JP2006203688A - Imaging apparatus and foreign material detecting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology capable of easily detecting foreign materials by using the existing element mounted on a camera without bothering a photographer. <P>SOLUTION: This imaging apparatus comprises: an imaging means for imaging the optical image of an object; a generating means for generating a comparison image for foreign material detection from a photographed image in normal photographing for performing object photographing by the imaging means; a recording means for associating the comparison image with a photographing condition obtained from the photographed image and recording them; and a determining means for determining whether foreign materials are present on the imaging surface of the imaging means by using the comparison image and the photographing condition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus such as an electronic still camera and a foreign object detection method thereof.

  Conventionally, in an electronic still camera with a replaceable lens and using a focal plane shutter, the mirror box has a hermetically sealed structure to prevent dust or other foreign matter from adhering to the image sensor. The surface of the filter (low-pass filter or infrared cut filter) to be separated from the focal plane of the image sensor as much as possible so that it does not focus on the foreign material, or the foreign material on the filter is dropped by ultrasonic vibration ing.

In addition, a technique has been proposed in which pixels that do not change in contrast or the like are detected as a foreign substance region from a plurality of different images and reflected in image processing for cleaning the image sensor or correcting the foreign substance region (for example, Patent Documents). (See 1)
JP 2004-172820 A

  However, even if the mirror box is sealed to prevent foreign matter from adhering to the image sensor as described above, foreign matter generated from a mechanical mechanism such as a debris from the focal plane shutter cannot be prevented. . There is also a method to keep the surface of the filter (low-pass filter or infrared cut filter) placed on the image sensor as far as possible from the focal plane of the image sensor so that the foreign object is not focused. The further away the focal plane, the lower the shutter efficiency of the focal plane shutter. Further, it is expensive to remove foreign matter on the filter by ultrasonic vibration. In foreign matter detection, there are foreign matter detection using infrared light and image processing with film scanners, etc., but it is easy to automatically remove foreign matter at low cost with the elements mounted on the camera. The detection method has not been realized.

  Further, since the foreign object detection described in Patent Document 1 is executed in the foreign object detection mode, the foreign object cannot be detected in the normal photographing mode. In addition, there is an annoyance that the photographer must perform an image capturing operation even in the foreign object detection mode.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of easily detecting a foreign object using an existing element mounted on a camera without bothering a photographer.

  In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging unit that captures an optical image of a subject, and foreign object detection from a captured image during normal shooting of the subject by the imaging unit. Generating means for generating the comparison image, recording means for associating and recording the comparison image and the photographing condition obtained from the photographed image, and using the comparison image and the photographing condition on the imaging surface of the imaging means. Determining means for determining whether or not a foreign object exists.

  The foreign object detection method for an imaging apparatus according to the present invention is a foreign object detection method for an imaging apparatus in which an optical image of a subject is formed on an imaging surface, and the foreign object is detected from a captured image during normal shooting of the subject. A generation process for generating a detection comparison image, a recording process for recording the comparison image and a shooting condition obtained from the captured image in association with each other, and a foreign object on the imaging surface using the comparison image and the shooting condition And a determination step of determining whether or not exists.

  The program of the present invention is a program for executing a foreign object detection method of an image pickup apparatus that forms an optical image of a subject on an image pickup surface and picks up an image. Using a generation process code for generating a comparison image for detecting foreign matter, a recording process code for recording the comparison image and a shooting condition obtained from the captured image, the comparison image, and the shooting condition And a code of a determination step for determining whether or not a foreign substance exists on the imaging surface.

  According to the present invention, no special mode setting or photographing operation for foreign object detection is required, and it can be realized at low cost using an existing configuration. In addition, the foreign object detection accuracy is improved by using imaging conditions and the like. Therefore, it is possible to reduce the problem that foreign matter appears in the captured image.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  The embodiment described below is an example as means for realizing the present invention, and should be appropriately modified or changed according to the configuration and various conditions of the apparatus to which the present invention is applied. It is not limited to the embodiment.

[First Embodiment]
Hereinafter, a foreign object detection using the photographed image and the photographed data, which is a feature of the present invention, and an electronic camera for realizing it will be described.

