JP2010093374A - Method of checking photographing environment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of checking photographing environments for checking a photographing environment, where a photographed image suitable for replacement of backgrounds can be obtained. <P>SOLUTION: The method includes: a photographing process for obtaining the photographed image by irradiating a known reference subject for checking photographing environments with light from a prescribed background surface, and by photographing the reference subject from a side opposite to the background surface while sandwiching the reference subject; a first brightness analysis process for analysis of brightness in a known subject region in which the reference subject has been taken for the photographed image obtained in the photographing process; a second brightness analysis process for analysis of brightness in a known background region in which the background of the reference subject has been taken for the photographed image obtained by the photographing process; and a decision process for determining whether brightness in a background region is larger than that of a subject region and the difference between the brightness in the background region and that of the subject region exceeds a prescribed degree. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photographing environment confirmation method for confirming whether or not an environment capable of photographing a photographed image suitable for background replacement when a background replacement image is created by replacing a background in a photographed image with another background.

  Conventionally, photography using a background curtain has been performed in a photo studio or the like. However, in such shooting, a large backdrop is used to create a sufficient background, and a large shooting space is required. In addition, it takes time to replace the background curtain, and as a result, the photographing cost increases.

  Therefore, there is a demand for the development of a compact photographing system that does not require a large background screen and a wide photographing space as in the past so that photographing can be performed more easily. In such a small photographing system, instead of the background curtain as described above, photographing is performed in front of some temporary background, and the background in the photographed image is set by the customer with respect to the photographed image obtained by photographing. A background replacement process for replacing the desired background is performed.

  As an example of the technology related to such background replacement processing, for example, a background panel painted in blue or the like is placed behind the subject to perform shooting, and in the captured image obtained by the shooting, the color of the background panel A process called chroma key processing is known in which the same color part and the different color part are distinguished from each other as the background and the subject in the photographed image, and the part distinguished from the background in the photographed image is replaced with a desired background. (For example, refer to Patent Document 1).

  In addition, for example, in a place where the back of the subject is open, such as outdoors, shooting is performed under two illumination conditions, that is, a state where the illumination directed to the subject is turned on and a state where the illumination is turned off. When a captured image is acquired and the two captured images are compared, a portion with different brightness and a portion with the same brightness are distinguished from the subject in the captured image and the background, respectively, and distinguished from the background in the captured image. There is also known a technique of replacing the formed portion with a desired background (see, for example, Patent Document 2).

  As described above, in order to satisfactorily replace the background in the photographed image with the desired background, it is necessary to distinguish the subject and the background in the photographed image obtained by photographing well. However, in the technique disclosed in Patent Document 1, if a subject in a captured image has a spot of the same color as that of the background panel, the spot is mistaken as a background, and a part of the subject has the above desired background. There is a risk that an unnatural background-replaced image replaced with will be created. On the other hand, in the technique of Patent Document 2 described above, since the subject and the background are distinguished based on the luminance in the captured image, even if the subject has a spot of the same color as the background, that spot is the background. The risk of being misidentified is eliminated. However, it is inevitable that a photographing device such as a background panel is placed behind a subject in a small photographing system that can be easily photographed in a photo studio or the like.

For this reason, when the technique of Patent Document 2 is applied to such a small imaging system, the illumination applied to the subject is reflected by these imaging equipment, and the luminance between the two captured images obtained under the two illumination conditions increases. A different part also occurs in the background, and a part of the background is mistakenly recognized as a subject, and an unnatural background replacement image in which a part of the background leaks from the replacement is generated.
JP 2000-224410 A (page 3-10, FIG. 3) Japanese Patent Laid-Open No. 10-210340 (page 2-3, FIG. 1)

  Therefore, the subject and the background are distinguished from each other by a photographed image obtained by photographing in a backlight state illuminated from the opposite side of the photographing apparatus with the subject sandwiched between, and a photographed image having a large brightness difference between the background and the subject. A method for creating a replacement image is conceivable. This method is considered to be more adaptable to a small photographic system than other conventional methods.

  However, even with this method, if the shooting environment is inappropriate and light is strongly reflected on the subject from the surroundings of the shooting system or there is a particularly dark part in the illumination from behind, the subject and background The distinction becomes inaccurate and an unnatural background replacement image is created.

