TW201711441A - Photographic device capable of restraining an accidental operation by a simple process when automatically calibrating the low resolution of a photographed picture - Google Patents

Abstract

The present invention provides a photographic device which is capable of restraining an accidental operation by a simple process when automatically calibrating the low resolution of a photographed picture, and capable of precisely informing a user of a notice associated with the calibration of the low resolution. The photographic device 1 of the present invention includes: a photographic part 10 which allows the light from a target area to form imaging on a photographic component 14; a picture processing part 21 which processes the output signal of the photographic component 14 and thereby outputs image information; and a memory part 22 which memorize the basic values of parameters indicating the resolution of the photographed picture. The picture processing part 21 acquires the actual values of the said parameters according to the signal inputted by the photographic component 14, has the actual values acquired at a specific timing be the basic values and memorized in the memory part 22, and performs a resolution enhancement process to the photographed picture according to the difference between the actual values and the basic values saved in the memory part 22. Furthermore, the picture processing part 21 outputs the information indicating that the resolution enhancement process has been executed to an output part 26.

Description

Camera

The present invention relates to an image pickup apparatus for photographing a target area, and particularly to an image pickup apparatus for photographing a landscape whose sharpness may be lowered due to rain or fog.

It is known to use a surveillance camera to take pictures of a street or intersection. In such an image pickup apparatus, the captured image is used for, for example, identification of a traffic accident. During the appraisal, it is possible to confirm the condition of the vehicle or pedestrian, or the lighting condition of the lamp. In other words, it can be confirmed which color of the red, blue, and yellow colors are illuminated during the accident.

However, at a street or an intersection, etc., the contrast of the subject may be lowered due to rain or fog. For example, if the intersection is covered by fog, there is a possibility that the condition of the vehicle or pedestrian, or the lighting condition of the signal light cannot be clearly photographed. As a result, the identification of the captured image cannot be performed smoothly.

Further, in the case where the contrast of the subject is lowered due to the occurrence of rain or fog, it is possible to adopt a method of automatically improving the contrast of the captured image by image processing. However, as a result, the viewer who views the captured image may not be able to grasp the actual occurrence of rain or fog at the shooting site and the extent thereof. As a result, there is no way to accurately take action on the shooting scene.

Patent Document 1 below discloses a surveillance camera system including a surveillance camera device and a control device. In the surveillance camera system, the fog or the haze is detected by the control device based on the image captured by the surveillance camera device. The fog or the ray is generated by comparing the pre-shot image with the current image and detecting whether or not the result is white. Again, fog or The intensity of Xia is determined based on whether the level of the lowest brightness of the image in the digital image signal component (black peak level) exceeds a certain threshold. When the fog or the haze is detected in this way, the alarm corresponding to the intensity of the fog or the radiance is output from the control device to the external device. Further, the Xia correction corresponding to the determined intensity of the fog or the radiance is performed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2014-192762

As described above, in the method of Patent Document 1, in order to correct an image, it is necessary to perform processing of two steps of detecting fog or haze and determining the intensity of fog or haze. The determination of the intensity of the fog or the light is performed based on whether the black peak level exceeds a certain threshold value. Therefore, for example, when a scene in which the black peak level of the original image signal is increased is taken as a subject, it is corrected. Causes a malfunction. Moreover, despite the malfunction in the correction, the alarm about the fog or the haze is still performed, and as a result, the false alarm is provided to the user.

In view of the problem, an object of the present invention is to provide an image pickup apparatus capable of suppressing a malfunction in the case of automatically correcting the unsharpness of a captured image by simple processing, and capable of correcting the correction with the unsharpness The notification is accurately presented to the user.

The main aspect of the present invention relates to an image pickup apparatus. An imaging device according to this aspect includes an imaging unit that images light from a target area on an imaging element, and an image processing unit that processes a signal output from the imaging element to output image information, and the memory unit displays a memory representation A reference value of a specific parameter of the sharpness of the image; and an output unit that outputs the information to the outside. Here, the image processing unit inputs the image from the image sensor. Obtaining the measured value of the parameter, and storing the measured value obtained at the specific timing as the reference value in the memory unit, and based on the difference between the actually measured value obtained and the reference value stored in the memory unit, Perform clearing of the captured image. Further, the image processing unit outputs information indicating that the sharpening processing of the captured image has been performed to the output unit.

According to the imaging apparatus of the present aspect, the reference value indicating the parameter of the sharpness of the captured image is set based on the signal input from the imaging element. Therefore, the set reference value corresponds to the scenery of the subject. For example, when an imaging device is provided for imaging an intersection, the reference value corresponds to the scenery of the target area (the layout of the structure, etc.) such as the size of the intersection or the setting status of the number of lights. Further, since the sharpening processing of the captured image is performed based on the difference between the reference value thus set and the actual measured value obtained at the time of imaging, it is possible to appropriately recognize the extent to which the target region of the subject has become unclear. And it can suppress the malfunction of the clearing process. As described above, according to the imaging apparatus of the present aspect, it is possible to suppress a malfunction when the unsharpness of the captured image is automatically corrected.

