter processing application selection unit that allows a user to select whether or not to apply the filter processing by the filter processing unit. An image processing apparatus.

(11): An imaging apparatus comprising the image processing apparatus according to any one of (1) to (10) above.

  According to the present invention, an image pickup apparatus and an image processing apparatus capable of obtaining an image of a depiction using a special lens by blurring image data by digital image processing and making one or a plurality of main subjects stand out from the background. Can be provided.

It is explanatory drawing which shows the digital still camera as one Embodiment of the imaging device which concerns on this invention, (a) is a front view, (b) is a top view, (c) is a rear view. It is a block diagram which shows the outline | summary of the system configuration | structure of the digital still camera of FIG. It is a block diagram which shows schematic structure of the image process part used by 1st Embodiment of the filter process in the imaging device which concerns on this invention. It is a flowchart which shows the processing flow of 1st Embodiment of the filter process in the imaging device which concerns on this invention. It is the schematic which shows an example of the filter process in case the specific area designated in 1st Embodiment is single. It is the schematic which shows an example of the filter process in case the specific area designated in 1st Embodiment is multiple (two). It is a block diagram which shows schematic structure of the image process part used by 2nd Embodiment of the filter process in the imaging device which concerns on this invention. It is a flowchart which shows the processing flow of 2nd Embodiment of the filter process in the imaging device which concerns on this invention. It is the schematic which shows an example of the filter process in case the specific area designated in 3rd Embodiment is a rectangle.

  An image processing apparatus and an imaging apparatus according to the present invention each perform image processing on input image data, acquire area information of one or more specific areas in the image data, and each of the pixel data A distance information table calculation unit that calculates distance information from the specific region or pixels to the pixel for the pixel based on the region information, and a filter coefficient used for a filter process applied to each pixel in the pixel data. Filter coefficient table calculating means for calculating based on the distance information; and filter processing means for applying filter processing based on the filter coefficient to each pixel in the pixel data, wherein the filter coefficient table calculating means For each pixel in the image data, the identification is performed based on the distance information. A pixel having a larger distance from the area calculates a stronger low-pass filter coefficient as the filter coefficient, and calculates a weak low-pass filter coefficient or a weak high-pass filter coefficient as the filter coefficient for the pixels included in the specific area, and the distance When there are a plurality of specific areas, the information table calculation means acquires the distance from each of the plurality of specific areas for each pixel in the pixel data, and the closest distance among the acquired distances The distance from the determined specific area is selected as distance information.

Next, the image processing apparatus and the imaging apparatus according to the present invention will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

<< One Embodiment of Imaging Device >>
First, prior to describing filter processing, processing associated with the filtering processing, and configuration for executing the filtering processing in the present invention, a configuration of a digital still camera as an embodiment of an imaging apparatus according to the present invention will be described below. This will be described in detail with reference to the drawings.

<Digital still camera>
FIG. 1 is an explanatory view showing a digital still camera (hereinafter referred to as “digital camera 1”) as an embodiment of an imaging apparatus according to the present invention, (a) is a front view, and (b) is a front view. It is a top view, (c) is a rear view. FIG. 2 is a block diagram showing an outline of the system configuration of the digital camera 1 of FIG.

(Appearance structure of digital camera)
In the digital camera 1 of the present embodiment, as shown in FIG. 1, a release button (shutter button) 2, a power button 3, and a shooting / playback switching dial 4 are provided on the upper surface side, and on the front (front) side, A lens barrel unit 6 having a photographing lens system 5, a strobe light emitting unit (flash) 7, and an optical viewfinder 8 are provided.

  In the digital camera 1, on the rear side, a liquid crystal monitor (LCD) 9, an eyepiece 8a of the optical viewfinder 8, a wide-angle zoom (W) switch 10, a telephoto zoom (T) switch 11, a menu (MENU) A button 12, a confirmation button (OK button) 13, and the like are provided. Inside the side surface of the digital camera 1 is provided a memory card storage unit 15 for storing a memory card 14 (see FIG. 2) for storing captured image data. Note that the appearance of the imaging device according to the present invention is not necessarily limited to the present embodiment, and may have another appearance.