<Camera configuration>
FIG. 1 is a schematic block diagram of an electronic camera applied as an embodiment according to the present invention.

  Reference numeral 1 denotes a lens unit on which an interchangeable photographic lens is mounted, but it may be a zoom lens. The lens unit 1 communicates with the microcomputer 16, and an internal AF (autofocus) drive circuit 1 a is constituted by, for example, a stepping motor, and the focus lens position in the lens unit 1 is displaced by controlling the microcomputer 16. Adjust. The defocus amount used for the focus calculation is calculated using the output of the AF sensor 24. An aperture driving circuit 1b is provided in the lens unit 1, and an optical aperture value is changed under the control of the microcomputer 16. Further, the microcomputer 16 can communicate with the lens unit 1 and acquire information on the current zoom position (focal length information) and the current separation position (subject distance).

  A quick return mirror 2 is moved up and down by an actuator (not shown) in response to a command from the microcomputer 16 during exposure. Further, the mirror 2 is composed of a half mirror for guiding light to the AF optical system, and the sub mirror is also interlocked.

  Reference numeral 3 denotes a focusing screen. The photographer can confirm the focus and composition of the optical image of the subject obtained through the lens unit 1 by observing the focusing screen through the pentaprism 4 and a finder optical system (not shown). .

  A focal plane shutter 5 can freely control the exposure time of the image sensor 6 under the control of the microcomputer 16. The focal plane shutter is generally composed of a front curtain and a rear curtain, and a free exposure time is controlled by an interval between the two curtains.

  A CCD, CMOS sensor, or the like is used as the image sensor 6, and a subject image formed on the image sensor 6 through the lens unit 1 is photoelectrically converted and captured as an electric signal.

  The clamp / CDS (correlated double sampling) unit 7 and the AGC (auto gain control) unit 8 perform basic analog processing before A / D conversion to reduce noise of the image signal converted into an electric signal and to reduce the signal level. Make adjustments. Further, the microcomputer 16 can change the clamp level and the AGC reference level.

  The A / D conversion unit 9 converts the image signal that is an analog signal subjected to the analog processing into image data that is a digital signal. This conversion is performed according to the set ISO sensitivity.

  The video signal processing circuit 10 performs filter processing, color conversion processing, and gamma / knee processing on the image data converted into the digital signal, and outputs the result to the memory controller 13. On the other hand, the video signal processing circuit 10 has a built-in D / A conversion circuit, and the image data converted into a digital signal by the A / D conversion unit 9 and the image data input from the memory controller 13 are converted into analog signals. And can be output to the liquid crystal display unit 12 through the liquid crystal driving circuit 11. Image processing and display processing by the video signal processing circuit 10 are switched by the microcomputer 16. Further, the microcomputer 16 performs white balance adjustment based on the color balance information of the photographed image. Further, the video signal processing circuit 10 performs image creation processing for creating a plurality of images for detecting foreign matter, which is a feature of the present embodiment, and foreign matter detection processing for detecting foreign matter by comparing the created images.

  Further, the video signal processing circuit 10 does not perform the image processing as described above on the A / D converted image data in accordance with a command from the microcomputer 16 and adds only information on the imaging conditions described later, It is also possible to store in the buffer memory 19 through the memory controller 13. The video signal processing circuit 10 also has a compression processing function such as JPEG, and stores the image data in the memory 14 after compressing the image data.

  When shooting in the continuous shooting mode, image data that has been shot is temporarily stored in the buffer memory 19, and is later processed through the memory controller 13 when the load state of the video signal processing circuit 10 is at a level that allows image processing. The image data is read from the buffer memory 19, and the video signal processing circuit 10 performs image processing and compression processing to increase the continuous shooting speed. The number of continuous shots greatly depends on the capacity of the buffer memory 19.

  The microcomputer 16 detects the remaining capacity of the memory 14 through the memory controller 13 based on the predicted value data of the image size corresponding to the ISO sensitivity, the image size, and the image quality set before photographing. The remaining number of images that can be captured is calculated by dividing by the capacity per image based on the image size, and the number of remaining images that can be captured is displayed on the liquid crystal display unit 12.