Further, according to the imaging apparatus of the present aspect, the sharpening processing is appropriately performed based on the difference between the reference value and the actual measured value, and therefore it is not necessary to separately perform a process of detecting whether or not the captured image becomes unclear. Thus, according to the imaging apparatus of the present aspect, the captured image can be sharpened by simple processing.

Further, according to the image pickup apparatus of the present aspect, when the sharpening processing of the captured image has been performed, the information indicating the situation is output from the output unit, and therefore, even if the clear image after the clearing process is performed is displayed, In addition, information indicating that the clearing process has been performed is presented to the user, thereby preventing the user from mistakenly recognizing the situation at the shooting scene. Further, since it is possible to suppress the erroneous operation in the case where the unsharpness of the captured image is automatically corrected as described above, it is possible to more reliably prevent the erroneous operation of outputting the information indicating that the sharpening process has been performed erroneously. Therefore, according to the imaging apparatus of the present aspect, it is possible to more reliably suppress the malfunction in the case where the unsharpness of the captured image is automatically corrected. And the notification corresponding to the correction of the unsharpness can be more accurately presented to the user.

In addition, the "difference between the measured value and the reference value" refers not only to the value obtained by subtracting the reference value from the measured value, but also the ratio of the measured value to the reference value, etc., as long as the measured value is different from the reference value. The value can be any value.

In the imaging device according to the aspect of the invention, the image processing unit is configured to receive an actual value of the parameter obtained based on a signal from the imaging element as the reference value when receiving an input of a setting instruction. And remember in the above memory. In this way, it is possible to smoothly avoid obtaining and setting the reference value at a timing in which the target area is unclear. Therefore, it is possible to more reliably suppress a malfunction in the case where the unsharpness of the captured image is automatically corrected.

In the image pickup apparatus according to the aspect of the invention, the image processing unit changes the content of the information output to the output unit based on a difference between the actual measured value and the reference value. In this way, the user can more accurately grasp the situation at the shooting scene.

In the image pickup apparatus according to the aspect of the invention, the memory unit is configured to store the second reference value in advance separately from the first reference value based on the actually measured value. In this case, the image processing unit may perform the above-described sharpening processing by acquiring the first reference value based on the actual measurement value when a mode in which the first reference value based on the actual measurement value is used is set. When the above mode is not set, the above-described sharpening processing is executed based on the second reference value. In this case, for example, when the mode in which the first reference value is used is not set because the captured image corresponding to the setting of the first reference value cannot be obtained, the second reference value can be used to perform the sharpening. deal with.

In the image pickup apparatus of the present aspect, the image processing unit switches the adjustment value for sharpening the captured image based on the difference between the actually measured value and the reference value. In this case, the adjustment value can be set to a value for gamma correction of the signal output from the imaging element. Thus, by adjusting the value for performing gamma correction, the contrast of the captured image can be smoothly adjusted to be suitable for sharpening by simple processing. status.

Further, in the image pickup apparatus of the present aspect, as the parameter indicating the sharpness of the captured image, for example, the standard deviation of the luminance obtained from the signal of the one image output from the image pickup element can be used. By using the standard deviation of the brightness as described above, it is possible to accurately grasp the unsharpness of the captured image.

As described above, according to the present invention, it is possible to provide an image pickup apparatus capable of suppressing a malfunction in the case of automatically correcting the unsharpness of a captured image by simple processing, and capable of matching the correction of the unsharpness The notification is accurately presented to the user.

The effects and meanings of the present invention can be further clarified by the description of the embodiments shown below. However, the embodiments described below are merely illustrative of the present invention, and the present invention is not limited by the contents described in the following embodiments.

1‧‧‧ camera

2‧‧‧

3‧‧‧ intersection

4 people

5‧‧‧Car

10‧‧‧Photography Department

11‧‧‧ lens

12‧‧‧ aperture

13‧‧‧Filter

14‧‧‧Photographic components

21‧‧‧Image Processing Department

22‧‧‧Memory Department

23‧‧‧Filter Drive Department

24‧‧‧Aperture Drive Department

25‧‧‧ Input Department

26‧‧‧Output Department

101‧‧‧Mosaic Processing Department

102‧‧‧Linear Matrix Processing Department

103‧‧‧Gamma Correction Processing Department

104‧‧‧Y/C separation processing department

105‧‧‧Contour correction processing unit

106‧‧‧Color Correction Processing Department

107, 108‧‧‧ Noise Removal Processing Department

G1‧‧‧ gamma

G2‧‧‧ gamma value

G3‧‧‧ gamma

R1‧‧‧Brightness distribution range

R2‧‧‧Brightness distribution range

R3‧‧‧Brightness distribution range

S101~S118‧‧‧Steps

W‧‧‧Scope

W1‧‧‧ range

W2‧‧‧ range

Fig. 1 is a block diagram showing the configuration of an image pickup apparatus according to an embodiment.