(Digital camera system configuration)
As shown in FIG. 2, the digital camera 1 includes a CCD (charge coupled device) 20 and a CCD 20 as a solid-state imaging device on which a subject image incident through a photographing lens system 5 of the lens barrel unit 6 forms an image on a light receiving surface. An analog front end unit 21 (hereinafter referred to as “AFE unit 21”) that processes the output electrical signal (analog RGB image signal) into a digital signal, a signal processing unit 22 that processes the digital signal output from the AFE unit 21, An SDRAM 23 that temporarily stores data, a ROM 24 that stores a control program, a motor driver 25 that drives the lens barrel unit 6, and a memory that can store and read data appropriately by a control unit 28 described later. A RAM 44 and the like are provided.

  The taking lens system 5 includes a zoom lens, a focus lens, and the like. The lens barrel unit 6 includes a photographic lens system 5, an aperture unit 26, and a mechanical shutter unit 27. The drive units of the photographic lens system 5, the aperture unit 26, and the mechanical shutter unit 27 are driven by a motor driver 25. . The motor driver 25 is driven and controlled by a drive signal from a control unit (CPU) 28 of the signal processing unit 22.

  The CCD 20 is a solid-state imaging device that converts a formed subject image into an electrical signal (image data, image signal) and outputs the electrical signal. The CCD 20 has an entire light receiving surface divided into grid-like areas called pixels (hereinafter also referred to as pixels 20a), and converts image data composed of pixel data, which is digital data, into electrical signals. Output as. In the CCD 20, color filters (RGB, CYM, etc.) are provided in each divided area (pixel) so as to form a Bayer array. In this embodiment, an RGB primary color filter (hereinafter referred to as “RGB”) having a Bayer array is provided. Filter "). Therefore, the CCD 20 outputs an electrical signal (analog RGB image signal) corresponding to the three primary colors of RGB from each pixel 20a. The CCD 20 can also be configured with a CMOS image sensor or the like as a solid-state image sensor.

  The AFE unit 21 is sampled by a TG (timing signal generating unit) 30 that drives the CCD 20, a CDS (correlated double sampling unit) 31 that samples an electrical signal (analog RGB image signal) output from the CCD 20, and the CDS 31. An AGC (analog gain control unit) 32 that adjusts the gain of the signal, and an A / D conversion unit 33 that converts the signal gain-adjusted by the AGC 32 into a digital signal (hereinafter referred to as “RAW-RGB data”).

  The signal processing unit 22 includes a CCD interface (hereinafter referred to as “CCD I / F”) 34, a memory controller 35, a YUV conversion unit 36, a resizing processing unit 37, a display output control unit 38, and a data compression unit 39. , A media interface (hereinafter referred to as “media I / F”) 40, an image processing unit 42, and a control unit (CPU) 28.

  The CCD I / F 34 outputs a screen horizontal synchronization signal (HD) and a screen vertical synchronization signal (VD) to the TG 30 of the AFE unit 21, and from the A / D conversion unit 33 of the AFE unit 21 according to these synchronization signals. The output RAW-RGB data is captured. The memory controller 35 controls the SDRAM 23. The YUV converter 36 converts the RAW-RGB data captured by the CCD I / F 34 into image data in YUV format that can be displayed and recorded. The resizing processing unit 37 changes the image size according to the size of image data to be displayed or recorded. The display output control unit 38 controls display output of image data. The data compression unit 39 converts the data so that the image data is recorded in the JPEG format or the like. The media I / F 40 writes image data to the memory card 14 or reads image data written to the memory card 14. The image processing unit 42 performs a filter process and a process associated with the filter process in a process in which the image data (image signal) acquired by the CCD 20 propagates in the signal processing unit 22. This filtering process and the process accompanying the filtering process will be described in detail later. The control unit 28 performs system control and the like of the entire digital camera 1 based on a control program stored in the ROM 24 in accordance with operation input information from the operation unit 41.

  The operation unit 41 includes a release button 2, a power button 3, a shooting / playback switching dial 4, a wide-angle zoom switch 10, a telephoto zoom switch 11, a menu button 12, and a confirmation button 13 provided on the external surface of the digital camera 1. Etc. (see FIG. 1), and a predetermined operation instruction signal corresponding to the operation of the photographer is input to the control unit 28.

  The SDRAM 23 stores RAW-RGB data captured by the CCD I / F 34 and also stores YUV data (YUV format image data) converted by the YUV conversion unit 36. In addition, the data compression unit 39 The image data such as JPEG formation that has been subjected to compression processing is saved. The YUV data is the luminance data (Y), the color difference (U) that is the difference between the luminance data and the blue (B) component data, and the color difference (V) that is the difference between the luminance data and the red (R) component data. ) Information to express color.