  The memory controller 13 stores unprocessed image data input from the video signal processing circuit 10 in the buffer memory 19, stores image-processed digital image data in the memory 14, and conversely, the buffer memory 19 and the memory Image data is taken out from 14 and output to the video signal processing circuit 10. The memory controller 13 stores image data sent from a PC or the like through an external interface 15 such as USB (Universal Serial Bus) or IEEE1394 (Institute of Electrical and Electronics Engineers 1394) in the memory 14 or vice versa. The image data stored in the memory 14 can be output via the external interface 15. Note that the memory 14 may be detachable. As the removable memory 14, a memory card such as a compact flash (registered trademark) can be considered.

  A foreign object detection image, which will be described later, is converted into a binary image represented by white and black, and stored in the memory 14 in, for example, a bitmap (BMP) format.

  Further, the information related to the imaging condition of the original image of the foreign object detection image is associated as supplementary information with the header portion of the foreign object detection image, or has a link with the foreign object detection image as an information holding file. It is stored in the memory 14 or the buffer memory 19 independently in the form.

  The power supply unit 17 supplies power necessary for each IC and drive system.

  The operation member 18 transmits an operation state to the microcomputer 16, and the microcomputer 16 controls each part according to the change of the operation state.

  Reference numerals 20 a and 20 b denote release buttons, which are input switches of the operation member 18. When only SW1 of 20a is on, the release button is half-pressed. When both SW1 of 20a and SW2 of 20b are both on, shooting is performed with the release button on.

  In addition to the release buttons 20a and 20b, the operation member 18 is connected to switches (not shown) such as an ISO setting button, an image size setting button, an image quality setting button, an information display button, and the operation state of each switch is input. The In the present embodiment, since a foreign object detection image is created from a normal captured image, a foreign object detection mode, a switch for switching to the mode, and the like are not provided.

  A liquid crystal drive circuit 21 drives the external liquid crystal display unit 22 and the in-finder liquid crystal display unit 23 in accordance with the contents of the display command from the microcomputer 16. Further, a backlight such as an LED (not shown) is disposed in the in-finder liquid crystal display unit 23, and the LED is also driven by the liquid crystal driving circuit 21.

  Reference numeral 24 denotes an AF sensor that outputs defocus information to the microcomputer 16, controls the lens unit 1 based on the defocus information, and focuses using the internal AF lens driving circuit 1a.

  Reference numeral 25 denotes an AE sensor that measures the light on the viewfinder screen and measures the luminance of the subject through the lens unit 1.

  In addition, the output of a sensor 27 that detects the direction is input to the microcomputer 16.

  The microcomputer 16 receives the output of a sensor 26 that detects camera shake.

<Camera operation>
Next, the overall operation of the camera used in this embodiment will be described using the flowchart of FIG. The following steps are performed by the microcomputer 16 unless otherwise specified.

  S301: When the process is started, it is determined whether or not the power-off timer has timed out. If it is determined that the time-out has occurred, the process proceeds to S320 for power-off processing. If not timed out, the process proceeds to S302.

  S302: Various settings such as ISO sensitivity, image size, image quality, and the like are performed by a switch connected to the operation member 18. Further, setting of an operation mode of the camera, a shooting mode (for example, continuous shooting), and the like are performed by a switch operation via the operation member 18.

  S303: The brightness of the subject is measured using the AE sensor 25, and the shutter time and aperture value for obtaining a proper exposure are calculated.

  S304: The defocus amount of the subject is detected using the AF sensor 24, and the lens unit 1 is driven to the in-focus position by the AF driving circuit 1a.

  S305: Various setting states such as the operation mode and photographing mode set in S302 are displayed on the external liquid crystal display unit 22 and the in-viewfinder liquid crystal display unit 23. Further, the in-focus state detected in S303 and S304 and the shutter time and aperture value calculated in S303 are displayed on the liquid crystal display unit 12 via the video signal processing circuit 10.

  S306: It is determined whether or not the release buttons 20a and 20b are in a half-pressed state by an input operation from the operation member 18, and if only 20a is in a half-pressed state, the process proceeds to S307 for timer update and is not pressed at all. In a state where neither 20a nor 20b is pressed, the process returns to S301.

  S307: Update the power OFF timer.