Fig. 2 is a block diagram showing the configuration of an image processing unit in the embodiment.

3(a) to 3(d) are diagrams showing the relationship between the state of the captured image and the histogram of luminance in the embodiment.

4(a) to 4(d) are diagrams for explaining a method of correcting contrast (sharpening processing) of a captured image in the embodiment.

5(a) and 5(b) are diagrams showing changes in the histogram of the luminance when the gamma value of the embodiment is changed.

(a) and (b) of FIG. 6 are diagrams showing a configuration example of a target region when the captured image of the embodiment is clear, but the distribution range of the luminance of the histogram is narrow.

Fig. 7 is a flow chart showing the clearing process of the embodiment.

Fig. 8 is a view showing an example of gamma characteristics used for the sharpening process of the embodiment.

9(a) and 9(b) are diagrams schematically showing the action of the clarification processing of the embodiment.

Fig. 10 (a) is a view schematically showing an example of display of an image after the sharpening process of the embodiment. Fig. 10 (b) is a view schematically showing an example of display of an image after the sharpening process of the modified example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, the present invention is applied to a surveillance camera that photographs an intersection or a street.

FIG. 1 is a view showing the configuration of the image pickup apparatus 1.

The imaging device 1 includes an imaging unit 10, an image processing unit 21, a storage unit 22, a filter driving unit 23, a diaphragm driving unit 24, an input unit 25, and an output unit 26.

The imaging unit 10 includes a lens 11 , a diaphragm 12 , a filter 13 , and an imaging element 14 .

The lens 11 introduces light from the target area to image the image of the target area on the light receiving surface of the image pickup element 14. The aperture 12 restricts light from the outside in such a manner that an appropriate amount of light is incident on the image pickup element 14 in accordance with the intensity of light from the target region. The diaphragm 12 adjusts the aperture value by the diaphragm driving unit 24.

The filter 13 includes an IR (Infrared) cut filter for removing infrared rays, and a dummy glass that transmits infrared rays together with visible light. The filter 13 is positioned by the image processing unit 21 via the filter driving unit 23 to position the IR cut filter and the white glass between the aperture 12 and the imaging element 14. Specifically, in the case where an illuminance of a normal level or more is obtained in the image pickup element 14, an IR cut filter is inserted into the optical path to remove infrared rays. Further, when the illuminance obtained in the image pickup device 14 is low, the white glass is inserted into the optical path, and the infrared ray is also guided to the image pickup device 14 together with the visible light, thereby improving the sensitivity.

The imaging element 14 is a color CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging element 14 can also be a CCD (Charge Coupled Device) image sensor. The imaging element 14 outputs a signal corresponding to the captured image to the map according to the control from the image processing unit 21. Image processing unit 21.

The image processing unit 21 includes an arithmetic processing circuit such as a CPU (Central Processing Unit), and performs image processing based on the program held in the storage unit 22. The memory unit 22 includes a memory medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and is stored by the image processing unit 21 in addition to the program for image processing. It is also used as a work area during processing. A plurality of gamma correction values corresponding to the level of the sharpness of the captured image are held in the memory unit 22. The gamma correction value held in the storage unit 22 will be additionally described with reference to Fig. 8 .

The filter drive unit 23 and the diaphragm drive unit 24 are drives for driving the filter 13 and the diaphragm 12 in accordance with control from the image processing unit 21. The input unit 25 has an input means such as an operation button, and receives an instruction from the user. The output unit 26 outputs the image information processed by the image processing unit 21 to the external device via the output terminal.

FIG. 3 is a functional block diagram of the image processing unit 21.

The image processing unit 21 includes a mosaic processing unit 101, a linear matrix processing unit 102, a gamma correction processing unit 103, a Y/C separation processing unit 104, a contour correction processing unit 105, a chromatic aberration correction processing unit 106, and a noise removal processing unit. 107, 108.

The signal output from the image pickup device 14 of Fig. 1 is input to the mosaic processing unit 101. The mosaic processing unit 101 generates signals of three colors of R, G, and B from signals from the respective pixels. The linear matrix processing unit 102 performs spectral characteristic correction on the signal generated by the mosaic processing unit 101.

The gamma correction processing unit 103 performs gamma correction on the signal on which the spectral characteristic has been corrected. As described above, in the storage unit 22, a plurality of gamma correction values corresponding to the level of the sharpness of the captured image are held. The gamma correction processing unit 103 applies a gamma correction value corresponding to the sharpness of the captured image. The gamma correction processing unit 103 performs gamma correction on the signal from the linear matrix processing unit 102 using the applied gamma correction value.

