JP4306399B2 - Digital camera - Google Patents

Description

  The present invention relates to a digital camera that identifies feature points of a person and performs focusing or exposure according to the identification result.

  2. Description of the Related Art Conventionally, many techniques for identifying a person from image data have been known, including a system that authenticates a person by registering a fingerprint or iris feature point in advance and collating it with the feature point. Japanese Patent Application Laid-Open No. 9-251534 describes in detail how to identify eyes as a person by extracting eyes, nose, mouth, etc., registering them as feature points, and comparing them with feature points extracted from the input image. Japanese Patent Laid-Open No. 10-232934 discloses a method for increasing the accuracy of a dictionary image when registering feature points extracted in this way. Examples of applying these technologies to cameras are given below.

  Japanese Patent Application Laid-Open No. 2001-201779 registers a camera user as reference information in advance, and only when the camera user matches the identification information input by photographing the camera toward his / her face. A camera that enables operation is disclosed. Japanese Patent Application Laid-Open No. 2001-309225 discloses a camera in which data such as face coordinates, dimensions, eye positions, head poses, and the like recognized by a face recognition algorithm are recorded together with image data in an image memory. Japanese Patent Application Laid-Open No. 2001-326841 discloses an image pickup apparatus (digital camera) that stores identification information (face, fingerprint, palm print) for identifying a regular user in advance. Japanese Patent Laid-Open No. 2002-232761 discloses an image recording apparatus that records in association with identification information of a subject that has been read in advance on a captured image. Japanese Patent Application Laid-Open No. 2002-333651 discloses a photographing apparatus that generates a recording signal by comparing preliminarily stored appearance information and photographing face information. This appearance information is recorded together with the priority.

  The invention of applying the above-described technology for identifying a subject to a camera is that the technology conventionally performed in a large-scale computer system can be performed simply by a camera alone. If an attempt is made to shoot using this identification technology, an unprecedented camera operation sequence is required.

 In the present invention, by incorporating the above-described new operation sequence, a digital camera having a subject identification function that is easy to use and is similar to the operation of a conventional camera, which has not been achieved in a conventional camera having a subject identification function. The purpose is to provide a camera.

  In order to solve the above problems, the invention of claim 1 is directed to an imaging unit that captures a subject image, a first storage unit that stores image data output from the imaging unit at a first time interval, and the first storage unit. Display means for reading and displaying the image data stored in the first storage means at the first time interval; and reading and recording the image data stored in the first storage means at the second time interval. 2 storage means and extraction means for extracting a characteristic part of the subject based on the image data recorded in the second storage means. That is, the image data output from the image pickup means for image display is temporarily stored in the second storage means, and the feature portion is extracted using the stored image data. It is not affected by the update of the storage means.

 According to a second aspect of the present invention, when the image data output from the imaging unit is stored in the first storage unit, the predetermined number of pixels determined by the number of display pixels of the display unit is set. An instruction means for instructing to thin out and record the image data is provided. That is, since the image data stored in the first storage means stores only a small number of image data corresponding to the number of pixels of the display means, the processing on the image data is performed quickly. According to a third aspect of the present invention, when the image data read from the first storage unit is stored in the second storage unit, only a predetermined range of the image data stored in the first storage unit is stored. An instruction means for instructing to store in the second storage means is provided. As a result, the extraction range is further limited, so that the extraction operation can be performed quickly. The invention according to claim 4 is characterized in that the first time interval and the second time interval are equal, and the invention according to claim 5 is characterized in that the first time interval is shorter than the second time interval. It is characterized by that.

 The invention of claim 6 further comprises exposure calculation means for performing exposure calculation at the time of subject photographing, wherein the exposure calculation means performs exposure calculation for the subject corresponding to the characteristic part extracted by the extraction means. It is a feature. The invention according to claim 7 is characterized in that the exposure calculation means performs an exposure calculation on the subject based on image data output from the image sensor after the extraction operation by the extraction means is completed.

 The invention of claim 8 further includes a detecting means for detecting a color condition on the screen to be photographed, wherein the detecting means detects the color condition on the photographing screen after the extraction operation by the extracting means is completed. . The invention according to claim 9 is characterized in that the detecting means detects a color condition in the photographing screen based on image data output from the image sensor after the extraction operation by the extracting means is completed.