  S308: It is determined whether or not the release is possible and the release buttons 20a and 20b are completely pressed (20a and 20b are simultaneously turned on). The process proceeds to S309 for shooting, and if not pressed, the process returns to S301.

  S309: The quick return mirror 2 is controlled to bring the mirror up, and the lens aperture is controlled to the lens unit 1 to the aperture value calculated in S303.

  S310: The focal plane shutter 5 controls the shutter time calculated in S303, and the clamp / CDS unit 7 and the AGC unit 8 perform basic analog processing on the image signal captured by the image sensor 6. The A / D converter 9 converts the image signal that is an analog signal subjected to the analog processing into image data that is a digital signal.

  S311: The quick return mirror 2 is controlled to return the mirror to the down state, and the lens aperture is controlled to the open state with respect to the lens unit 1.

  S 312: The ISO sensitivity is adjusted based on the gain value for the ISO value set in the AGC unit 8 by the video signal processing circuit 10, the image data is sent to the memory controller 13, and temporarily stored in the buffer memory 19.

  S313: Based on the white balance information acquired from the video signal processing circuit 10, the gain of each color component of R, G, B used in the video signal processing circuit 10 is calculated so as to obtain an appropriate color, and white balance adjustment is performed. .

  S314: When the load state of the video signal processing circuit 10 is a level at which image processing is possible, unprocessed image data is read from the buffer memory 19 through the memory controller 13 and subjected to image processing and compression processing. Start the save operation. In the continuous shooting mode or the like, the captured images are sequentially stored in the buffer memory 19, but the image processing may be stopped.

  S315: The microcomputer 16 detects the remaining capacity of the memory 14 through the memory controller 13 based on the predicted value data of the image size corresponding to the ISO sensitivity, the image size, and the image quality set in S302. Is divided by the capacity per image based on the image size, etc. to calculate the remaining number of images that can be captured, and the remaining number of images that can be captured is displayed on the liquid crystal display unit 12.

  S316: The image signal processed in S314 is sent to the liquid crystal drive circuit 11 and displayed on the liquid crystal display unit 12. Further, the photographing information determined in S303, S304, and S315 is sent to the liquid crystal driving circuit 21 and displayed on the external liquid crystal display unit 22 and the in-viewfinder liquid crystal display unit 23.

  S317: Compared with images taken in the past, it is detected whether there is a luminance level equal to or less than a luminance level at the same location, and the size relative to the screen is also detected.

  S318: Taking into consideration the unprocessed captured image stored in the buffer memory 19, it is determined whether or not the next shoot is possible by determining whether there is a storable area in the memory 14, and the shoot is possible. If it is, the process returns to S301, and if the photographing is not possible, the process proceeds to S319 in order to display a warning.

  S319: A message indicating that it is determined that shooting is not possible in S318 is displayed on the liquid crystal display unit 12.

  S320: If it is determined in S301 that the timeout has occurred, the liquid crystal display circuit 12 is turned off by the liquid crystal drive circuit 11 as the power-off process, and the backlight of the in-viewfinder liquid crystal display section 23 is also turned off.

  S321: Wait until the image processing and compression processing in S314 and the storage of the image data in the memory are all finished, and the captured image area of the buffer memory 19 becomes empty.

  S322: The power supply unit 17 is controlled to stop the power supply unnecessary for photographing.

<Foreign matter detection processing>
First, before describing the foreign object detection process of the present embodiment, the characteristics of an image in which the foreign object, which is the premise of the present embodiment, is described with reference to FIG.

  4A is an original image in which mountains, trees, and clouds as subjects are reflected in color, and FIG. 4B is an image of the original image in FIG. 4A with a predetermined luminance level as a threshold. The extracted foreign matter 4a and the subject tree 4b are binarized and extracted as “1 (black)” below a predetermined luminance level, and the others as “0 (white)”.

FIG. 4C shows an original image (not shown) which is another color image whose focus is changed from FIG. 4A and is not focused on the subject tree 4b. A subject is extracted, and the shaded portion of the subject tree 4b indicates a portion out of focus.
FIG. 4D shows an original image (not shown), which is another color image in which the subject is zoomed in on the original image in FIG. Similarly, with a predetermined luminance level as a threshold, the captured foreign matter 4a and the subject tree 4b are binarized to “1 (black)” below the predetermined luminance level, and the others are binarized to “0 (white)”. Extracted.