The Y/C separation processing unit 104 separates the signal subjected to the gamma correction into a luminance signal and Color difference signal. The contour correction processing unit 105 extracts the contour of the subject based on the signal after the mosaic processing, and applies a contour signal to the luminance signal after the Y/C separation. The chromatic aberration correction processing unit 106 performs a correction process of emphasizing a specific color or the like on the color difference signal after the Y/C separation. The noise removal processing units 107 and 108 respectively remove noise that overlaps the luminance signal and the color difference signal after the Y/C separation. The luminance signal and the color difference signal from which the noise has been removed are output to the output portion 26 of FIG. The output unit 26 serially converts the luminance signal and the color difference signal, and outputs the result to the outside.

Next, the sharpening processing of the image processing unit 21 will be described with reference to FIGS. 3(a) to 6(b). Furthermore, for the sake of convenience, the scenery outside the intersection or the street is taken as the subject.

3(a) to 3(d) are diagrams showing an example of the relationship between the state of the captured image and the histogram of luminance in the embodiment. Fig. 3(b) is a histogram of the captured image of Fig. 3(a), and Fig. 3(d) is a histogram of the captured image of Fig. 3(c). Furthermore, Figures 3(a) and (c) are actually color images. That is, the mosaic tiles and dolls in the image come in various colors. Moreover, the captured image of FIG. 3(c) is obtained by inserting a foggy filter into the imaging optical system.

As shown in FIGS. 3(b) and 3(d), even if the subject is the same, the luminance distribution range (R1, R2) on the histogram changes depending on the sharpness of the captured image. Specifically, the distribution range R2 when the captured image is unclear is narrower than the distribution range R1 when the captured image is clear. Thus, the lower the sharpness (contrast) of the captured image, the narrower the distribution range of the luminance. Therefore, the sharpness of the captured image can be detected based on the distribution range of the luminance.

Furthermore, the information for determining the sharpness of the captured image is not limited to the histogram of the brightness. For example, statistics of the auto iris or the like can also be used to determine the sharpness of the captured image.

4(a) to 4(d) are diagrams for explaining a method of correcting the contrast of a captured image (sharpening processing). Figures 4(a) and (c) are histograms shown in Figures 3(b) and (d), respectively, and are shown in Figures 3(a) and (c). The histogram of the captured image corresponds. 4(b) and 4(d) are graphs schematically showing gamma correction values (gamma characteristics) when the histogram of luminance is the case of FIGS. 4(a) and 4(b). In FIGS. 4(a) and 4(b), the horizontal axis is the signal level of the input signal, and the vertical axis is the signal level of the output signal after the gamma correction.

As shown in FIG. 4(a), when the luminance distribution range R1 in the histogram is wide, the gamma correction is performed using the normal gamma correction value shown in FIG. 4(b). On the other hand, as shown in FIG. 4(c), when the luminance distribution range R2 in the histogram is narrow, the gamma correction value for improving the contrast shown in FIG. 4(d) is used for gamma. Corrected.

In the gamma correction value of FIG. 4(d), the input signal whose signal level is lower than the range W is uniformly converted into the output signal of the lowest level. Moreover, the input signal whose signal level is higher than the range W is uniformly converted into the output signal of the highest level. Therefore, the input signal of the gray near the black is uniformly converted into black, and the input signal of the gray near the white is uniformly converted into white. Thereby, the contrast of the image is improved.

5(a) and 5(b) are diagrams showing changes in the histogram of the luminance when the gamma value (gamma characteristic) is changed. In Fig. 5(a), the dotted line is a gamma characteristic used in the usual gamma correction when the gamma value is 0.45, and the case where the sharpness (contrast) of the captured image of the solid line is low is applied. Gamma characteristics. In Fig. 5(a), the vertical axis and the horizontal axis are normalized by 1. Further, in FIG. 5(b), the broken line is a histogram in the case where the gamma characteristic of the dotted line of 0.45 of FIG. 5(a) is applied to a specific captured image, and the solid line is the same shot. A histogram in the case of applying the gamma characteristic of the solid line for low contrast in Fig. 5(a).

As shown in FIG. 5(b), if the gamma correction is performed using the gamma characteristic for low contrast, the histogram of the corrected captured image is significantly larger than the range before the correction. That is, the sharpness (contrast) of the image can be improved by performing gamma correction on the low-contrast captured image with low definition and applying the gamma correction for the low contrast of FIG. 5(a).

As described above, it is possible to improve the captured image by selecting the gamma correction value to be applied. Contrast. The image processing unit 21 of FIG. 1 improves the shooting by changing the gamma value (gamma characteristic) applied to the gamma correction processing unit 103 of FIG. 2 when the resolution (contrast) of the captured image is low. The contrast of the image.

More specifically, the memory unit 22 of FIG. 1 applies a gamma value (gamma characteristic) and a normal gamma value (gamma) when the sharpness of the captured image is low. Characteristics) Memory together. When the resolution (contrast) of the captured image captured by the imaging device 14 is low, the image processing unit 21 selects a gamma value suitable for the sharpness of the captured image from the storage unit 22, and The selected gamma value is applied to the gamma correction processing unit 103 of Fig. 2 . Thereby, the sharpness of the captured image can be improved.