 The invention of claim 10 further comprises distance calculating means for calculating the distance to the subject, wherein the distance calculating means calculates the distance to the subject corresponding to the characteristic part extracted by the extracting means. Yes. The invention according to claim 11 is characterized in that the distance calculating means calculates a distance to a subject corresponding to the characteristic part based on image data output from the image sensor after the extraction operation by the extracting means is completed. It is said.

 According to a twelfth aspect of the present invention, an imaging unit that captures a subject image, an extraction unit that extracts a characteristic part of the subject from image data output from the imaging unit at predetermined time intervals, and a distance to the subject are calculated. A distance to the subject is calculated by the distance calculation means after the extraction of the characteristic part of the subject by the extraction means is performed on the image data output from the imaging device in accordance with the operation of the photographer and the photographer And instructing means for instructing to do so. That is, if the photographer performs an operation for starting the extraction of the characteristic part, the extraction operation is performed immediately, and the distance is calculated for the subject extracted after the extraction is completed, so that the distance can be calculated reliably. . The invention of claim 13 is characterized in that the instruction means instructs the distance calculation means to calculate the distance to the subject a plurality of times within the predetermined time interval, and the invention of claim 14 further comprises And an exposure calculation means for performing an exposure calculation when photographing the subject, wherein the instruction means performs an exposure calculation on the subject to the exposure calculation means after the distance calculation means finishes calculating the distance to the subject. The invention of claim 15 further comprises detection for detecting a color condition on a screen to be photographed, and the indicating means is configured to detect the distance after the distance calculating means finishes calculating the distance to the subject. The detection means is instructed to detect a color condition in the photographing screen.

  According to the sixteenth aspect of the present invention, there is provided an extraction unit that extracts a characteristic part of a subject at a predetermined time interval, an exposure calculation unit that performs an exposure calculation at the time of shooting the subject, and an output from the image sensor in response to an operation of the photographer The image processing apparatus includes an instruction unit that instructs the exposure calculation unit to perform an exposure calculation on the subject after the extraction unit extracts the characteristic part of the subject by the extraction unit. That is, if the photographer performs an operation for starting the extraction of the characteristic part, the extraction operation is performed immediately, and the exposure calculation is performed on the extracted subject after the extraction is completed, so that the exposure calculation can be performed reliably.

 The invention according to claim 17 is characterized in that the extraction means for extracting the characteristic part of the subject at predetermined time intervals, the detection means for detecting the color condition in the screen to be photographed, and the image sensor output according to the operation of the photographer An instruction unit is provided for instructing the image data to detect a color condition on the photographing screen after the extraction of the extraction unit is completed. In other words, if the photographer performs an operation for starting the extraction of the characteristic part, the extraction operation is performed immediately, and the color condition is detected for the extracted subject after the extraction is completed. can do.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating the main functions of the digital camera of the present invention. The photographic lens 101 includes a zoom lens for continuously changing the focal length and a focus lens for adjusting the focus. These lenses are driven by a driver 113. Here, the driver 113 includes a zoom driving mechanism and its driving circuit for the zoom lens, and a focus driving mechanism and its driving circuit for the focus lens, which are controlled by the CPU 112, respectively. The photographing lens 101 forms a subject image on the imaging surface of the image sensor 103. The image sensor 103 is a photoelectric conversion image sensor that outputs an electrical signal corresponding to the light intensity of the subject image formed on the image pickup surface, and a CCD type or MOS type solid state image sensor is used. The image sensor 103 is driven by a driver 115 that controls the timing of signal extraction. A diaphragm 102 is provided between the photographing lens 101 and the image sensor 103. The diaphragm 102 is driven by a driver 114 equipped with a diaphragm mechanism and its drive circuit. An imaging signal from the solid-state imaging device 103 is input to the analog signal processing circuit 104, and the analog signal processing circuit 104 performs processing such as correlated double sampling processing (CDS). The imaging signal processed by the analog signal processing circuit 104 is converted from an analog signal to a digital signal by the A / D converter 135.