  In view of the circumstances described above, an object of the present invention is to provide a photographing environment confirmation method for confirming whether or not a photographing environment suitable for background replacement is obtained.

The photographing environment confirmation method of the present invention that achieves the above-mentioned object is as follows.
A process of obtaining a photographed image by irradiating a known reference subject for confirming the shooting environment with light from a predetermined background surface, and photographing the reference subject from the opposite side of the reference subject with the background surface; ,
A first brightness analysis process for analyzing the brightness of a known subject area in which the reference subject is captured with respect to a captured image obtained in the shooting process;
A second brightness analysis process for analyzing the brightness of a known background area in which the background of the reference subject is reflected in the captured image obtained in the shooting process;
And determining whether or not the brightness of the background area is brighter than that of the subject area and the difference in brightness exceeds a predetermined level.

  In backlit shooting, the subject will be closer to the shadow side and the background will be closer to the highlight side. The difference in brightness between these subjects and the background is better. Can be done. Therefore, in the shooting environment check method of the present invention, a known reference object for checking the shooting environment is prepared and light is emitted from a predetermined background surface, and this reference surface is sandwiched from the opposite side of the reference object. A photographed image is obtained by photographing the subject, and it is determined whether or not the brightness of the background region exceeds the predetermined level and is brighter than the brightness of the subject region.

  Here, it is preferable that the reference subject has a mirror-like part on at least a part of the surface, and has a transmission part that transmits light from the background surface on at least a part. This is also a preferred embodiment.

  When these are used as reference subjects, if the brightness of the background region exceeds a predetermined level rather than the brightness of the subject region, it is more reliably determined that the captured image is suitable for background replacement. It becomes.

  According to the present invention, it is possible to provide a photographing environment confirmation method for confirming whether or not the photographing environment is suitable for obtaining a photographed image suitable for background replacement.

  Before describing the embodiments of the present invention, the basic content of the background replacement method and the equipment necessary for carrying out the method will be described below.

  FIG. 1 is a diagram showing an outline of a photographing system for creating a background replacement image.

  The photographing system 1 shown in FIG. 1 is a photographing system that is smaller and simpler than the prior art, and shoots a subject and obtains a photographed image, and separates the subject and background in the photographed image. Separately, a personal computer 20 that operates as an example of a background replacement device that replaces a background in a captured image with a desired background to create a background replacement image, a printer 30, and a server 40 are provided. The photographing studio 10 includes a digital camera 11, a flash light emitting device 12, an EL (electroluminescence) panel 130, and a power source 14 for the EL panel.

  The digital camera 11 has a continuous shooting function. When the photographer presses the shutter button once, the digital camera 11 automatically photographs the subject P twice in a short time. A photographed image obtained by each photographing is temporarily stored in a memory in the digital camera 11, but in the photographing system 1, the digital camera 11 is connected to the personal computer 20, and two photographings are performed. When the processing is completed, the captured image obtained by the two capturing operations is immediately sent to the personal computer 20. The digital camera 11 is also connected to the flash light emitting device 12, and the digital camera 11 transmits an instruction signal for instructing the flash light emitting device 12 to emit a flash to the flash light emitting device 12.

The flash light emitting device 12 receives an instruction signal from the digital camera 11 and emits a flash only during the first shooting of the two shootings. Further, the flash light emitted from the flash light emitting device 12 is high-luminance light having a light emission luminance of about 2000 cd / m ² .

  The EL panel 130 includes a housing 131 in which a placement surface 131 a on which the subject P is placed and a surface 131 b behind the subject P are transparent, and a distributed EL element 132 housed in the housing 131. The power source 14 is a power source that applies a driving voltage to the distributed EL element 132.

  The dispersion type EL element 132 is a sheet in which a phosphor powder is dispersed in a binder having a high dielectric constant and is sandwiched between two sheet-shaped electrodes having a flexible plastic substrate. Shaped surface emitting light source. The distributed EL element 132 emits light when an AC voltage is applied from the power source 14 between the two electrodes.