Here, whether or not the sharpness of the captured image is low can be determined based on the histogram of the luminance distribution as shown in FIGS. 3(a) to (d).

However, depending on the captured image, there is a case where the brightness of the histogram is narrowly distributed due to the layout of the subject or the like although the sharpness is not lowered. For example, the histogram of the captured image (actually a color image) shown in Fig. 6(a) is as shown in Fig. 6(b). In the histogram, although the captured image is clear, the luminance distribution range R3 is narrow. In this case, if the gamma value for low contrast is applied, the sharpness of the captured image will decrease.

Therefore, in the present embodiment, processing for suppressing malfunction in the case of automatically correcting an unclear captured image is performed.

FIG. 7 is a flowchart showing the sharpening process performed by the image processing unit 21.

In the flowchart of FIG. 7, as a parameter indicating the sharpness of the captured image, a histogram of luminance (for example, refer to FIGS. 3(b) and (d)) is used. Further, in the memory unit 22 of Fig. 1, in addition to the gamma value G3 applied when the memory is in the normal definition, the two kinds of gamma values G1 applied in the case where the definition is low are also memorized. G2.

Further, in the flowchart of FIG. 7, the mode setting of the sharpening processing can be performed by the user via the input unit 25 shown in FIG. 1 before or after the start of the processing. Here, the reference value of the standard deviation is set according to the captured image obtained by the shooting target area. The mode of σRef is referred to as a preset on mode, and a mode in which the standard deviation σ0 which is commonly held in the memory unit 22 is set as the reference value σRef is referred to as a preset off mode. The standard deviation σ0 is, for example, the standard deviation of the luminance histogram of the captured image obtained by photographing the standard scenery in a clear state.

Referring to Fig. 7, when the imaging device 1 is powered on and the initialization process is completed, the image processing unit 21 starts the imaging operation. In this manner, after the imaging operation is started, the image processing unit 21 determines whether or not it is the output timing of the vertical synchronization signal (Vsync) (S101). When it is the case of the output timing of the vertical synchronizing signal (S101: YES), the image processing unit 21 performs auto iris processing (S102) and automatic white balance processing (S103). Further, the image processing unit 21 calculates the standard deviation σ of the luminance histogram of the captured image based on the signal output from the imaging element 14 (S104).

Then, the image processing unit 21 determines whether or not the mode of the sharpening process set in the image pickup apparatus 1 is the preset ON mode (S105). Here, when the mode of the clearing process is not the preset on-mode (S105: NO), the image processing unit 21 sets the standard deviation σ0 which is pre-stored in the memory unit 22 as the standard deviation. The reference value σRef (S108).

On the other hand, when the mode of the clearing process is the case of the preset ON mode (S105: YES), the image processing unit 21 determines whether the mode of the output timing sharpening processing of the previous vertical synchronizing signal is a preset break. The on mode, that is, whether the mode of the sharpening process is switched from the preset off mode to the preset on mode (S106). Here, when the mode of the output timing sharpening processing of the previous vertical synchronizing signal is the preset off mode (S106: YES), the image processing unit 21 sets the standard deviation σ calculated in step S104 to The reference value σRef is stored in the memory unit 22 in the set reference value σRef (S107).

Moreover, when the mode of clearing the output timing of the previous vertical synchronizing signal is also the case of the preset on mode (S106: NO), that is, when the preset on mode is from the previous continuation, The image processing unit 21 skips step S107 and advances the processing to step S109. In this case, at least the output timing of the previous previous vertical sync signal, The standard deviation σ based on the captured image obtained at the timing is set to the reference value σRef, and the reference value is also valid at the output timing of the current vertical synchronizing signal.

Then, the image processing unit 21 divides the reference value σRef by the standard deviation σ obtained in step S104, and acquires a reference value (S109). The reference value thus calculated is larger as the standard deviation σ obtained in step S104 is smaller than the reference value σRef. That is, the narrower the distribution range of the luminance of the luminance histogram obtained for the captured image and the luminance histogram corresponding to the reference value σRef, the larger the reference value. Therefore, the larger the reference value, the lower the resolution of the captured image obtained this time can be evaluated.

After the reference value is calculated in this way, the image processing unit 21 compares the threshold values Th1 and Th2 (Th1>Th2) set in advance with the reference value (S110, S112). When the reference value is larger than the threshold Th1 (S110: YES), the image processing unit 21 applies the gamma value G1 for low definition stored in the storage unit 22 to the gamma correction processing unit 103 of FIG. 2 ( S111). When the reference value is equal to or smaller than the threshold Th1 and larger than the threshold Th2 (S110: NO, S112: YES), the image processing unit 21 applies the gamma value G2 for low definition stored in the storage unit 22 to FIG. 2 . The gamma correction processing unit 103 (S113). When the reference value is equal to or smaller than the threshold value Th2 (S110: NO, S112: NO), the image processing unit 21 applies the gamma value G3 for normal resolution stored in the storage unit 22 to FIG. The gamma correction processing unit 103 (S114). The gamma correction processing section 103 of Fig. 2 performs gamma correction based on the gamma value thus applied.