  The A / D converted signal is subjected to various image processing such as edge enhancement, gamma correction, and white balance correction in the digital signal processing circuit 106. The buffer memory 105 is a frame memory that can store data for a plurality of frames imaged by the image sensor 103, and the A / D converted signal is temporarily stored in the buffer memory 105. The digital signal processing circuit 106 reads the data stored in the buffer memory 105 and performs each process described above, and the processed data is stored in the buffer memory 105 again. The CPU 112 is connected to the digital signal processing circuit 106 and drivers 113 to 115 and performs sequence control when the camera operates. An AE calculation unit 1121 of the CPU 112 performs an exposure calculation based on an image signal from the image sensor, and an AWB calculation unit 1122 performs a calculation for setting a white balance parameter. The feature point extraction calculation unit 1123 stores the feature points such as the shape, position, and size of the subject from the image data in the storage unit 1127 according to a predetermined algorithm, and detects the detected size of the face, eye width, and the like at that time. The approximate distance to each person extracted from the focal length of the zoom lens detected by the detector 121 is also calculated and stored in the storage unit 1125 together with the extraction date and time. Here, the distance calculation method will be described with reference to FIG. FIG. 7 shows a case where the distance to the person is calculated based on the extracted eye width. A is the average value of the actual eye width of a general adult, a is the eye width imaged on the extracted image sensor, L is the distance from the imaging lens to the person, and f is the focal length of the lens. From this figure, the following proportional expression can be easily derived.

A / L = a / f
From here, the distance L to the person is L = (A / a) · f. The storage unit 1125 temporarily stores the feature points extracted in this way and the distance to the feature point calculated based on the feature points. From the stored feature points, the user can select and register the feature points that the user wants to keep.

  The AF method of the digital camera in this embodiment employs a contrast method. This contrast AF will be described here. In this method, there is a correlation between the degree of blurring of the image on the image sensor 103 and the contrast, and focusing is performed using the fact that the contrast of the image is maximized when there is a focus. The magnitude of the contrast can be evaluated by the magnitude of the high-frequency component of the imaging signal. That is, the AF calculation unit 1124 extracts a high-frequency component of the imaging signal by a BPF (bandpass filter) (not shown), and performs AF calculation based on the focus evaluation value using a value obtained by integrating the absolute value as a focus evaluation value. The CPU 112 adjusts the focus lens position of the photographing lens 101 using the calculation result of the AF calculation unit 1124, and performs a focusing operation.

  The operation member 116 connected to the CPU 112 includes a power switch 1161 for turning on / off the camera, a half-press switch 1162 and a full-press switch 1163 that are turned on / off in conjunction with the release button, and a camera displayed on the monitor 109. A setting button 1164 for selecting various menu contents, an up / down (U / D) button 1165 for updating a reproduced image, and the like are provided. The setting button 1164 can select and set alphabets, hiragana, katakana, simple kanji, etc. in combination with the U / D button 1165 in order to name the extracted feature points. In addition, the U / D button 1165 is used to select a desired person from a plurality of extracted persons, or to manually drive the zoom lens to the telephoto or wide side during photographing.

  When the subject brightness is low, the flash 117 is caused to emit light. This strobe is a pre-flash that emits auxiliary light in advance before shooting to prevent red-eye to prevent or reduce the redness of the person's eyes when using the strobe and to measure subject brightness in advance at low brightness It also has functions. In addition to the feature point information described above, the storage unit 1125 also stores the peak value of the evaluation value detected from the AF calculation result, the corresponding lens position, and the like. The image data that has been subjected to various processes by the digital signal processing circuit 106 is temporarily stored in the buffer memory 105 and then recorded on an external storage medium 111 such as a memory card via the recording / reproducing signal processing circuit 110. When recording image data in the storage medium 111, data compression is generally performed in a predetermined compression format, for example, the JPEG method. The recording / reproduction signal processing circuit 110 performs data compression when image data is recorded on the external storage medium 111 and decompression processing of the compressed image data reproduced from the external storage medium 111.

  The monitor 109 is a liquid crystal (LCD) display device for displaying a captured subject image and displaying various setting menus for shooting and reproduction. Here, it is also used when image data recorded in the storage medium 111 is reproduced and displayed. When displaying an image on the monitor 109, the image data stored in the VRAM 107 which is a part of the buffer memory 105 is read out, and the digital image data is converted into an analog video signal by the D / A converter 108. Then, an image is displayed on the monitor 109 using the analog video signal.