  This distributed EL element 132 is a very thin and light light source having a thickness of several hundreds μm to 1 mm, and can be easily installed in a place where there is no sufficient thickness, such as the inside of the housing 131. In addition, the dispersion-type EL element 132 emits light of a color between blue and green having two or more peaks in the emission wavelength range of 400 nm to 530 nm. The power source 14 can adjust the AC voltage applied to the distributed EL element 132 between 50 Hz to 10 kHz with respect to the frequency and between 40 V to 300 V with respect to the magnitude. The luminance of light emitted from the dispersion type EL element 132 is substantially proportional to the magnitude of the applied AC voltage.

  Here, in the photographing studio 10, photographing by the digital camera 11 is performed in a state where the EL panel 130 is always lit. Further, as described above, the first shooting is performed with the flash light emitting device 12 emitting a flash, and the second shooting is performed with the flash light emitting device 12 turned off. Here, as described above, the brightness of the flash emitted by the flash light emitting device 12 is considerably higher than the brightness when the EL panel 130 is turned on. As a result, in the first shooting, a follow-up image in which the subject P is clearly captured by shooting in a follow-up state in which a flash with a brightness higher than that of the EL panel 130 illuminates the subject P from the digital camera 11 side. To be acquired. In the second shooting performed continuously after the first shooting, the image of the subject P is biased to the shadow side by shooting in a backlight state in which only the light from the EL panel 130 illuminates the subject P from behind. A backlight image in which the image of the background panel 130 is biased toward the highlight side is acquired.

  As described above, the personal computer 20 operates as an example of the background replacement device.

  The personal computer 20 performs a background replacement process of creating a background replacement image based on the above-described two captured images transmitted from the digital camera 11. This background replacement process will be described later.

  This personal computer 20 has a flexible disk (hereinafter referred to as FD) and a CD-ROM loading port in terms of appearance and has a function of accessing the FD and CD-ROM loaded in the loading port. 210, an image display device 220 that displays an image on the display screen 220a in accordance with an instruction from the main device 210, a keyboard 230 that inputs various types of information according to key operations to the main device 210, and an arbitrary on the display screen 220a Is designated, for example, a mouse 240 for inputting an instruction corresponding to an icon or the like displayed at that position, and a small storage medium used for storing a photographed image by a digital camera or the like are loaded. A media drive 250 for accessing storage media is provided.

  The printer 30 prints an image sent from the personal computer 20, and the photographing system 1 plays a role of printing a background replacement image created by the personal computer 20 by the background replacement process.

  The server 40 stores a plurality of types of backgrounds used in the background replacement process executed by the personal computer 20. The background in the server 40 is presented to the customer by being displayed on the display screen 220a. In addition to the background stored in the server 40, the imaging system 1 also provides a background provided via some input storage medium such as the CD-ROM or the small storage medium. It is presented to the customer through 220a. The customer selects a desired background from the backgrounds displayed on the display screen 220a.

  Next, the flow of work executed in the photographing system 1 shown in FIG. 1 will be described. In the following description, the elements shown in FIG. 1 are referred to by using the reference numerals in FIG.

  FIG. 2 is a diagram showing a flow of work executed in the photographing system shown in FIG.

  First, a voltage is applied from the power supply 14 to the distributed EL element 132, and the EL panel 130 is turned on (step S101). Next, when the photographer presses the shutter button of the digital camera 11 after adjusting the focus and exposure, the subject P is photographed twice consecutively. First, in the first shooting, the flash light emitting device 12 emits a flash with a luminance higher than that of the illumination of the EL panel 130 in response to an instruction signal transmitted from the digital camera 11, and the subject P is shot in a forward light state by the flash. (Step S102). Subsequently, the second shooting is performed in a state where the flash light emitting device 12 is turned off, that is, in a backlight state by illumination of only the EL panel 130 (step S103). The two captured images, the follow light image and the backlight image, obtained by the processes in steps S102 and S103, respectively, are temporarily stored in the memory in the digital camera 11.

