Abstract: Imaging systems may be provided with image sensors having verification circuitry. Verification circuitry may be configured to verify proper operation of the image sensor during operation. Verification circuitry may include one or more switchable voltage contacts configured to generate a voltage drop across a power supply network of a pixel array during verification operations. Verification circuitry may include a controllable voltage supply coupled to the power supply network of the pixel array. Verification image data may be generated by applying the voltage drop or by using the controllable voltage supply to supply a different supply voltage to each row of pixels prior to readout of that row. Verification image data may be read out using the same circuitry that is used to readout imaging data. Based on a comparison of the verification data with a predetermined standard, imaging systems may continue to operate normally or corrective action may be taken.

Abstract: Imaging systems may be provided with image sensors having verification circuitry. Verification circuitry may be configured to continuously or occasionally verify that the image sensor is functioning properly. For example, verification circuitry may be configured to monitor levels of leakage current during standby mode. Verification circuitry may be coupled between a power supply and circuitry that is powered by that power supply. When the imaging system is in standby mode, circuitry associated with the imaging system such as pixel circuitry may draw a standby leakage current. Verification circuitry may be configured to measure the amount of standby leakage current drawn by associated imaging system circuitry. If the measured level of standby leakage current exceeds a maximum acceptable level of standby leakage current, a warning signal may be generated. Standby leakage current levels on multiple power supply lines may be monitored with associated verification circuitry.

Abstract: A resolution test device and a method thereof are provided. The resolution test method is adapted for testing a resolution of a camera device. The resolution test method includes providing a graph to the camera device, capturing a test image shot by the camera device, shifting an analyzing window a specific distance in a first direction from a static area to a first area on the test image, analyzing the first area to generate a first high-pass element, shifting the analyzing window back to the static area, shifting the analyzing window the specific distance in a second direction from the static area to a second area on the test image, analyzing the second area to generate a second high-pass element, generating a third high-pass element according to the first and the second high-pass element, and defining the resolution of the camera device according to the third high-pass element.

Abstract: An improved method for photon transfer curve (PTC) testing in an image sensor is described. A cost and time savings is achieved by reducing the number of frames necessary for measurements to two that are generated by illuminating a first plurality of pixel rows at a first intensity level m1, a second plurality of pixel rows at a second intensity level t2, and so forth up to an nth plurality of pixel rows illuminated at an nth intensity level mn where mn>m2>m1. The resulting image has “n” regions each with a different brightness. The highest intensity level essentially saturates the pixels in the nth region. In one example, a four row exposure and five intensity levels are employed in the illuminator sequence. An intelligent light source is pre-programmable with illumination intensity settings and is synchronized to the image sensor using HSYNC and VSYNC signals, for example.

Abstract: This disclosure describes techniques for initially calibrating an image capture device. According to one aspect, the calibration includes calibrating parameters of an image filter for resolving the captured image. The method includes receiving a captured image of a test target and resolving the captured image using a set of initial parameters. A sharpness index of the resolved image is determined without matching the captured image to the test target. The sharpness index is used to minimize a cost function for determining parameters for use by the image capture device.

Abstract: A method for calibrating a camera network includes generating a projection matrix by each of cameras in respect of a calibration pattern that is disposed at a plurality of different positions in a photography zone. A portion of the projection matrix is produced as a sub-projection matrix. Sub-projection matrixes are arranged widthwise and lengthwise to generate one sub-measurement matrix. A singular value decomposition (SVD) is performed on the sub-measurement matrix to change the sub-measurement matrix into a matrix having a rank of 3 and a SVD is performed on the changed sub-measurement matrix. A rotation value of the calibration pattern, and an internal parameter and a rotation value of each camera are extracted to thereby calibrate the camera network.

Abstract: A calibrating device for calibration of an image measurement system. The calibrating device includes a main body having an upper surface, and a characteristic portion, which serves as a benchmark for calibration and is in the form of a recess formed in the upper surface of the main body, wherein the characteristic portion includes a side surface extending in a direction crossing the upper surface, and a bottom surface extending in a direction crossing the side surface, the bottom surface has an optical reflectance lower than an optical reflectance of the upper surface in relation to light identical to each other. This can provide a calibrating device for calibration of an image measurement system, which can detect the characteristic portion on the calibrating device stably, precisely and independent of the illumination conditions, which is less costly and can be easily handled.