(Digital camera monitoring and still image shooting)
Next, the monitoring operation and still image shooting operation of the digital camera 1 will be described. In the still image shooting mode, the digital camera 1 performs a still image shooting operation while executing a monitoring operation as described below.

  First, when the photographer turns on the power button 3 and sets the photographing / playback switching dial 4 to the photographing mode, the digital camera 1 is activated in the recording mode. When the control unit 28 detects that the power button 3 is turned on and the photographing / playback switching dial 4 is set to the photographing mode, the control unit 28 outputs a control signal to the motor driver 25 to allow the lens barrel unit 6 to be photographed. And the CCD 20, the AFE unit 21, the signal processing unit 22, the SDRAM 23, the ROM 24, the liquid crystal monitor 9 and the like are activated.

  Then, the photographing lens system 5 of the lens barrel unit 6 is directed toward the subject, so that the subject image incident through the photographing lens system 5 is formed on the light receiving surface of each pixel of the CCD 20. Next, an electrical signal (analog RGB image signal) corresponding to the subject image output from the CCD 20 is input to the A / D conversion unit 33 via the CDS 31 and the AGC 32, and 12 bits (bits) by the A / D conversion unit 33. To RAW-RGB data.

  This RAW-RGB data is taken into the CCD I / F 34 of the signal processing unit 22 and stored in the SDRAM 23 via the memory controller 35. The RAW-RGB data read from the SDRAM 23 is converted into YUV data (YUV signal) by the YUV conversion unit 36 and then stored as YUV data in the SDRAM 23 via the memory controller 35.

  The YUV data read from the SDRAM 23 via the memory controller 35 is sent to the liquid crystal monitor (LCD) 9 via the display output control unit 38, and the photographed image is displayed on the liquid crystal monitor (LCD) 9. At the time of monitoring in which a captured image is displayed on the liquid crystal monitor (LCD) 9, one frame is read out in a time of 1/30 seconds by the pixel number thinning process by the CCD I / F 34. For this reason, the AFE unit 21 and the signal processing unit 22 function as an image generation unit under the control of the control unit 28.

  In this monitoring operation, the photographed image is only displayed on the liquid crystal monitor (LCD) 9 functioning as an electronic viewfinder, and the release button 2 is not yet pressed (including half-pressed).

  By displaying the photographed image on the liquid crystal monitor (LCD) 9, the photographer can check the composition for photographing the still image. Note that the digital camera 1 can output a TV video signal from the display output control unit 38 and display a photographed image on an external TV (television) (not shown) via a video cable.

  Shooting is performed by pressing the shutter button 2. When it is necessary to adjust the angle of view prior to shooting, the photographer operates the wide-angle zoom switch 10 and the telephoto zoom switch 11 to zoom the zoom lens included in the shooting lens system 5 and adjust the angle of view.

  When the shutter button 2 is half-pressed, the CPU 28 performs AE / AF processing, determines the aperture value and the shutter speed, and controls the aperture unit 26 and the mechanical shutter unit 27 according to this to obtain an appropriate exposure amount.

  Thereafter, when the photographer presses down the shutter button 2, the CPU 28 starts photographing and recording processing. In other words, the CPU 28 exposes the CCD 20 by controlling the aperture unit 26 and the mechanical shutter unit 27 to control the exposure time of the CCD 20.

  The image signal output from the CCD 20 is stored in the SDRAM 23 as YUV data by the same processing as in the monitoring operation described above. (At this time, the image processing unit 42 performs a filtering process and a process associated with the filtering process in the process in which the image data acquired by the CCD 20 propagates in the signal processing unit 22. Details thereof will be described later. .)

The YUV data stored in the SDRAM 23 is compressed by the data compression unit 39 in accordance with a predetermined compression format (for example, JPEG format), then stored in the SDRAM 23 again to be an image file of a predetermined image recording format, and then the memory The image is recorded on the card 14 and the imaging operation is terminated.
The image recorded on the memory card 14 as described above can be reproduced and displayed on the LCD 9.

  Next, the filtering process, the process associated with the filtering process, and the configuration for executing the filtering process in the present invention will be described in detail below with specific examples.