  Here, the relationship between the buffer memory 105 and the VRAM 107 when extracting feature points will be described. When image data for display is reproduced on the monitor 109, data obtained by thinning image data for display from image data for still images from the image sensor is continuously output at a constant cycle (for example, 30 frames / second). Is done. The image data is subjected to a predetermined process, and the data is further thinned out so as to have the number of pixels corresponding to the number of vertical and horizontal pixels of the monitor 109 and continuously recorded in the VRAM 107. The data in the VRAM 107 is reproduced as a display image on the monitor 109 through the D / A converter 108. The image data in the VRAM 107 is also used as data for extracting feature points. When extracting feature points, first, image data in the VRAM 107 is recorded again in the buffer memory 105 at a predetermined timing. Here, only a predetermined range (for example, 80% in both the vertical and horizontal directions) of the central portion of the data recorded in the VRAM 107 is recorded in the buffer memory 105. FIG. 6 shows an example of the range in this screen. In FIG. 6, an area indicated by an alternate long and short dash line including three persons on the display screen is a range recorded in the buffer memory 105. It is highly possible that the outer peripheral subject outside this range is not the main subject, and it is meaningless to extract the feature points.To reduce the extraction processing time, the image data excluding the outer subject from the beginning is used. Only for that, the feature point extraction calculation unit 1123 extracts the feature points. Further, when the camera is set to the extraction mode for performing the feature point extraction operation using the setting button 1164 described above, the user is set to the extraction mode by displaying the extractable area in this way. This is preferable because it can be confirmed.

 The reason why the image data is recorded again from the VRAM 107 to the buffer memory 105 in this way is as follows. If the arithmetic processing capability of the CPU 112 is sufficiently high, feature points can be extracted at the rate of 30 frames / second as described above, but the arithmetic capability of the CPU 112 employed in the digital camera is often not so high. Therefore, the feature points can be extracted by re-recording the image data from the VRAM 107 to the buffer memory 105 at a rate suitable for the feature point extraction calculation according to the calculation capability of the CPU 112. In this case, of course, the display update image data is output from the VRAM 105 at a normal rate, so the display update rate does not slow down. Note that the image data for AE calculation and AF calculation is data output from the above-described image sensor 103 and before thinning out to the VRAM 107.

    Next, the timing of feature point extraction (in the figure, a case where face recognition is performed as a feature point), AE, AF, and AWB will be described with reference to FIGS. FIG. 8 shows the case where face recognition is possible from the start of camera operation, and FIG. 9 shows the timing when face recognition is impossible. In both figures, the horizontal axis scale is a time axis based on a cycle (for example, 30 frames / second) read from the image sensor 103, and the face recognition processing is completed within two cycles here. AF calculation and AE calculation, and AF calculation and AWB calculation are performed in series in one cycle.

  In FIG. 8, when the camera operation is started, the aperture is first narrowed down to the minimum aperture, and the focus lens is moved to the position of the hyperfocal distance corresponding to the aperture value. The position of the hyperfocal distance is the closest shooting distance where infinity is within the depth of field of the shooting lens 101. When shooting at this position, everything from 1/2 the hyperfocal distance to infinity enters the depth of field. Details of the initial setting will be described later with reference to FIG. After the initial setting is completed, face recognition calculation is performed from time t1 using data exposed by the image sensor 103.

 When face recognition is possible, AF calculation and AE calculation are performed on a predetermined area including a face recognized using output data thinned out for moving images from the image sensor 103 at time t2. The focus lens is driven based on the AF calculation result. Once focused, the focus lens drive range is limited to a predetermined range before and after the focus position. As a result, even if the subject moves and deviates from the AF area, it is possible to prevent the background from being suddenly in focus. In addition, when there are multiple subjects in the screen and they are moving, the main subject for AF calculation changes one after another as the size and distance of each extracted subject changes, and the focus lens frequently It can be troublesome to move. In order to prevent such a situation, when face recognition is possible, AF calculation may be performed when face recognition becomes impossible without regularly performing AF calculation. In FIG. 8, the AF calculation is shown in parentheses, which indicates that the AF calculation may not be performed in this way. Subsequent to the AF calculation, the AE calculation is performed, and this time, the AF calculation and the AWB calculation are performed using the output from the image sensor 103 at time t3 after the AE calculation ends. The AF calculation is performed as necessary as in the previous cycle. The face recognition calculation is performed from time t4, and thereafter, the same cycle as the cycle from t1 is repeated.