Abstract: An integrated circuit comprises a semiconductor substrate and a color image sensor array on the substrate. The color image sensor array has a first configuration of color pixels for collecting color image data, and at least one crosstalk test pattern on the substrate proximate the color image sensor array. The crosstalk test pattern includes a plurality of color sensing pixels arranged for making color crosstalk measurements. The test pattern configuration is different from the first configuration.

Abstract: Certain embodiments of the present invention provide methods and systems for calibration of an imaging camera or other image acquisition device. Certain embodiments include characterizing a transformation from a coordinate system of an imager to a coordinate system of a first sensor positioned with respect to the imager using a first off-line calibration. Certain embodiments also include characterizing a transformation from a coordinate system of an imaging camera source to a coordinate system of a second sensor positioned with respect to the imaging camera source using a second off-line calibration. Additionally, certain embodiments include quantifying intrinsic parameters of the imaging camera source based on a transformation from the coordinate system of the imager to the coordinate system of the imaging camera source based on the first and second off-line calibrations and information from the first and second sensors and a transmitter positioned with respect to an object being imaged.

Abstract: Appropriate selection of calibration data by shortening process time without wasteful processing is provided. Before measuring a three dimensional point of a target object from a stereo image, the calibration data according to an in-focus position of taking optical systems are applied to the stereo image. To select the calibration data, an object distance is acquired according to parallax obtained from the stereo image being reduced. The object distance is an estimated focusing distance corresponding to the in-focus position. One of the calibration data assigned with a set distance region in which the estimated focusing distance is included is selected. Respective view images are reduced in a range in which it is possible to detect any one of the set distance regions determined for a respective reference focusing distance corresponding to the calibration data.

Abstract: A method for testing an image capturing function of an electronic device includes following blocks. A test program package with an exemplar image is installed in the electronic device. The electronic device is placed on a test fixture used for limiting an image capturing position and an image capturing angle of the electronic device. The electronic device captures an image to be tested by the electronic device. The image to be tested is compared with the exemplar image to determine whether the image capturing function of the electronic device is satisfactory.

Abstract: One example discloses a method for calibrating an imager. A plurality of images of a target, each having an associated integration time, are captured at the imager. A representative digital count is determined for each of the plurality of images. Integration time is represented as a function of digital count from the respective digital counts and integration times associated with the plurality of images. A calibrated integration time is calculated from a target digital count.

Abstract: The invention is discloses a camera lens calibration system and method thereof, which comprise a calibration platform, the calibration platform comprise a calibration structure. A calibration camera lens to be calibrated is placed on the calibration platform. An image testing module is provided for capturing a target pattern from a target pattern display through the calibration camera lens to be calibrated for getting an image pattern. The image testing module provides a contrast parameter computation for calculating the contrast parameter of image pattern and showing results on a display.

Abstract: Methods and systems for detecting and correcting chromatic aberration and purple fringing are disclosed. Chromatic aberration can be addressed by separating an image into color planes and then adjusting these to reduce chromatic aberration by using a specific calibration image (calibration chart) as an empirical method to calibrate the image acquisition device. Purple fringing can be corrected by initially addressing color aberration resulting from the lateral chromatic aberration (LCA). The LCA is first removed and then the correction is extended to purple fringing. A discovery is relied upon that the purple fringing is created in the direction of the chromatic aberration and is more pronounced in the direction of the chromatic aberration.

Abstract: A system for calibrating a vision system of an object. For example, a system for calibrating a surround view system of a vehicle. The system may be configured to capture, via a first and second image sensor, a first and second image of a plurality of objects. Upon capturing such information, the system may be configured to determine a position and orientation of the first and the second image sensor relative to the plurality of objects based on the first and the second captured image. Further, the system may be configured to determine a relative position and orientation between the first and the second image sensor based on a result of the determining a position and orientation of the first and the second image sensor. Also, the system may be configured to determine intrinsic and extrinsic parameters of the first and the second image sensor.