<< First Embodiment of Filter Processing >>
A first embodiment of filter processing in an imaging apparatus according to the present invention will be described.
First, an outline of the soft focus lens and a method for realizing the soft focus lens by digital processing (image processing) will be described.
In the case of a normal lens, light from the subject is collected at one point by the lens.
On the other hand, in the case of a soft focus lens, light is dispersed (aberration) while avoiding collecting light at one point. By doing this, it is possible to shoot a soft depiction of a foggy image, such as light in a bright portion.

  In order to realize the effect of the soft focus lens by image processing, it is conceivable to average and blur image data by applying a low-pass filter. However, if the low-pass filter is used to obtain a certain degree of blurring effect on the entire image, the image will have no core.

Therefore, in normal shooting, there should be a main subject (what you want to shoot), so the minimum area including the main subject is blurred with a weak low-pass filter that leaves a core, and the periphery is a stronger low-pass filter. Blur.
At this time, if the blur method is suddenly changed in a specific region and its surroundings, an unnatural edge may be generated at the boundary that changes the blur method. As a countermeasure, by setting the coefficient of the low-pass filter so that the pixel is farther away from the specific region, the blur is natural.

As described above, in the present embodiment, the entire image is blurred using the low-pass filter, and a soft depiction image as if taken using the soft focus lens is generated, while the blurring effect of the local region including the main subject is generated. Weaken. By doing so, the main subject is emphasized in the image due to the difference in blurring between the main subject and its surroundings, and an image can be taken while leaving a certain amount of core in the main subject.
The above is the outline of the soft focus lens and the principle of the digital processing (image processing) of the soft focus lens.

Next, the configuration of the image processing unit in the present embodiment will be described in more detail.
FIG. 3 is a block diagram showing a schematic configuration of an image processing unit used in the first embodiment of the filter processing in the imaging apparatus according to the present invention. Note that the image processing unit that constitutes a part of the imaging apparatus may be used independently as an image processing apparatus, and the same applies to the second and third embodiments described below.
As shown in FIG. 3, the image data input to the image processing unit is supplied to the distance information table calculating unit after the region information is acquired by the region information acquiring unit. The distance information table calculation means acquires distance information of each pixel, and the filter coefficient is calculated by the next filter coefficient table calculation means based on the distance information. Thereafter, a filtering process is performed on each pixel, and post-filtering image data subjected to a desired filtering process is obtained. In the present embodiment, a command is input by the user operating the operation unit, and the position, shape, and size of the specific area are changed to a desired one by the area operation unit.

Furthermore, the processing flow for realizing the soft filter effect will be specifically described.
FIG. 4 is a flowchart showing a processing flow of the first embodiment of the filter processing in the imaging apparatus according to the present invention.
Here, in the present embodiment, it is assumed that the user can specify a region (specific region) in which the blurring effect is weakened as described above. It should be noted that the present invention is not limited to such a mode, that is, the specific region includes both a region specified by the user or a region automatically specified (depending on a desired setting).

-Area designation First, a shooting mode (soft focus mode) that provides the soft focus effect proposed in the present embodiment is selected. Then, a circular (including ellipse) or rectangular frame is displayed in the monitoring image displayed on the LCD 9.
This frame can be moved up and down and left and right (designated position) by operating a button (operation unit 41; area operation means) of the camera. Further, the shape of the frame can be switched by button operation (circle to rectangle, rectangle to circle, etc.) and the size of the frame can be controlled. That is, with the digital camera facing the subject, the user operates the digital camera so that this frame surrounds the main subject (region operation means).
One or more specific areas can be designated, and the shape, frame size, and position can be individually changed. When the shape, size and position of the frame are determined, the release button 2 is pressed to take a picture.

Shooting / Acquisition of Image Data / Acquisition of Area Information When shooting is started, area information including a specified position, size, and shape is acquired for each of a plurality of specific areas specified by the user (area information acquisition means).

-Distance information table calculation Next, the distance from a specific area is calculated about all the pixels of the input image data, referring area information. When a plurality of specific areas are designated, the distance from each pixel (target pixel) is calculated for all the specific areas (distance information table calculating means). Of the distances calculated for all the specific areas with respect to the target pixel, the distance from the specific area closest to the target pixel is determined as “distance from the specific area” in the target pixel and is selected as distance information. . However, if the distance data is held for each of all the pixels, the memory for storing the information becomes very large. Therefore, for example, the distance that maximizes the distance from the specific region may be normalized as 255, and the distance information may be used as an index of 0 to 255.