Further, when the gamma value G1 or the gamma value G2 is applied to the gamma correction processing unit 103 in step S111 or step S116, the image processing unit 21 sets the alarm output to ON (S115, S116). When the gamma value G3 is applied to the gamma correction processing unit 103 in step S114, the alarm output is set to off (S117). In other words, when the image processing unit 21 corrects the sharpness of the captured image, the alarm output is set to be turned on, and when the corrected image is not corrected for the captured image, the alarm output is set to disconnect. When the alarm output is set to be on, the image processing unit 21 outputs the alarm information to the output unit 26 (see FIG. 1).

Here, the alarm information may be any information as long as it indicates that the resolution of the captured image has been corrected. For example, the alarm information may be audio information or image information for notifying the correction of the sharpness, or may be code information indicating that only the correction of the sharpness has been performed.

Then, the image processing unit 21 determines whether or not the output timing of the vertical synchronization signal is ended (S118). When the output timing of the vertical synchronizing signal ends (S118: YES), the image processing unit 21 returns the processing to step S101, and waits for the output timing of the next vertical synchronizing signal to arrive (S101). Then, when the output timing of the next vertical synchronizing signal comes (S101: YES), the image processing unit 21 executes the processing from S102 onwards again. This processing is repeatedly executed before the power of the image pickup apparatus 1 is blocked.

Fig. 8 is a view schematically showing gamma characteristics of gamma values G1, G2, and G3.

As shown in FIG. 8, the gamma value G2 is set to an output signal that corrects the range W2 of the low-level side of the input signal to a zero level with respect to the gamma value G3, and the input signal is compared with the gamma value G3. The high level side is closer to the maximum level faster. Further, the gamma value G1 is set such that the range W1 on the input side is larger than the range W2 of the gamma value G2, and the high level side of the input signal is closer to the maximum level than the gamma value G2.

By setting the gamma values G1, G2 in this manner, as described with reference to FIGS. 5(a) and (b), the gamma correction is applied using the gamma value G2, and the gamma is applied to the usual gamma value G3. The sharpness (contrast) of the captured image is improved compared to the corrected situation. Further, in the case where the gamma correction is performed using the gamma value G1, the sharpness (contrast) of the captured image is further improved as compared with the case where the gamma correction is performed by applying the gamma value G2.

Therefore, in step S110 of FIG. 7, when it is determined that the reference value is larger than the threshold Th1, that is, the degree of sharpness reduction of the captured image is severe, the gamma value G1 is applied to the gamma correction processing unit 103 (refer to the figure). 2) The gamma correction is performed to effectively clear the captured image. Further, in step S112 of FIG. 7, if it is determined that the reference value is greater than the threshold Th2, that is, the resolution of the captured image is reduced to a moderate degree, by gamma value G2 The gamma correction processing unit 103 performs gamma correction, and can effectively perform sharpening of the captured image without excessively clearing the captured image.

FIG. 9 is a view schematically showing a captured image when the imaging device 1 is placed at an intersection.

Fig. 9(a) shows a state in which the sharpness of the captured image is lowered due to the influence of rain, fog, or the like. In the present embodiment, as described above, an appropriate gamma value is applied in accordance with the magnitude of the reference value, that is, the level at which the sharpness of the captured image is lowered. Therefore, as shown in FIG. 9(b), the sharpness of the captured image can be improved. . Thereby, the user can accurately confirm the status of the number 2, the intersection 3, the person 4, and the car 5 based on the captured image.

FIG. 10(a) is a view schematically showing a display example when the image information output from the image pickup apparatus 1 is displayed.

Further, in the example of Fig. 10(a), with respect to the configuration of Fig. 9(b), the captured image further includes a mark 6 indicating that the captured image has been subjected to sharpening processing. This flag 6 is based on the fact that the alarm information has been output from the output unit 26 in steps S115 and S116 of Fig. 7 . When the alarm information is not output from the output unit 26, the flag 6 is omitted. By the mark 6, the user can know that the displayed image is a sharpened image, and can grasp that the scene is poor in view due to rain or fog.

Further, instead of the mark 6, or in conjunction with the mark 6, it is notified by audio that the captured image has been subjected to sharpening processing. For example, it is also possible to notify that the captured image has been sharpened by a method of sounding an alarm sound or a method of outputting audio that has been subjected to sharpening processing. In addition, it is also possible to notify that the captured image has been sharpened by a method such as operating the indicator light.

<Effects of Embodiments>

According to this embodiment, the following effects can be exhibited.