  Further, FIG. 4 (e) shows an object having a predetermined luminance level or less extracted from an original image (not shown), which is another color image in which the object tree 4b is shifted left and right due to camera shake or the like. The shaded portion of the tree 4b that is the subject indicates a blurred portion.

  Here, when FIG. 4B is compared with FIGS. 4C to 4E, it can be seen that the portion where the foreign matter 4a on the upper left of the screen is present is always the same. In other words, the foreign matter on the image sensor 6 is always placed on the same pixel with respect to the pixels of the image sensor, whereas the subject image changes in the image formation state on the image sensor depending on the shooting conditions. The presence or absence of a foreign object can be determined by comparing two or more images having different values. In addition, when generating a binarized image as described above, it is assumed that the foreign matter reflected in the subject is black. For example, a black portion is preferentially extracted, and If a subject that seems to be close as a result of distance measurement is extracted at the same time, foreign objects can be extracted using luminance information and distance measurement information.

  Using this feature, in this embodiment, as described with reference to FIG. 3B, images having different focal lengths, images having different shooting distances, camera shake information, and the like are compared based on shooting conditions. To detect foreign matter with high accuracy.

  Here, the foreign object detection processing of the present embodiment will be described with reference to the flowcharts of FIGS.

  FIG. 3A is a flow showing a process for creating a foreign object detection image from a normal captured image, which is included in a part of the process in S314 of FIG. 2, and FIG. 3B is a flowchart of S317 of FIG. It is a flowchart which shows a foreign material detection process.

  Note that an image creation process for creating a plurality of foreign object detection images described below and a foreign object detection process for detecting a foreign object by comparing the images are performed by a video signal processing circuit 10 at a time of normal photographing. This is executed during image processing.

S 101: First, the video signal processing circuit 10 reads a captured image from the buffer memory 19.
S102: Next, a foreign object detection image is created by binarizing the photographed image read out in S101 to “1 (black)” below a predetermined luminance level and “0 (white)” otherwise. .

  S103: The foreign object detection image created in S102 and the shooting condition of the original shot image are associated with each other and recorded in the buffer memory 19 or the memory 14 through the memory controller 13. The shooting conditions include focal length information and subject distance information that can be acquired from the lens unit 1, AV value, TV value, ISO sensitivity, camera shake detection amount detected by the camera shake detection sensor 26, or direction detection sensor 27. Includes shooting direction information.

  Next, a foreign object detection process using the foreign object detection image and the imaging conditions recorded in the flow of FIG. 3A will be described with reference to the flowchart of FIG.

  S104: The video signal processing circuit 10 captures the currently captured image and the image from the foreign object detection image and the image capturing conditions recorded in S102 (a plurality of these sets are already stored in the buffer memory 19 or the memory 14). Select and read data with different conditions.

S105: Next, a foreign object detection image is created from the image taken now, and compared with the foreign object detection image selected in S104.
S106: Here, as a result of the comparison in S105, for example, the one that differs only in the focal length, the one that differs only in the photographing distance, or the one that differs only in the photographing direction is selected from the photographing conditions of the foreign object detection image, and compared with the image taken now If there is a binarized “1” area having the same area, the same shape, and the same position, it is determined that there is a foreign object.

  S107: When it is determined that there is a foreign object in S106, a warning is displayed on the liquid crystal display unit 12.

  According to the above embodiment, the foreign object detection image is separately created and accumulated from the captured image, so that no special mode setting or photographing operation for detecting the foreign object is required, and the existing configuration is used at low cost. Can be realized. Further, foreign matter detection can be performed with high accuracy by using photographing information such as photographing conditions.

  As a result, it is possible to reduce the problem of foreign objects appearing in the captured image.

[Second Embodiment]
In the first embodiment, the foreign object detection is performed using the foreign object detection image. However, in the second embodiment, the binarized image is divided into a plurality of blocks, and “1” in each block is continuous. Foreign matter is detected by comparing the number of pixels to be compared (comparative image) for each block.