  Next, the case where face recognition is impossible will be described with reference to FIG. The contents from the initial setting to the face recognition end time t2 are the same as those in FIG. When face recognition is impossible, there is no restriction on the movement range of the focus lens with respect to the result of AF calculation started from time t2. Subsequent to the AF calculation, AE calculation is performed. The cycle from time t3 to time t5 is the same as the cycle from time t1 to time t3. The reason why the same operation is repeated in this manner is that the focus lens is moved based on the result of the AF calculation performed between time t2 and time t3, and exposure is performed by the image sensor 103 between time t4 and time t5 after the movement is completed. This is because the processed image data is used for face recognition processing from time t5. If face recognition is still impossible even in the image data after moving the focus lens in this way, the shooting mode set by the camera is determined at time t6. Details of this shooting mode will be described later.

 If the shooting mode is set with emphasis on the person, the focus lens is moved to the above-described position of the hyperfocal distance. On the other hand, when the shooting mode is set with an emphasis on landscape, AF calculation is performed in the same manner as the AF calculation performed at t2 or t4, and the focus lens is moved to the in-focus position based on the result. In the cycle from the time t7 when the AE calculation is completed, the focus lens position is fixed at a predetermined position as it is in the shooting mode with emphasis on the person, while in the shooting mode with emphasis on the landscape. A new AF operation is performed. After that, when the AWB calculation is completed, face recognition calculation is performed at time t8, and thereafter the processing from time t5 is repeated. When face recognition becomes possible due to the movement of the subject on the way, the processing after time t2 in FIG. 8 is repeated. Conversely, when face recognition becomes impossible due to the movement of the subject during extraction, the processing after time t2 in FIG. 9 is repeated. In the description of FIG. 9 so far, the AWB calculation started in the cycle from the time t7. Of course, this is the cycle from the time t3 and the time t5 after the end of the AE calculation as in the case of FIG. May also be performed.

  2 to 5 summarize the series of operation sequences described in FIGS. 8 and 9 in flowcharts. In FIG. 2, first, when it is detected in step S101 that the power of the digital camera is turned on by turning on the power SW 1161, it is determined whether or not the operation mode of the digital camera is set to the face recognition mode in step S102. The face recognition mode can be set using, for example, the setting button S1164. As described above, when the face recognition mode is set, the recognizable area indicated by the alternate long and short dash line is displayed on the LCD monitor 109 as shown in FIG. If the face recognition mode is not set, the process proceeds to step S103, and AF, AE, and AWB operations are performed according to a predetermined sequence in order to perform a normal photographing operation. If the face recognition mode has been set in step S102, the process proceeds to step S104 to perform initial setting for performing face recognition processing. A specific example of this initial setting will be described later with reference to FIG.

  When the initial setting is completed, the feature point extraction calculation unit 1123 extracts the feature point of the subject using the image data exposed after the initial setting is completed in step S105. In step S106, the CPU 112 determines whether or not a person's face can be recognized from the extracted feature points. If face recognition is impossible, the process proceeds to step S107. If face recognition is possible, the process proceeds to step S108. In step S108, subject lock is set for the main subject once set by the photographer. This is to make it easier to follow and shoot the subject after that. The subject lock setting will be described in detail with reference to FIG.

In step S109, it is determined whether it is necessary to perform AF on the locked subject. In a normal case where face recognition is not performed, AF calculation is performed before AE calculation or AWB calculation. However, as described with reference to FIG. 8, the fact that face recognition is being performed means that the focus lens is close to the in-focus position or in-focus. Since it is in the position, it is not always necessary to perform AF calculation before AE or AWB, and it is sufficient to perform AF calculation about once every two to three AE calculation and AWB calculation cycles. Alternatively, if the above-described focus evaluation value is less than or equal to a predetermined value regardless of the number of cycles, AF calculation may be performed assuming that the deviation from the focus is large. For this reason, if AF is not necessary, the process proceeds to step S111. If AF is necessary, the process proceeds to step S110, and the focus lens moving range is limited and AF is performed. This is based on the assumption that even if the main subject moves, it will not move significantly from the current position. By limiting the movement range of the focus lens in this way, if the main subject moves and deviates from the AF area, the focus lens is prevented from moving excessively in an attempt to focus on the background according to the AF calculation result. be able to. When the AF calculation is completed, next, AE calculation is performed in step S111, then auto white balance calculation is performed in step S112, and the process proceeds to step S118 in FIG. As described with reference to FIG. 8, AF calculation may be performed before the AWB calculation in step S112. If it is determined in step S106 that face recognition is impossible, the process proceeds to step S107. Here, it is determined whether or not the focus lens has been moved after it is determined that face recognition is impossible. That is, it is determined whether or not it is determined in step S106 that face recognition is impossible after the focus lens is moved. If the focus lens has not yet been moved, the process proceeds to step S113 to perform AF calculation, and then performs AE calculation in step S114 and proceeds to step 118 in FIG. If it is determined that the face cannot be recognized again after moving the focus lens, the process proceeds to step S115, where the shooting mode set in the digital camera is determined. The shooting mode here refers to a shooting mode that emphasizes people such as portrait mode and commemorative photo mode, or a shooting mode that emphasizes landscape such as landscape mode and night view mode, and any of these shooting modes can be set. It is determined whether it is done. This setting is set by the photographer operating the setting button 1164 while looking at the menu displayed on the monitor 109.