  The second shooting is performed by the process of step S103, and when the captured image obtained by the shooting is stored in the memory in the digital camera 11, it is obtained by the second shooting and temporarily stored in the memory. The stored two captured images are immediately transferred to the personal computer 20. In response to an operation on the personal computer 20, the background desired by the customer is read from the server 40 or some input storage medium (step S104). Subsequently, a background replacement process to create a background replacement image based on these captured images is executed (step S105). The image data representing the background replacement image created by the background replacement processing is first transferred to the image display device 220, and further to at least one of the printer 30 and the output storage medium desired by the customer. Transferred (step S106). Subsequently, in the image display device 220, the background replacement image is displayed on the display screen 220a based on the transferred image data (step S107), and when the image data is transferred to the printer 30, In the printer 30, the background replacement image is printed based on the image data (step S108).

  Next, the internal configuration of the personal computer 20 will be described.

  FIG. 3 is a hardware configuration diagram of the personal computer shown in FIG.

  As shown in FIG. 3, inside the main body device 210, a CPU 211 that executes various programs, a main memory 212 that is read out by a program stored in the hard disk device 213 and developed for execution by the CPU 211, A hard disk device 213 in which programs and data are stored, an FD 520 are loaded, an FD drive 214 that accesses the loaded FD 520, a CD-ROM drive 215 that accesses a CD-ROM 510, the server 40 and the digital camera 11 in FIG. And an input interface 216 for receiving a replacement background, a photographed image and the like from these devices, and an output interface 217 for connecting the printer 30 of FIG. 1 and outputting the background replacement image and the like. And the various elements shown in Figure 1 Image display device 220, a keyboard 230, a mouse 240 and a media drive 250 for accessing a small storage medium 530 are connected to each other via a bus 260.

  Here, the CD-ROM 510 stores a background replacement program for operating the personal computer 20 as a background replacement device. When the CD-ROM 510 storing the background replacement program is loaded into the CD-ROM drive 215, the background replacement program stored in the CD-ROM 510 is uploaded to the personal computer 20 and written to the hard disk device 213. It is. Thereby, the personal computer 20 operates as a background replacement device.

  Next, the background replacement program will be described.

  FIG. 4 is a conceptual diagram showing a CD-ROM in which a background replacement program is stored.

  A CD-ROM 510 shown in FIG. 4 stores a background replacement program 600 for operating the personal computer shown in FIGS. 1 and 3 as an example of the background replacement device.

  The background replacement program 600 includes an image acquisition unit 610, a replacement processing unit 620, an image data transfer unit 630, an image display unit 640, and a photographing environment determination unit 650.

  Details of each part of the background replacement program 600 will be described together with the operation of each part of an example of the background replacement device. In the following description, the elements shown in FIGS. 1, 3, and 4 are referred to by using the reference numerals in the respective drawings without particularly referring to the figure numbers.

  FIG. 5 is a functional block diagram. 4 is installed in the personal computer shown in FIG. 1 and FIG. 3, the personal computer operates as an example of the background replacement device according to the present invention.

  FIG. 5 shows a background replacement device 700 and a shooting environment determination device 800. A description of the shooting environment determination apparatus 800 will be given later.

  Further, FIG. 5 shows the photographing set 10 including the digital camera 11, the first flash light emitting device 12, and the second flash light emitting device 130, the printer 30, and the server 40, which are also shown in FIG.

  In the background replacement device 700 shown in FIG. 5, as described above, two photographed images photographed by the digital camera 11 of the photographing studio 10 are acquired, and the second flash light emitting device 130 among these two photographed images is acquired. Based on a photographed image obtained by flashing only the first flash light emitting device 12 (hereinafter, this photographed image is referred to as a backlight image), a photographed image obtained by flashing only the first flash light emitting device 12 (hereinafter, this photographed image). An image is referred to as a follow light image.) A background replacement process is performed in which a subject area and a background area are distinguished from each other, and the background area is replaced with a desired background. 710, a background replacement processing unit 720, an image data transfer unit 730, and an image display unit 740.

  The image acquisition unit 710 first receives RGB values representing two captured images that are captured by the digital camera 11 and transmitted from the digital camera 11. The image acquisition unit 710 acquires a background desired by the customer from the server 40 or from an input storage medium 540 such as a CD-ROM or a small storage medium. In this image acquisition unit 710, the CPU 211 of the personal computer 20 substantially controls the input interface 216, the FD drive 214, the CD-ROM drive 215, and the media drive 250 in accordance with the image acquisition unit 610 of the background replacement program 600. It is composed by doing.