Filter coefficient table calculation When the distance information is calculated, a filter coefficient to be applied to each pixel is calculated based on the distance information (filter coefficient table calculating means). In the present embodiment, a low-pass filter coefficient is calculated as a filter coefficient, and a filter coefficient is set such that the effect of the low-pass filter becomes stronger as the distance from the specific region increases. In the present embodiment, weak (low-pass) filter coefficients are set for the pixels included in the specific region.

-Filter processing The above processing steps are performed, and a low-pass filter process is performed on the image data by referring to a distance information table composed of finally calculated distance information and a (low-pass) filter coefficient table (filter processing means).

FIG. 5 is a schematic diagram illustrating an example of a filtering process in the case where a single specific region is designated in the first embodiment.
In the example illustrated in FIG. 5, the filtering process is performed so that the blurring effect is weak in the specific region located in the center, and the blurring effect becomes strong as the distance from the specific region increases (as the four sides approach). Is calculated).

Furthermore, FIG. 6 is a schematic diagram illustrating an example of a filtering process when there are a plurality (two) of specific areas designated in the first embodiment.
In the example illustrated in FIG. 6, the blurring effect is weak in the two specific areas located at the lower left (specific area 1) and the upper right (specific area 2) in FIG. 6, and the blurring effect increases as the distance from the specific area increases. Filter processing is performed to increase the intensity (low pass filter coefficients are calculated).
Here, calculation of the distance (distance information) from two specific regions will be described using a specific example shown in FIG. The distance from the target pixel shown in FIG. 6 is calculated by calculating the distance A from the specific area 1 and the distance B from the specific distance 2, and then determining the magnitude relationship between the distance A and the distance B. The distance information at the target pixel is used. Even if the specific area is 3 or more, the same determination is made, and any one having the longest distance is set as the distance information.
Then, distance information for all the pixels in the image data is acquired, and filter processing is performed so that the blurring effect becomes stronger as the distance from the specific region increases (low pass filter coefficient is calculated).

  In the first embodiment of the filter processing in the imaging apparatus according to the present invention described above, specifically, in the soft focus processing by digital processing, one or a plurality of position areas of the main subject are designated to the user before shooting. When shooting, refer to it and strengthen the low-pass filter coefficient of the pixel at a position away from the specified specific area, while the specified specific area is low-pass filter processed on the entire image with a low-pass filter coefficient weaker than its surroundings. By performing the above, a soft depiction using a soft focus lens is applied to the entire image, and the main subject can stand out from the periphery.

  In this way, while blurring the entire image using a low-pass filter, or creating a soft depiction of an image taken with a soft focus lens, each local area including multiple main subjects is blurred. By reducing the effect, a plurality of main subjects are emphasized in the image due to differences in blurring between the main subject and its surroundings, and an image with a certain amount of core remaining in the main subject can be taken.

<< Second Embodiment of Filter Processing >>
In the first embodiment, the user can designate a specific area, but there are also users who feel that the operation of such specific area designation (area setting) is troublesome. The soft focus lens is often used for a portrait photograph of a woman because it draws a soft impression and makes the wrinkles and spots of the face inconspicuous.
In this embodiment, therefore, a soft focus that automatically detects a person's face from the subject and easily sets the person as the main subject (specific area) without requiring complicated area setting based on the detection data. A method for taking an image will be described.

First, the configuration of the image processing unit in the present embodiment will be described in more detail.
FIG. 7 is a block diagram showing a schematic configuration of an image processing unit used in the second embodiment of the filter processing in the imaging apparatus according to the present invention.
As shown in FIG. 7, the image data input to the image processing unit is subjected to face detection by face detection means, and face detection information is obtained. This face detection information is acquired as region information by the region information acquisition unit, and then provided to the distance information table calculation unit. The distance information table calculation means acquires distance information of each pixel, and the filter coefficient is calculated by the next filter coefficient table calculation means based on the distance information. Thereafter, a filtering process is performed on each pixel, and post-filtering image data subjected to a desired filtering process is obtained.
In this embodiment, the user does not designate a specific area, and face detection (specific area designation) is automatically performed. Note that even if the command is input by the user operating the operation unit, the position, shape, and size of the specific area, which is the acquired face detection information, are changed to a desired one by the area operation means. I do not care.

Next, the processing flow for realizing the face detection and the soft filter effect will be specifically described.
FIG. 8 is a flowchart showing a processing flow of the second embodiment of the filter processing in the imaging apparatus according to the present invention.