 If the shooting mode is set to emphasize the person, the process proceeds to step S116. If the shooting mode is set to focus on the landscape, the process proceeds to step S111. The reason why face recognition is not possible in this way despite the fact that the person-oriented shooting mode is set is that the person happens to be facing sideways or down, so in step S116 the current position of the focus lens If the focus lens is at the hyperfocal distance position, the process proceeds to step S111. If the focus lens is at the other position, the process proceeds to step S111. move on. Since the position of the hyperfocal distance varies depending on the aperture value of the diaphragm 102 and the focal length of the photographing lens 101, in this step S117, instead of the position of the hyperfocal distance, a fixed position that does not depend on the aperture value (eg, the photographing distance) The focus lens may be moved about 2 m). Also, when it is determined in step S106 that face recognition is impossible, in the above description, the process immediately proceeds to step S107. Instead, the process may return to step S105. That is, it can be considered that it is not sufficient to make a single determination because the subject happens to turn sideways. Therefore, if it is determined that face recognition is impossible, the process returns to step S105 to determine again whether or not recognition is possible, and finally when it is impossible to recognize a predetermined number of times, it is finally determined that recognition is impossible. . Thereby, the accuracy of subject recognition can be improved.

  If it is determined in step S115 that the landscape shooting mode is set, the process proceeds to step S111 with the focus lens position as it is, and AE calculation is performed. Thereafter, AWB calculation is performed in step S112, and then the process proceeds to step S1118 in FIG. In step S118, it is determined whether or not the full press switch 1163 has been pressed. If it has not been pressed, the process returns to step S105 in FIG. 2, and if it has been pressed, the process proceeds to step S119 to photograph the subject. Thereafter, in step S120, it is determined whether the camera is turned off. If not, the process proceeds to step S121, where it is determined whether the face recognition mode has been changed. If the face recognition mode remains set, the process returns to step S105 in FIG. 2, and if the face recognition mode has been changed, the process returns to step 103 in FIG. If the camera is turned off in step S120, the series of shooting operations in the face recognition mode is terminated.

 Next, specific contents of the initial setting will be described with reference to FIG. In this initial setting, the focus lens position and the aperture position are set. First, in step S151, the aperture 102 is set to a preset aperture value. Normally, at the start of camera operation, the aperture 102 is set to the open position or close to the open position. This is to reduce the depth of field so that a specific subject can be easily focused. On the other hand, in the face recognition mode, it is necessary to increase the depth of field so that a wide range of subjects can be recognized. Therefore, the aperture value is set near the minimum aperture diameter or near the minimum aperture diameter. Next, in step S152, the focus lens is moved to the position of the hyperfocal distance described above. In the normal contrast AF operation, when the power is turned on, the focus lens is scanned within a predetermined range to detect the peak of the evaluation value. In contrast, in the face recognition mode, the face recognition operation has priority over the AF operation. For this reason, if the focus lens stops at a close or infinite position for some reason, the person's focus may be greatly out of focus and the face may not be recognized. By moving the focus lens to the position of the hyperfocal distance in this way, it is possible to obtain image data focused on the subject from the beginning of the camera operation, and face recognition can be performed quickly. The position of the hyperfocal distance needs to be calculated based on the focal length or aperture value of the lens. If this is troublesome, the photographing lens may be moved to a predetermined position that does not depend on the lens. Specifically, it is a fixed position within 0.3 to 3 m.