Abstract: The present invention provides a method and system for high dynamic range image measurement which is configured to control the light intensity distribution through an optical modulating switch for adjusting the intensity of the light passing therethrough so as to control the light intensity distribution of the light projecting on an object or of the object light being sensed by a photo detector for preventing the optical sensing signals of the photo detector from over-saturating. After that, the optical sensing signals are compensated according to the optical intensity distribution modulated by the optical modulating switch so as to obtain an image data with high dynamic range.

Abstract: Systems and methods for testing and calibrating camera modules based on a benchmark standard are provided. The systems can include a receptacle for receiving a camera module under test and a spectrometer. The test station can capture a test measurement using the camera module under test while contemporaneously capturing a true measurement using the spectrometer. Using the true measurement, the test station can predict how the benchmark standard would have performed in those conditions and compare that expected performance to the test measurement. Any differences can be stored in memory within the camera module under test for later retrieval to optimize image processing.

Abstract: An alignment apparatus for adjusting an image sensor is provided. The alignment apparatus includes a first stage, a second stage, a positioning aligned unit, and an adjustment unit. The second stage is floatingly disposed on the first stage. The image sensor is adapted to be disposed on the second stage. The positioning aligned unit connected between the first stage and the second stage constrains the second stage on a datum surface above the first stage. The positioning aligned unit coupled to the second stage drives the second stage to rotate along the datum surface.

Abstract: According to one embodiment, a head separation camera apparatus includes an imaging device, a control device and a cable. The control device includes a first controller. The first controller is configured to output the control signal including a selection command to notify a controlled device acting as a control target from one or more controlled devices in the imaging device and control data indicating contents of control of the control target. The imaging device includes a second controller. The second controller is configured to transmit an individual selection command to inform whether or not a device is the control target and the control data to at least the controlled device acting as the control target, based on the selection command.

Abstract: Systems and methods for generating motion corrected tomographic images are provided. A method includes obtaining first images of a region of interest (ROI) to be imaged and associated with a first time, where the first images are associated with different positions and orientations with respect to the ROI. The method also includes defining an active region in the each of the first images and selecting intrinsic features in each of the first images based on the active region. Second, identifying a portion of the intrinsic features temporally and spatially matching intrinsic features in corresponding ones of second images of the ROI associated with a second time prior to the first time and computing three-dimensional (3D) coordinates for the portion of the intrinsic features. Finally, the method includes computing a relative pose for the first images based on the 3D coordinates.

Abstract: The calibration device 1 is set up in a machine tool 50 and provides: a image capture subject material 10 having a calibration pattern 14 that includes one feature point and being attached to the spindle 55, two-dimensional coordinate calculation parts 22, 23 that calculate the two-dimensional coordinates of feature points based on the two-dimensional image data that is created from the images of the calibration pattern 14 that were captured at multiple movement positions of the spindle 55 by the CCD camera 58; a three-dimensional coordinate calculation part 24 that calculates the three-dimensional coordinates of the feature points that correspond to each movement position of the spindle 55; and a parameter calculation part 26 that calculates the intrinsic parameters and extrinsic parameters of the CCD camera 58 based on the two-dimensional coordinates and three-dimensional coordinates at each movement position of the spindle 55.

Abstract: A method of automatically calibrating a visual parameter, such as luminance or contrast, for an imaging device is disclosed. A ratio of visual parameter difference to lens position difference between two predetermined lens positions is pre-determined for a predetermined focal length. A target visual parameter is then obtained according to the pre-determined ratio, a current visual parameter and lens position difference between a current lens position and a target lens position. Finally, the current visual parameter is updated by the target visual parameter in an automatic mode.