  The background replacement processing unit 720 creates a background replacement image based on the two captured images (backlight image and normal image) acquired by the image acquisition unit 710. The background replacement processing unit 720 is substantially configured by the CPU 211 of the personal computer 20 operating according to the replacement processing unit 620 of the background replacement program 600.

  In the image data transfer unit 730, image data representing the background replacement image created by the background replacement processing unit 720 is sent to at least one of the printer 30 and the output storage medium 550 desired by the customer, and the background replacement device 700. The image is transferred to the image display unit 740. In the image data transfer unit 730, the CPU 211 of the personal computer 20 is substantially controlled by the output interface 217, the FD drive 214, the CD-ROM drive 215, and the media drive 250 in accordance with the image data transfer unit 630 of the background replacement program 600. It is configured by controlling.

  The image display unit 740 displays the background replacement image represented by the image data transferred from the image data transfer unit 730 on the display screen 220a. The image display unit 740 is substantially configured such that the CPU 211 of the personal computer 20 It is configured by controlling the image display device 220 according to the image display unit 640 of the replacement program 600.

  When image data representing a background replacement image is output from the image data transfer unit 730 to the printer 30, the printer 30 prints the background replacement image represented by the image data, and also transfers the image data. When the image data representing the background replacement image is output from the unit 730 to any output storage medium 550, the image data is written to the output storage medium 550. Then, both or one of the print paper on which the background replacement image is printed and the output storage medium 550 on which the image data representing the background replacement image is written is provided according to the customer's request.

  Next, details of the background replacement processing unit 720 will be described.

  6 and 7 are schematic diagrams illustrating an example of a follow light image and an example of a backlight image.

  FIG. 6 shows a follow light image of the subject P, and FIG. 7 shows backlight in which the region of the subject P is biased toward the shadow side and the region where the EL panel 130 is reflected as the background is biased toward the highlight side. An image is shown. Here, in the follow light image of FIG. 6, since the luminance of the light emission of the EL panel 130 is lower than the luminance of the flash light emitted from the flash light emitting device 12, the light emitting surface of the EL panel 130 appears whitish than the actual light emission color. On the other hand, in the backlight image shown in FIG. 7, it appears in blue-green, which is the actual emission color of the EL panel 130.

  As described above, in the backlight image shown in FIG. 7, the brightness of the subject P area and the background area are greatly different from each other, so that both can be easily distinguished. In this backlight image, the position and contour of the subject P in the image are substantially the same as the position and contour of the subject in the follow light image shown in FIG. Therefore, the background replacement processing unit 720 first distinguishes between the subject P and the background in the backlight image, and applies the distinction to the follow light image as it is to distinguish the subject P and the background in the follow light image. Then, the background replacement processing unit 720 generates a background replacement image by replacing the background in the follow light image with the background desired by the customer.

  FIG. 8 is a diagram showing details of the background replacement processing unit.

  The background replacement processing unit 720 shown in FIG. 8 executes the above-described background replacement processing shown by one block in FIG. 5 and includes a mask creation unit 721 and a background replacement image creation unit 722.

  In the backlight image shown in FIG. 7, the mask creation unit 721 defines a subject mask that defines a range in which only the subject color pixels are present in the backlight image, and a background mask that defines a range in which only the background color pixels are present. And create.

  FIG. 9 is a diagram showing details of the mask creation unit.

  The mask creation unit 721 includes a histogram creation unit 721a, a threshold calculation unit 721b, a subject mask setting unit 721c, and a background mask setting unit 721d, which are shown as one block in FIG.

  The histogram creation unit 721a creates a histogram for the brightness of each pixel constituting the backlight image.

  FIG. 10 is a diagram illustrating various examples of histograms regarding the brightness of each pixel constituting the backlight image.

  Here, the above-described forward light image and back light image are coordinates in the RGB color space that defines colors with three colors of R (red), G (green), and B (blue), that is, R in this RGB color space. The color of each pixel is represented by the value, the G value, and the B value. The R value, G value, and B value representing the color of each pixel reflect the brightness of the pixel. Therefore, here, a histogram of the brightness of each pixel constituting the backlight image is used. It can be created using any of the value, the G value, and the B value.