Photographing / image data acquisition / face detection / face detection data acquisition A digital camera having a face detection function is used to photograph a person as a subject, and face detection is performed from the generated image data using a face detection function (face detection means) ). The face detection method will be described later.

-Region information acquisition First, consider the case where the face detection function detects a single face. (In FIG. 8, when there is a face in the image: YES, the number of detected faces = 1: YES.)
From the result of face detection (face detection information), the position and size of the face on the image data are acquired. As the specific area, since the face is an ellipse, the shape of the specific area is an ellipse, and the size of the specific area is a size that includes the size of the face. Further, the result of face detection may be used as the specific area as it is.

Next, consider a case where the face detection function detects a plurality of faces. (In FIG. 8, when there is a face in the image: YES, face detection count = 1: NO.)
For example, when N faces are detected, priorities from the first priority to the Mth priority are assigned to the detected faces. However, M and N are integers, and M ≦ N. The priority of the main subject (face) will be described later.
Thereafter, in the same manner as the calculation of the LPF (low-pass filter) parameter depending on the distance from the specific region presented in the first embodiment, the LPF effect is changed from 1 (high priority) to M (priority). It is only necessary to calculate and set a parameter that becomes stronger as the value becomes lower. Further, when it is desired to emphasize only the face of a specific person, it is possible to perform control such that the LPF parameter is weakened only for the first main subject.

  In FIG. 8, if there is a face in the image: NO, the region information acquisition and the distance information table calculation are not performed, there is no main subject (specific region), and the filter is applied to uniformly blur the entire screen. Only coefficient table calculation and filter processing are performed. Specifically, the same low-pass filter coefficient (filter coefficient) is calculated for the entire image data, and filter processing is performed using this low-pass filter coefficient.

Distance information table calculation / filter coefficient table calculation / filter processing The distance information table calculation, the filter coefficient table calculation, and the filter processing are the same as those in the first embodiment, and a description thereof will be omitted.

<Description of face detection method>
As a method for detecting a human image (face) from a subject image, the following methods (A) to (C) are known, and in this embodiment, the following (A) to (C) are used. Any one of the methods shown in FIG.
(A) Television Society Journal Vol. 49, no. 6, pp. No. 787-797 (1995) “Proposal of a modified HSV color system effective for face area extraction” is a method of extracting a face area by converting a color image into a mosaic image and paying attention to a skin color area.
(B) IEICE Journal Vol. 74-D-II, no. 11, pp. 1625-1627 (1991) “A method for extracting a face region from a still gray scene image”, the geometrical structure of each part constituting the head of a front human figure such as hair, eyes and mouth. Of extracting the head region of a frontal person using various shape features.
(C) As shown in “Video phone face area detection and its effect” in Image Lab 1991-11 (1991), in the case of a moving image, a contour edge of a human image generated by a subtle movement of a person between frames To extract a frontal portrait using GIS.

  Note that the processing flow shown in FIG. 8 discloses a configuration in which face detection is performed on image data acquired by shooting, but the present invention is not limited to this, and at the same time or Alternatively, the face may be detected when the angle of view (framing) before photographing is determined.

<Priority of main subject>
For example, the following priorities (1) to (3) are considered as methods of assigning priorities to main subjects. It should be noted that priority is determined based on the face size, AF evaluation value, and position (which will be referred to as face detection evaluation values) shown below, and the low-pass filter coefficient is decreased in order from the higher priority. Calculate the coefficient.
(1) Detected face size The larger the detected face size, the higher the priority.
(2) AF evaluation value A face with AF is determined from the AF evaluation value of the detected face, and a priority is assigned based on the height of the AF evaluation value.
(3) Position Since it is considered that the main subject is usually located at the center of the image, the priority is set higher as the position from the center of the image is closer.

<< Third embodiment of filter processing >>
Here, a method for realizing the miniature effect that can be obtained by the tilt shift lens by digital processing will be described.
First, the tilt shift lens and the miniature effect will be described.
The tilt shift lens is a lens having a mechanism for tilting the lens, and the depth of field can be artificially reduced by tilting the lens. For example, when the lens is tilted back and forth, the upper and lower depths of field become shallower, and when the lens is tilted left and right, the left and right depths of field become shallower. Using this mechanism, it is usually used to focus on both near and far subjects, but the depth of the subject is controlled to create a focused area and a blurred area. There is a technique (called reverse tilt) that makes a real scene look as if a miniature was photographed by losing reality. The tilt shift lens is also a lens that is preferably used by those who want to take artistic photographs for such purposes.