Abstract: Double pass back side image (BSI) sensor systems and methods are disclosed. The BSI sensor may include a substrate, pixel reflectors formed on the substrate, and pixel photodiodes fabricated in the substrate, each pixel photodiode positioned over a respective one of the pixel reflectors. Micro-lenses may be formed over each photodiode and an image filter may be formed between the photodiodes and the micro-lenses. The pixels reflectors, photodiodes, micro-lenses, and filter may be formed using CMOS fabrication.

Abstract: This invention concerns the testing of surveillance camera installations. In particular, the invention involves an automatic testing system for surveillance camera installations, and a method for testing. The invention involves receiving test or “probe” images from at least one camera in the installations. Storing a reference image from at least the one camera. Comparison of the probe image with a reference image from the same camera, and production of an output when maintenance is required for that camera. The comparison involves the steps of: Extracting salient features from both the probe and reference images. Calculating matching factors between the salient features extracted from both images. And, computing a decision about whether maintenance is required from the matching factors.

Abstract: A laser profiling calibration system includes a light emitting device, a light-reflecting target, and an optical receiver. The light emitting device is configured to project a light and define a light plane. The light-reflecting target is configured to be positioned at multiple positions within the light plane, and has a plurality of non-reflective regions. The optical receiver is oriented to receive light reflected from the target, and further configured to capture a plurality of images, comprising at least one image at each of the target's multiple positions. The system is configured to use the plurality of images to calibrate the optical receiver within the light plane.

Abstract: Embodiments of the present invention include circuits and methods for calibrating position displacement in a voltage controlled actuator. In one embodiment, a calibration circuit comprises an actuator having a control terminal for receiving a programmable control voltage to set a displacement, a switch that selectively decouples said programmable voltage from said control terminal and couples a reference current to said control terminal when the control terminal is decoupled from said control voltage, a comparator that senses a voltage difference between said control voltage and said control terminal, and a timer coupled to an output of the comparator. The timer measures a time period required to increase the control terminal voltage. The capacitance of the actuator may be determined and used to calibrate the position of the actuator.

Abstract: In one implementation, an image sensor is calibrated by determining a spectral characterization for each image window of an image sensor, correlating the spectral characterization for each image window of the image sensor with a spectral property of a target illuminant, and generating a scale factor for each image window of the image sensor. The scale factor for each image window of the image sensor is generated based on the correlating.

Abstract: An optical testing apparatus can be operated according to a testing method to test quality of an imaging module of an electronic device. The optical testing apparatus includes a projector, a temperature control device, a processor, and a controller. The controller can control the imaging module to capture an image from the projector and transmit the captured image to the processor. The processor processes the captured image to determine the quality of the imaging module.

Abstract: A method of placing a surveillance camera in a known reference orientation as a result of panning and tilting movements includes coupling the camera to a fixed structure such that the camera may perform the panning movements about a first axis and may perform the tilting movements about a plurality of second axes. Each of the second axes is substantially perpendicular to the first axis. An optical emitter is fixedly attached either to the fixed structure or to the camera. An optical receiver is fixedly attached to the other one of the fixed structure and the camera. The tilting and panning movements are performed with the camera until the emitter and receiver are in a predetermined position relative to each other as determined from a signal that is output by the receiver in response to receiving optical energy from the emitter.

Abstract: A method for testing a camera module of an electronic device includes following blocks. An analysis module and a control module are installed in the electronic device. A test fixture is utilized to secure the electronic device. The control module instructs the camera module to capture a video and a photo. The analysis module automatically examines whether the video and the photo fall within predetermined parameters. A system associated with above method for testing the camera module of the electronic device is also disclosed.

Abstract: A wireless data transmitted method is disclosed. Firstly, a carrier block is displayed. Then, color of the displayed carrier block is modulated in accordance with data to be transmitted. The data is transmitted by capturing an image of the displayed carrier block. The captured carrier block is recognized and the color thereof is calibrated. Finally, the transmitted data is obtained by demodulating the color of the captured carrier block.