  FIGS. 5A and 5C are binarized to “1 (black)” below a predetermined luminance level and “0 (white)” other than a predetermined luminance level for a photographed image taken by changing only the focal length. The foreign object detection image created by doing this is shown, and the foreign object is reflected in the upper left.

  In the present embodiment, as shown in FIGS. 5B and 5D, one image binarized from the captured image is divided into 6 blocks in association with the above-described shooting conditions, The number of pixels in which “1” is consecutive and the block position are recorded in the buffer memory 19. By storing these pieces of information not in the memory 14 but in the buffer memory 19, the memory 14 is omitted, and at the same time, the processing speed required for foreign object detection is increased. This is because if the memory 14 is a removable medium, the information stored for detecting foreign matter will be lost if the medium is replaced. In order to increase the detection accuracy, the number of blocks may be increased. However, here, an example in which the number of blocks is divided into six blocks will be described for easy explanation. Further, as described above, each block position and the number of pixels are stored in the buffer memory 19 in association with the header portion of the foreign matter detection image data or the information holding file.

  First, among the pixel values in each block, the number of consecutive 1 (black in the figure) pixels is counted and recorded in the buffer memory 19 together with the corresponding block position. In this example, for convenience of explanation, there is only one location where one pixel is continuous in each block, but if there are a plurality of locations, the number is also recorded. Then, for images with different shooting conditions (focal length in this example), the numerical values for each block are compared, and if there is a block with the same numerical value (for example, 5), there is a possibility that there is a foreign object in that block. Judgment is high.

  FIGS. 6A and 6B are flowcharts showing the foreign object detection process of the second embodiment. The foreign object detection processing described below is executed by the video signal processing circuit 10 during image processing of a captured image during normal shooting.

  S601: The video signal processing circuit 10 reads out the captured image from the buffer memory 19.

  S602: The photographed image read out in S601 is binarized to “1 (black)” below a predetermined luminance level and “0 (white)” otherwise.

  S603: The video signal processing circuit 10 divides the foreign object detection image created in S602 into a plurality of blocks, and counts and corresponds to the number of consecutive 1 (black) pixels among the pixel values in each block. It is recorded in the buffer memory 19 together with the block position (coordinate value).

  Next, a foreign object detection process using the number of pixels and block positions recorded in the flow of FIG. 6A and imaging conditions will be described with reference to the flowchart of FIG.

  S604: The video signal processing circuit 10 determines the currently captured image and the shooting conditions from the number of pixels and the block position recorded in S603 and the shooting conditions (a plurality of these sets are already stored in the buffer memory 19). Select a different one to read.

  S605: Next, the number of pixels selected in S604 and the block position are compared with the number of pixels for each block of the image just taken.

  S606: Here, if there is a block having the same numerical value as a result of the comparison in S605, it is determined that there is a foreign object candidate in that block.

  S607: When it is determined in S606 that there is a foreign object candidate, a warning is displayed on the liquid crystal display unit 12.

  According to the above embodiment, in addition to the effects of the first embodiment, the memory 14 can be omitted, and the detection speed can be increased at the same time.

[Third Embodiment]
In the first embodiment, a foreign object detection image is created for each photographed image, and the photographing conditions are recorded together with the foreign object detection image. In the third embodiment, a foreign object detection image created in the past is recorded. When the image and shooting conditions are the same, the recording capacity of the memory is reduced by not creating and recording a new foreign object captured image.

  FIG. 7 is a flowchart showing processing for creating a foreign object detection image according to the third embodiment. The foreign object detection processing described below is executed by the video signal processing circuit 10 during image processing of a captured image during normal shooting.

  S701: First, the video signal processing circuit 10 reads a captured image from the buffer memory 19.

  S702: Next, it is determined whether or not the captured image read in S701 is an effective image for creating a video foreign object detection image. That is, it is determined that the object is effective if the focal length is changed or the photographing direction is different, for example, by comparing with the photographing conditions of the foreign object photographing images created and recorded so far. On the other hand, if the photographing conditions are the same, it is determined that it is not effective for detecting foreign matter.

  S703: Next, the captured image determined to be effective in S701 is binarized using a predetermined luminance level as a threshold value to create a foreign object detection image.