  However, the tilt shift lens is generally intended for special photography, and is not expensive and can be purchased easily although it lacks versatility. In order to solve this problem, a method for realizing reverse tilt in digital processing will be described.

  In the first embodiment and the second embodiment described above, a low-pass filter coefficient that is weaker than that of the surrounding area is applied to the specific area. However, in this embodiment, a low-pass filter coefficient is applied to the specific area. The filtering process may not be performed, or the high-pass filter coefficient may be applied rather weakly.

FIG. 9 is a schematic diagram illustrating an example of filter processing when the specific area designated in the third embodiment is a rectangle.
The specific area in the present embodiment is a rectangle, and includes an area including both ends of the image. In the same way as before, the parameter is strongly set according to the distance from the specific area.
That is, as shown in FIG. 9, since the blurred range is the top and bottom or left and right regions of the image, the effect of the tilt shift lens can be obtained according to this embodiment. Alternatively, the blurred range may be an oblique (not shown) region located between the top and bottom and the left and right shown in FIG.

  If a miniature-like image is expected, a more miniature-like image can be obtained by adjusting the saturation and contrast (generally increasing the saturation and contrast).

  The third embodiment described above is different in that the shape of the specific area in the first embodiment is rectangular and includes both ends of the image data. In common. For this reason, the description overlapping with the first embodiment is omitted.

<< Other Embodiments of Filter Processing >>
In addition to the first to third embodiments described above, a configuration may further include a filter processing application selection unit that allows the user to select whether or not to apply the filter processing by the filter processing unit.

DESCRIPTION OF SYMBOLS 1 Digital still camera 21 Analog front end part 22 Signal processing part 23 SDRAM
24 ROM
28 Control Unit 42 Image Processing Unit 44 RAM

JP 2009-284056 A

Claims (11)

An image processing apparatus that performs image processing on input image data,
Area information acquisition means for acquiring area information of one or more specific areas in the image data;
For each pixel in the pixel data, distance information table calculating means for calculating distance information from the specific region or pixels to the pixel based on the region information;
A filter coefficient table calculating means for calculating a filter coefficient used for filter processing applied to each pixel in the pixel data based on the distance information;
Filter processing means for applying a filtering process based on the filter coefficient to each pixel in the pixel data,
The filter coefficient table calculating unit calculates, as the filter coefficient, a low-pass filter coefficient that is stronger for each pixel in the image data, based on the distance information, for a pixel having a greater distance from the specific area. For the pixels included in the region, a weak low pass filter coefficient or a weak high pass filter coefficient is calculated as the filter coefficient,
When there are a plurality of the specific areas, the distance information table calculation unit acquires the distance from each of the plurality of specific areas for each pixel in the pixel data, and the distance is the longest among the acquired distances. An image processing apparatus, wherein a distance from a specific area determined to be close is selected as distance information.   The image processing apparatus according to claim 1, wherein the area information includes a position, a shape, or a size of the one or more specific areas.   The image processing apparatus according to claim 1, further comprising an area operation unit that allows a user to input designation of the specific area or areas and control of the area information. The image processing apparatus according to claim 3, wherein the shape of the specific region includes a circle, an ellipse, or a rectangle.   The image processing apparatus according to claim 4, wherein the shape of the specific area is a rectangle and includes both ends of the image data. Face detection means for performing face detection in the image data and acquiring face detection information including at least one of the position and size of the face;
The image processing apparatus according to claim 1, wherein the area information acquisition unit acquires the face detection information as the area information. The filter coefficient table calculation unit calculates the same low-pass filter coefficient as the filter coefficient for the entire image data when a face is not detected from the image data by the face detection unit. 6. The image processing apparatus according to 6. The filter coefficient table calculation unit assigns priorities based on face detection evaluation values for all detected faces when the face detection unit detects a plurality of faces from the image data, and the priority is high. The image processing apparatus according to claim 6, wherein the filter coefficient is calculated so that the low-pass filter coefficient becomes weaker in order from one side. The image processing apparatus according to claim 8, wherein the face detection evaluation value includes an AF evaluation value or size of a detected face, or a position where a face is detected. The image processing apparatus according to claim 1, further comprising: a filter processing application selection unit that allows a user to select whether or not to apply the filter processing by the filter processing unit.   An imaging apparatus comprising the image processing apparatus according to claim 1.