 This completes the initial setting, but in addition to these settings, an AE calculation may be further performed. This is because face recognition becomes impossible if the subject brightness is too bright and the shooting data is skipped, or conversely if the shooting data is crushed because it is too dark. Therefore, before the face recognition operation, the subject brightness is first measured by the AE calculation unit 1121, and the aperture or shutter speed is adjusted so that the subject has a certain level of brightness. Of course, in this initial setting, it is not necessary to perform all the three methods described here, and one of these methods or a combination of several methods may be selected as appropriate.

  Next, details of subject locking in step S108 in FIG. 2 will be described with reference to FIG. In step S201, the recognized subject is identified and displayed by a predetermined display method. FIG. 6 shows an example of this display form. FIG. 6 shows that the face is recognized as a thin solid line or a square display of wavy lines inside the face. Here, the face indicated by the wavy line in the square display indicates that it is the largest face. In addition to this, the approximate distance from the aforementioned eye width to the subject may be obtained, and the face at the shortest distance may be identified and displayed from the result. The setting button 1164 is used to set whether to identify and display the largest face or the nearest face.

 In step S202, it is determined whether the photographer has selected a desired subject. For this selection, the U / D button 1165 is used. If not selected, the process returns to step S201, and if selected, the thin solid line display of the face of the subject selected in step S203 becomes a wavy line display. In step S204, it is determined whether or not the selected subject is locked. Specifically, after the photographer selects a subject, the selected subject is set to a locked state by pressing a setting button 1164. As a result, the selected subject is always set as the AF area or AE area, and even if the locked subject moves and another subject becomes closer or larger, the subject other than the locked subject is moved to the AF area or AE. The area is prevented from moving.

 If not locked, the process returns to step S202 to repeat subject selection. When the locking is completed, the fact that the object is locked in step S205 is displayed in a bold solid line to identify that it is locked. In step S206, it is determined whether or not the set lock has been released. The lock release is released by pressing the setting button 1164 again. As a result, the thick solid line display is changed to a wavy line display to indicate that the lock is released. If the lock is released, the process returns to step S202. If the lock is not released, the subject locking process is terminated. In this example, the object identification symbol is displayed as a square solid line, a wavy line, or a thick solid line. However, this may be displayed in a different color such as red or blue, or the shape may be changed such as a square, triangle, or circle. You may distinguish a lock | rock subject by showing with an arrow.

It is a block diagram which shows the structure of the digital camera by this invention. 5 is a flowchart illustrating an operation sequence of the digital camera according to the present invention. 5 is a flowchart illustrating an operation sequence of the digital camera according to the present invention. It is a flowchart explaining the sequence of initial setting. It is a flowchart explaining a subject locking sequence. It is a flowchart explaining the sequence at the time of setting imaging conditions. It is explanatory drawing which calculates | requires the distance from the focal distance of a lens, and an eye width to a person. It is a figure explaining operation of AF, AE, and AWB when face recognition is possible. It is a figure explaining operation of AF, AE, and AWB when face recognition is impossible.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Shooting lens 102 Diaphragm 103 Image pick-up element 104 Analog signal processing part 105 Buffer memory 106 Digital signal processing part 108 D / A converter 109 LCD monitor 110 Recording / reproduction | regeneration signal processing part 111 External storage medium 112 CPU
DESCRIPTION OF SYMBOLS 113 Lens drive part 114 Aperture drive part 115 Image pick-up element drive part 116 Operation member 117 Strobe 121 Lens position detection part 135 A / D converter 1121 AE calculation part 1122 AWB calculation part 1123 Feature point extraction calculation part 1124 AF calculation part 1125 Storage part 1161 Power switch 1162 Half-press switch 1163 Full-press switch 1164 Setting button 1165 Up / down button

Claims (2)

Imaging means for capturing a subject image;
Image output means for continuously outputting image data thinned out from the image data for still images taken by the imaging means to the image data for display from the imaging means at a constant period;
Image recording means for performing predetermined processing on the thinned image data and further thinning and recording the image data;
Display means for reading out and displaying image data recorded in the image recording means;
A digital camera comprising: extraction means for extracting a characteristic part of the subject based on image data recorded in the image recording means . 2. The digital camera according to claim 1, wherein the image output means outputs the image data from the image pickup means continuously at a cycle of 30 frames / second.