As shown in steps S104 and S107 of FIG. 7, the reference value indicating the sharpness of the captured image (standard deviation of the luminance histogram) is set based on the signal input from the image pickup device 14. σRef. Therefore, the set reference value σRef becomes a value corresponding to the scenery of the subject. For example, as shown in FIGS. 9(a) and 9(b), when the imaging device 1 is installed to capture the intersection 3, the reference value σRef becomes a target such as the size of the intersection 3 or the setting state of the number 2 The value of the landscape (the layout of the structure, etc.) corresponds to the value of the area. Then, based on the difference between the reference value σRef thus set and the actual measured value (standard deviation σ) obtained at the time of imaging (reference value: σRef/σ), the sharpening processing of the captured image is performed, so that it is possible to accurately It is possible to recognize the degree of unclearness of the target area of the subject, and it is possible to suppress the malfunction of the clearing process. As described above, according to the imaging apparatus 1 of the present embodiment, it is possible to suppress a malfunction when the unsharpness of the captured image is automatically corrected.

Further, according to the imaging device of the present embodiment, the sharpening process is appropriately performed based on the difference between the reference value σRef and the actual measurement value (standard deviation σ) (reference value: σRef/σ). Therefore, it is not necessary to separately detect whether or not the captured image is changed. Unclear treatment. As a result, according to the imaging device 1 of the present embodiment, the captured image can be sharpened by simple processing.

Further, in the case where the image forming apparatus 1 of the present embodiment has performed the process of sharpening the captured image, the information indicating the situation is output from the output unit 26, and therefore, even if the display is clear after the clearing process is performed, The image, for example, as shown in FIG. 10(a), also presents information indicating that the sharpening process has been performed (marker 6) to the user, thereby preventing the user from mistakenly recognizing the situation at the shooting scene. Further, since it is possible to suppress the erroneous operation in the case where the unsharpness of the captured image is automatically corrected as described above, it is possible to more reliably prevent the erroneous operation of outputting the information indicating that the sharpening process has been performed erroneously. According to the imaging device 1 of the present embodiment, it is possible to more reliably suppress a malfunction in the case where the unsharpness of the captured image is automatically corrected, and it is possible to promptly notify the notification corresponding to the correction of the unsharpness. To the user.

Further, the imaging apparatus 1 of the present embodiment is configured such that, as shown in step S105 of FIG. 7, when the user accepts the input of the setting instruction of the preset ON mode via the input unit 25, the image The processing unit 21 will take the signal based on the image from the imaging element 14. The measured value (standard deviation σ) of the obtained parameter is stored in the memory unit 22 as the reference value σRef. Therefore, the user can set the standard deviation σ based on the clear captured image as the reference value σRef by inputting the setting instruction of the preset ON mode due to the timing of the clear target region. Thereby, it is possible to smoothly avoid obtaining and setting the reference value at the timing when the target area is unclear. Thereby, it is possible to more reliably suppress a malfunction when the unsharpness of the captured image is automatically corrected.

Further, in the imaging device 1 of the present embodiment, the common reference value σ0 is previously stored in the storage unit 22 before the reference value σRef based on the actual measurement value (standard deviation σ) is set. Then, as shown in steps S105 to S108 of FIG. 7, the image processing unit 21 obtains the reference value σRef based on the measured value and performs the sharpening process when the preset ON mode is set, and the preset is not set. In the case of the pass mode, the sharpening process is performed based on the common reference value σ0. Therefore, for example, when the camera device 1 is in a cloudy state at the time of activation, etc., since it is not possible to obtain a clear captured image suitable for the setting of the reference value σRef without setting the preset ON mode, it is also possible to use the general The sharpening process is performed with the reference value σ0.

Further, in the image pickup apparatus 1 of the present embodiment, as shown in steps S110 to S114 of FIG. 7, the adjustment values (gamma values G1 to G3) for sharpening the captured image are switched in accordance with the size of the reference value. Therefore, the contrast of the captured image can be smoothly adjusted to a state suitable for sharpening by simple processing.

Further, in the image pickup apparatus 1 of the present embodiment, the luminance standard deviation σ obtained from the signal of one image output from the image sensor 14 is used as a parameter indicating the sharpness of the captured image, and thus the reference is made to FIG. 3 (see FIG. 3). As described in a) and (b), it is possible to accurately grasp the unsharpness of the captured image.

<Modification>

In the above embodiment, the same alarm information is output from the output unit 26 in steps S115 and S116 of Fig. 7, but the content of the alarm information outputted in step S115 may be different from the content of the alarm information outputted in step S116. That is, it can also be based on the measured value (standard deviation) The content of the information output to the output unit 26 is changed by the difference between the σ) and the reference value σRef (reference value). In this case, the display screen of Fig. 10(a) can be changed as shown in Fig. 10(b). That is, the content of the mark 6 can also be made to correspond to the content of the alert information. In FIG. 10(b), the difference (reference value) between the actually measured value (standard deviation σ) and the reference value σRef is large, and the captured image is corrected based on the gamma value G1 by the mark 6. When the captured image is corrected based on the gamma value G2, the content of the mark 6 is changed to "clearing: low". When the captured image is corrected in accordance with the gamma value G3, the mark 6 is omitted.