  S704: Next, the foreign object detection image created in S703 and the shooting conditions are associated and recorded in the buffer memory 19 or the memory 14.

  Then, as in FIG. 3B, the foreign object detection process is executed using the foreign object detection images recorded in S704 with different shooting conditions.

  According to the above embodiment, in addition to the effects of the first embodiment, a captured image with different shooting conditions is selected as an effective one, and a foreign object detection image is created and stored. It is possible to record only those under different shooting conditions, and the finite memory in the camera can be used effectively.

  In the third embodiment, instead of the foreign object detection image, the foreign object may be detected using the block position and the number of pixels of the second embodiment described above. The effects of the embodiment are also added.

[Fourth Embodiment]
In the first embodiment, a foreign object detection image is created for each shooting, and shooting conditions are recorded together with the foreign object detection image. In the third embodiment, when the shooting conditions are the same, a new foreign object detection image is created. And the aspect which does not record was demonstrated. In the fourth embodiment, in addition to this, shooting date / time information is added to the foreign object detection image, and a period retroactive to a predetermined time with respect to the current date / time is managed as the expiration date.

  FIG. 8 is a flowchart showing a foreign object detection process according to the fourth embodiment. The foreign object detection processing described below is executed by the video signal processing circuit 10 during image processing of a captured image during normal shooting. In the present embodiment, the shooting date / time information is recorded in addition to the shooting conditions when the foreign object detection image is recorded in the memory.

  S801: First, the video signal processing circuit 10 starts from a foreign object detection image recorded in the memory 14 through the memory controller 13 and shooting conditions (a plurality of these sets are already stored in the buffer memory 19 or the memory 14). Select and read out images that have different shooting conditions from the current image.

  S802: Next, it is determined whether or not the shooting date and time information added to the foreign object detection image read out in S801 is within a predetermined expiration date (for example, within one week), and if it is within the expiration date, the process proceeds to S803. If the expiration date has passed, the process proceeds to S806.

  S803: The foreign object detection image selected in S801 is compared with the image just taken.

  S804: Here, as a result of the comparison in S803, for example, the one that differs only in focal length, the one that differs only in the photographing distance, or the one that differs only in the photographing direction is selected from the photographing conditions of the foreign object detection image, and compared with the image taken now If there is a binarized “1” area having the same area, the same shape, and the same position, it is determined that there is a foreign object.

  S805: When it is determined in S804 that there is a foreign object, a warning is displayed on the liquid crystal display unit 12.

  S806: On the other hand, the foreign object detection image whose photographing date and time has passed the expiration date is deemed unsuitable for foreign object detection, and is erased from the memory 14 together with the photographing conditions associated therewith, and the process returns to S801.

  In this embodiment, the expiration date is determined for the foreign object detection image selected at the time of the foreign object detection process, but at regular intervals (every week) or at a determined timing (for example, when the power is turned on). You may make it check an expiration date about the image in memory.

  According to the embodiment, the foreign object detection with higher accuracy can be performed by using the foreign object detection image within the expiration date. In other words, since foreign matter may increase or decrease or move, it is desirable to use an image with a close photographing date and time for foreign matter detection. In the present embodiment, since the foreign object detection image is automatically created and stored from the normal captured image without the photographer being aware of it, the image is stored unless it is automatically deleted at a specific date and time. It is an effective means to add an expiration date to the foreign object detection image. In the fourth embodiment, instead of the foreign object detection image, the foreign object may be detected using the block position and the number of pixels of the second embodiment described above. The effects of the embodiment are also added.

[Other Embodiments]
Another object of the present invention is to supply a storage medium storing a program code of software for realizing the foreign object detection function of the above-described embodiment to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus. Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium.
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM or the like is used. I can do it.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the computer based on an instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion board or function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