  Part (a) of FIG. 10 shows that the R value of each pixel constituting the backlight image is divided into a large number of ranges of the R value, and an R value histogram showing how many pixels are assigned to each range by frequency. H1 is shown, and in part (b) of FIG. 10, the G value of each pixel constituting the backlight image is assigned to a large range of G values, and how many pixels are assigned to each range. A G-value histogram H2 indicated by frequency is shown. In part (c) of FIG. 10, the B value of each pixel constituting the backlight image is assigned to a large range of B values, and the number of pixels assigned to each range is shown by frequency. A value histogram H3 is shown. In the R value histogram H1 shown in part (a) of FIG. 10, the R value is taken on the horizontal axis, and in the G value histogram H2 shown in part (b) of FIG. 10, the G value is taken on the horizontal axis. In the B value histogram H3 shown in Part (c) of FIG. Also, the frequency is taken on the vertical axis of these three histograms.

  In the backlight image, the background of the subject appears in blue-green, which is the emission color of the EL panel 130. Therefore, the brightness of each pixel of the backlight image is the G value among the R value, G value, and B value. Reflected best. Therefore, the histogram creation unit 721a shown in FIG. 9 is configured to create a G value histogram H2 shown in part (b) of FIG. 10 among the three histograms shown in FIG.

  Here, in the G value histogram H2 shown in part (b) of FIG. 10, the peak Pk1 and the peak Pk2 appear on the shadow side and the highlight side, respectively, as in the other three histograms. The shadow-side peak Pk1 appears after the pixels in the subject area in the backlight image are distributed, and the highlight-side peak Pk2 appears when the pixels in the background area in the backlight image are distributed.

  The threshold value calculation unit 721b illustrated in FIG. 9 calculates the following two threshold values based on the two peaks Pk1 and Pk2 in the G value histogram created by the histogram creation unit 721a. As shown in part (b) of FIG. 10, a threshold value Sr1 that is the upper limit of the G value at which the frequency is equal to or higher than the predetermined frequency α is detected from the peak Pk1 on the shadow side. Further, from the peak Pk2 on the highlight side, a threshold value Sr2 that is the lower limit of the G value at which the frequency is equal to or higher than the predetermined frequency α is detected at the peak Pk2.

  Then, the subject mask setting unit 721c shown in FIG. 9 uses, as a subject mask, an area composed of pixels having a G value equal to or less than the threshold value Sr1 among the plurality of pixels constituting the backlight image, and the background mask setting shown in FIG. The unit 721d sets a region composed of pixels having a G value equal to or greater than the threshold value Sr2 as a background mask.

  FIG. 11 is a diagram illustrating a region set as a subject mask and a region set as a background mask in the backlight image shown in FIG. 7.

  FIG. 11 shows a state in which the subject mask M1 indicated by hatching and the background mask M2 indicated by diagonal lines are overlaid on the entire follow-up image.

  The hatched portion in FIG. 11 is a portion that is greatly deviated toward the shadow side by backlight photographing, and the G value of the pixel in that portion is lower than the first threshold value Sr1. As a result, the hatched portion in FIG. 11 is set to the subject mask M1 by the subject mask setting unit 721c.

  Further, the hatched portion in FIG. 11 is a portion that is largely deviated toward the highlight side by backlight photographing, and the G value of the pixel in the portion exceeds the threshold value Sr2. As a result, the hatched portion in FIG. 11 is set to the background mask M2 by the background mask setting unit 721d.

  On the other hand, in the background replacement image creating unit 722 shown in FIG. 8, first, the area defined by the subject mask M1 is left as it is in the follow light image, and the area defined by the background mask M2 is changed to another desired by the customer. Replace the background to complete the background replacement image.

  The image data representing the background replacement image created in this way is transferred from the image data transfer unit 730 in FIG. 5 to each output device and output storage medium 550 (see FIG. 5).

  Here, the accuracy of the separation between the subject and the background in the background replacement device described above increases as the difference between the threshold value Sr1 and the threshold value Sr2 shown in part (b) of FIG.