In this way, the user can more accurately grasp the situation of the shooting scene by prompting the information of the clearing process. Furthermore, in this case, it is also possible to promptly clear the information by means of audio or the like.

Further, in the above-described embodiment, the captured image is sharpened by adjusting the gamma value applied to the gamma correction processing unit 103, but the sharpening processing of the captured image is not limited thereto. For example, in an image pickup apparatus equipped with a sharpening processing engine for sharpening, it is also possible to sharpen a captured image by adjusting a parameter value set in the sharpening processing engine.

Further, in the above embodiment, two gamma values G1 and G2 are prepared for correction of a captured image having a low definition, but the type of gamma value used for the sharpening processing is not limited thereto. For example, in the flowchart of FIG. 7, the threshold value to be compared with the reference value may be set to three or more, and the gamma value for the sharpening process may be set to three or more. In this way, a more accurate and clear processing can be achieved. Alternatively, the threshold value may be set to one and the gamma value may be set to one.

Further, when the gamma value is set to three or more, the content of the alarm information can be changed for each gamma value. Thereby, the content of the mark 6 of FIG. 10(b) can be changed more finely. Thereby, the user can grasp the situation of the shooting scene more accurately.

Further, in the above-described embodiment, the reference value is a ratio of the reference value σRef to the actual measurement value (standard deviation σ), but the reference value is not limited thereto, and it is only that the measured value is different from the reference value. The value can be any value. For example, a value obtained by subtracting the measured value (standard deviation σ) from the reference value σRef may be used as the reference value.

Further, in the above-described embodiment, the variance of the luminance histogram is used as a parameter indicating the sharpness of the captured image, but the parameter indicating the sharpness of the captured image is not limited thereto. Further, the parameter indicating the sharpness of the captured image is not necessarily limited to one type, and two or more parameters may be combined to determine the sharpness of the captured image.

Further, in the above-described embodiment, the update of the value (gamma value) for the sharpening processing is performed in synchronization with the vertical synchronization signal, but the timing at which the update is performed is not limited thereto. For example, the update of the value for the sharpening process may be performed every specific time (for example, several seconds to several tens of seconds), or may be performed at the timing of detecting the weather change according to the date and time and the illuminance.

Further, the block configuration of the imaging device 1 is not limited to the configuration shown in FIG. 1, and various modifications are possible. Further, the image processing unit 21 may be constituted by a hardware (circuit) or may be composed of a soft body. Further, the image pickup apparatus 1 can be used for various purposes in addition to a surveillance camera for photographing streets or intersections.

Further, the embodiments of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

1‧‧‧ camera

10‧‧‧Photography Department

11‧‧‧ lens

12‧‧‧ aperture

13‧‧‧Filter

14‧‧‧Photographic components

21‧‧‧Image Processing Department

22‧‧‧Memory Department

23‧‧‧Filter Drive Department

24‧‧‧Aperture Drive Department

25‧‧‧ Input Department

26‧‧‧Output Department

Claims (8)

An imaging device comprising: an imaging unit that images light from a target area on an imaging element; an image processing unit that processes a signal output from the imaging element to output image information; and a memory unit Memorizing a reference value of a parameter specific to the sharpness of the captured image; and the image processing unit acquires the actual measured value of the parameter based on the signal input from the imaging element, and uses the actual measured value obtained at the specific timing as the above The reference value is stored in the memory unit, and the sharpening processing of the captured image is performed based on the difference between the actually measured value obtained thereafter and the reference value stored in the memory unit, and further, the clearing of the captured image is performed. The information of the processing is output to the above output unit. The imaging device of claim 1, wherein the image processing unit receives the input of the setting instruction, and stores the measured value of the parameter obtained based on the signal from the imaging element as the reference value in the memory. unit. The image pickup device according to claim 1, wherein the image processing unit changes the content of the information output to the output unit based on a difference between the actual measured value and the reference value. The image pickup device according to claim 2, wherein the image processing unit changes the content of the information output to the output unit based on a difference between the actual measured value and the reference value. The image pickup apparatus according to any one of claims 1 to 4, wherein the memory unit is pre-memorized in advance with the first reference value based on the actually measured value. In the case where the mode of using the first reference value based on the actual measurement value is set, the image processing unit acquires the first reference value based on the actual measurement value, and performs the above-described sharpening process, and the mode is not set. In the case, the above-described sharpening processing is executed based on the second reference value described above. The image pickup device according to any one of claims 1 to 4, wherein the image processing unit switches the adjustment value for sharpening the captured image based on a difference between the actually measured value and the reference value. The image pickup device of claim 6, wherein the adjustment value is used to perform a gamma correction on a signal output from the image pickup device. The image pickup apparatus according to any one of claims 1 to 4, wherein said parameter indicating the sharpness of the captured image is a standard deviation of luminance obtained from a signal of one image output from said image pickup element.