It is a schematic block diagram of the electronic camera applied as embodiment which concerns on this invention. It is a flowchart which shows the whole operation | movement of a camera. (A) is a flowchart showing processing for creating a foreign object detection image of the first embodiment, and (b) is a flowchart showing foreign object detection processing of the first embodiment. It is a figure explaining the characteristic which the image in which the foreign material was reflected, and the foreign material detection method have. It is a figure explaining the foreign material detection process of 2nd Embodiment. (A) is a flowchart which shows the process which produces the image for a foreign material detection of 2nd Embodiment, (b) is a flowchart which shows the foreign material detection process of 2nd Embodiment. It is a flowchart which shows the process which produces the image for a foreign material detection of 3rd Embodiment. It is a flowchart which shows the foreign material detection process of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens unit 2 Quick return mirror 3 Finder screen 4 Penta prism 5 Focal plane shutter 6 Image pick-up element 7 Clamp / CDS part 8 AGC part 9 A / D conversion part 10 Video signal processing circuit 11 Liquid crystal drive circuit 12 Liquid crystal display part 13 Memory controller 14 Memory 15 External interface 16 Microcomputer 17 Power supply unit 18 Operation member 19 Buffer memory 20a, 20b Release button 21 Liquid crystal drive circuit 22 External liquid crystal display unit 23 Liquid crystal display unit in viewfinder 24 AF sensor 25 AE sensor 26 Camera shake detection sensor 27 Direction detection sensor

Claims (13)

Imaging means for capturing an optical image of a subject;
Generating means for generating a comparison image for detecting foreign matter from a photographed image at the time of normal photographing for photographing an object by the imaging means;
A recording unit that records the comparison image and the imaging condition obtained from the captured image in association with each other;
An imaging apparatus comprising: a determination unit that determines whether or not a foreign object exists on an imaging surface of the imaging unit using the comparison image and the imaging condition.   The imaging apparatus according to claim 1, wherein the determination unit compares a plurality of comparative images having different imaging conditions, and determines that there is a foreign object when there is a region whose value does not change in each image.   The determination unit divides the comparison image into a plurality of blocks, compares the comparison images having different shooting conditions with respect to the result of counting the number of pixels that take a continuous value in each block, and detects a foreign object in the block having the same number of pixels. The imaging apparatus according to claim 1, wherein it is determined that there is an image.   The imaging apparatus according to claim 1, wherein when the newly generated comparison image has the same shooting condition as the image generated in the past, recording to the recording unit is not performed. Recording shooting date and time information as a recording condition in a recording means,
The determination means determines the presence or absence of foreign matter using an image within a predetermined period from the shooting date and time,
The image pickup apparatus according to claim 1, wherein the image after the predetermined period and the photographing condition thereof are deleted from the recording unit.   The shooting condition includes at least one of focal length information of the imaging lens, shooting distance information to the subject, camera shake information detected by the camera shake detection unit, and direction information at the time of shooting detected by the direction detection unit. The imaging apparatus according to claim 1, wherein the imaging apparatus is characterized in that: A foreign matter detection method for an imaging apparatus that images an object by forming an optical image on an imaging surface,
A generation process for generating a comparison image for detecting foreign matter from a captured image during normal shooting for shooting a subject,
A recording step of recording the comparison image and the imaging condition obtained from the captured image in association with each other;
A foreign matter detection method comprising: a determination step of determining whether or not a foreign matter is present on the imaging surface using the comparison image and the imaging condition.   8. The foreign object detection method according to claim 7, wherein in the determination step, a plurality of comparative images having different imaging conditions are compared, and if there is a region whose value does not change in each image, it is determined that there is a foreign object. .   In the determination step, the comparison image is divided into a plurality of blocks, and the number of pixels having consecutive values in each block is counted, and comparison images with different shooting conditions are compared. The foreign object detection method according to claim 7, wherein it is determined that there is an object.   The foreign object detection method according to claim 7, wherein when the newly generated comparative image has the same shooting conditions as the image generated in the past, the recording in the recording step is not performed. In the recording step, shooting date / time information is recorded as the shooting condition,
8. The determination step according to claim 7, wherein the presence / absence of a foreign object is determined using an image within a predetermined period from the shooting date and time, and an image that has passed the predetermined period and its shooting conditions are deleted from a recording unit. The foreign matter detection method described.   8. The photographing condition includes at least one of focal length information of an imaging lens, photographing distance information to a subject, camera shake information, and direction information at the time of photographing detected by a direction detecting unit. The foreign object detection method according to any one of 11.   A program for causing a computer of an imaging apparatus to execute the foreign object detection method according to any one of claims 7 to 12.

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