  However, when the backlight system captures a backlight image, if the surroundings are bright, the subject is in a position where the light on the EL panel 130 is reflected, or the EL panel 130 is dirty, The difference between the brightness of the subject and the brightness of the background becomes small, and in the graph in part (b) of FIG. 10, there can be a situation where the distance between the threshold value Sr1 and the threshold value Sr2 is narrowed. There is a possibility that the background area and the subject area in the backlight image cannot be separated with high accuracy.

  Therefore, it is necessary to confirm whether or not the environment in which the photographing system 1 is installed is a photographing environment in which the background region and the subject region in the backlight image can be accurately separated before photographing the actual subject. . Hereinafter, a method for confirming the photographing environment will be described.

  FIG. 12 is a diagram showing the flow of the photographing environment confirmation method. This photographing environment confirmation method is an embodiment of the photographing environment confirmation method of the present invention. The photographing environment confirmation method is mainly performed by the photographing environment determination device 800 shown in FIG. 5 after photographing by the operator. The photographing environment determination apparatus 800 is substantially configured by the CPU 211 of the personal computer 20 operating according to the photographing environment determination unit 650 that is a part of the background replacement program 600. On the display screen 220a, the background replacement process and the shooting environment determination process can be switched and executed.

  In this imaging environment confirmation method, first, as step S1, a reference subject S whose upper surface is mirror-like and whose lower portion is transparent is placed on the mounting surface 131a, and only the light from the EL panel 130 illuminates the reference subject S from behind. Backlit shooting. The reason why such a reference subject S is used is that the reference subject S has a mirror surface at the top and is transparent at the bottom, so that it reflects light more easily than a normal subject, and the threshold value Sr1 is higher than that of a normal subject. When approaching Sr2, if the shooting environment has a minimum difference (value β described later) required to distinguish the background region and the subject region between the threshold value Sr1 and the threshold value Sr2, a normal subject This is because there is no problem as a shooting environment.

  FIG. 13 is a diagram illustrating a state of shooting the reference subject.

  FIG. 13 shows a reference subject S having an upper surface S1 having a mirror surface and a transparent lower portion S2.

  The backlight image of the reference subject S is displayed on the display screen 220a of the image display device 220 through the process of step S106 in FIG. The operator designates the subject area of the backlight image using the mouse 240. Although not shown, the imaging environment determination apparatus 800 shown in FIG. 5 can generate a histogram in the same manner as the background replacement apparatus 700. In the imaging environment determination apparatus 800, the subject area designated by the operator is displayed. A histogram relating to the G value is created for each of the background region other than the designated region. Returning to FIG. 12, the description will be continued.

  In step S2, a threshold value Sr1, which is the upper limit of the G value at which the appearance frequency is equal to or higher than the predetermined frequency α, is detected from the histogram relating to the G value of the subject area of the backlight image. Thereafter, in step S3, a threshold value Sr2 that is a lower limit of the G value at which the appearance frequency is equal to or higher than the predetermined frequency α is detected from the histogram related to the G value of the background region of the backlight image. In step S4, it is determined whether or not the threshold value Sr2 is larger than the threshold value Sr1 by exceeding the value β. If this condition is satisfied, it is assumed that the environment can be distinguished from the background area and the subject area, and this condition is satisfied. Otherwise, it is determined that the environment is difficult to distinguish between the background area and the subject area.

  FIG. 14 is a diagram showing a histogram relating to the G value of the backlight image of the reference subject.

  Part (a) of FIG. 14 shows a combination of histograms relating to the G values of the subject area and the background area of the backlight image of the reference subject S created by the shooting environment determination apparatus 800. The vertical axis represents the appearance frequency, and the horizontal axis represents the G value.

  In the histogram shown in part (a) of FIG. 14, the threshold value Sr1, which is the upper limit of the G value that is equal to or higher than the predetermined frequency α, is set for the reference subject S that tends to appear brighter than a normal subject. It is shown that it is closer to the highlight side than.

  Further, the histogram shown in part (a) of FIG. 14 shows that the threshold value Sr2 is larger than the threshold value Sr1 and exceeds the value β. The reason why the G value with the predetermined frequency α or higher is limited is to exclude noise components.

  Part (b) of FIG. 14 shows a histogram relating to the G value of the backlight image of the reference subject S when the EL panel 130 photographed as the background is dirty. Here, the threshold value Sr1 is shown in FIG. Although the threshold value Sr2 is closer to the shadow side than the part (a) in FIG. 14, the difference between the threshold value Sr2 and the threshold value Sr1 is equal to or less than the value β. It is shown.

  If it is determined that the difference between the threshold value Sr2 and the threshold value Sr1 is equal to or less than the value β, that is, it is difficult to distinguish between the subject area and the background area, the difference between the threshold value Sr2 and the threshold value Sr1 exceeds the value β. Corrective action is required. Therefore, in this imaging environment confirmation method, when it is determined that the difference between the threshold value Sr2 and the first threshold value Sr1 is equal to or less than the value β, illustration is omitted, but it is applied to the distributed EL element 132 together with a warning. Treatments such as an increase in AC voltage and wiping and cleaning of the EL panel 130 are displayed on the display screen 220a. If the difference between the threshold value Sr2 and the threshold value Sr1 increases beyond the value β by the operator performing the displayed procedure, the background area and the subject area can be distinguished.

  As described above, according to the photographing environment confirmation method of the present embodiment, it is possible to reliably confirm whether or not the photographing environment is such that a photographed image capable of distinguishing between the subject and the background is obtained.

It is a figure which shows the outline | summary of the imaging | photography system for producing a background replacement image. It is a flowchart which shows the flow of the process performed with the imaging | photography system of FIG. It is a hardware block diagram of the personal computer shown in FIG. It is a conceptual diagram which shows CD-ROM with which the background replacement program was memorize | stored. It is a functional block diagram. It is a schematic diagram which shows an example of a follow light image. It is a schematic diagram which shows an example of a backlight image. It is a figure which shows the detail of a background replacement process part. It is a figure which shows the detail of a mask preparation part. It is a figure which shows the various examples of the histogram about the brightness of each pixel which comprises a backlight image. FIG. 8 is a diagram illustrating an area set as a subject mask and an area set as a background mask in the backlight image shown in FIG. 7. It is a figure which shows the flow of the imaging | photography environment confirmation method. It is a figure which shows the mode of imaging | photography of a reference | standard subject. It is a figure which shows the histogram regarding G value of the backlight image of a reference | standard subject.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shooting system 10 Shooting studio 11 Digital camera 12 Flash light emitting device 130 EL panel 131 Case 131a Mounting surface 131b Back surface 132 Dispersion type EL element 14 Power source 20 Personal computer 210 Main unit 211 CPU
212 Main Memory 213 Hard Disk Device 214 FD Drive 215 CD-ROM Drive 30 Printer 40 Server 600 Background Replacement Program 610 Image Acquisition Unit 620 Replacement Processing Unit 630 Image Data Transfer Unit 640 Image Display Unit 700 Background Replacement Device 710 Image Acquisition Unit 720 Background Replacement Processing unit 721 Mask creation unit 721a Histogram creation unit 721b Threshold calculation unit 721c Subject mask setting unit 721d Background mask setting unit 722 Background replacement image creation unit 730 Image data transfer unit 740 Image display unit

Claims (3)

A shooting process of obtaining a shot image by irradiating a known reference subject for confirming the shooting environment with light from a predetermined background surface, and shooting the reference subject from the opposite side of the reference subject with respect to the background surface; ,
A first brightness analysis step of analyzing the brightness of a known subject area in which the reference subject is captured with respect to a photographed image obtained in the photographing step;
A second brightness analysis process for analyzing the brightness of a known background area in which the background of the reference subject is reflected in the captured image obtained in the shooting process;
And a determination process for determining whether or not the brightness of the background area is brighter than the brightness of the subject area and the difference in brightness exceeds a predetermined level. .   2. The photographing environment confirmation method according to claim 1, wherein the reference subject has a mirror-like part on at least a part of the surface.   3. The photographing environment confirmation method according to claim 1, wherein the reference subject has at least a transmission part that transmits light from the background surface.

Images