Abstract: A method for testing a digital camera module reads a digital image from the digital camera module under test, extracts a tricolor coefficient of each pixel of the digital image to form a measurement array, and compares the measurement array with a reference array to find tricolor coefficient differences. The method extracts an edge of the digital image, processes the edge of the digital image using binarization to obtain measurement binary values, and compares the measurement binary values with reference binary values to find binary values differences. The method further compares a count of the tricolor coefficient differences with a first acceptable value, and compares a count of the binary values differences with a second acceptable value to determine quality of the digital camera module.

Abstract: A motionless focus evaluation test station is provided for measuring detector position error of EO sensors that do not possess dynamic focus capability. A positionally-fixed source emits EM radiation that diverges along an optical axis of the test station. Collimating optics collimate the EM radiation and direct it along the optical axis to the EO sensor. A positionally-fixed target is placed in the path of the diverging EM radiation nominally at the focal plane of the collimating optics. The target comprises a limiting aperture that exhibits an induced shift in optical focus at different positions along the aperture such that different positions on the target are imaged to different focal planes at the detector. The detector captures an image of the target that is blurred to either side of the spatial position that is optically conjugate to the actual detector position.

Abstract: A calibration apparatus includes a calibration target such as a checkerboard, a frame configured to hold the checkerboard in place, a rotatable socket connected at one end to the frame, a stand which is connected to another end of the rotatable socket, a height adjusting portion connected at one end to the stand, and a platform connected to another end of the stand. The checkerboard can be tilted and moved to a particular distance and orientation with respect to an image system to be calibrated by the calibration apparatus. A method of identifying outlier images in the camera parameter estimation process, by using estimated 3D positions of the checkerboard compared with ground truth values.

Abstract: Digital miniature cameras and methods to manufacture thereof have been achieved. Said miniature cameras having an adjustable focusing device are intended to be used as a built-in modules in hand-held consumer electronic devices, such as e.g. mobile phones and PDAs. The cameras invented have a very small size and produce high-quality pictures. Glue is used to hold different parts together and to seal the joints. The lens is glued in the final stage of the manufacturing line, thus providing the focus setting and the sealing of the cavity that covers the image sensor. A glob top is used to cover and seal the image processor. Said glob top serves two different purposes, first, to distribute the heat away from the sensor and, second, to lock the frame, together with the lens house, into a printed circuit board. In one embodiment a cavity PCB is used to “bury” the sensor of the camera, thus reducing the overall height required.

Abstract: Methods and systems for analyzing camera lenses and presenting information regarding camera lenses performance are described. An interactive user interface is provided over a network for display on a user terminal by a computer system. A user request is received at the computer system from the user terminal for lens data from a first lens. Lens data, including test data obtained via a first digital image captured using the first lens at the first focal length setting and the first aperture setting is accessed from memory and transmitted to interactive user interface. The interactive user interface is configured to display an identification of the first camera body, an identification of the first lens, the first focal length setting used to capture the image, and the first aperture setting used to capture the image. Using the lens test data, the interactive user interface generates and displays sharpness graph data.

Abstract: The present invention relates to an apparatus for testing a camera module, and more specifically to a camera module test and focus controlling apparatus.

Abstract: An imaging apparatus includes an image pickup device, a device that obtains an image from the image pickup device, a sensor that detects a roll angle of the sensor, wherein the sensor detects a reference roll angle of the sensor when the imaging apparatus is disposed at a predetermined roll angle, a device that calculates a reference roll angle of the image pickup device by using a reference image from the image pickup device when the imaging apparatus is disposed at the predetermined roll angle and a device that corrects a roll angle of the sensor by calculating a relative roll angle from the reference roll angle of the image pickup device and the reference roll angle of the sensor.

Abstract: An image processing system includes a camera, an image processor and a calibration surface including a calibration pattern, comprising plural alternately colored elements which provide a corresponding plurality of corners at locations at which more than two of the colored elements adjoin. The image processor detects from the video signal at least some of the corner locations and identifies a first and second group of lines of the calibration pattern, extrapolate the lines from each group and determine a on a plane of the scene as viewed by the camera, the presence and location of a first and second intersection points on where the extrapolated lines from the first and second groups, respectively, intersect to estimate one or more of a roll pitch and yaw angle of the camera relative to the calibration surface and extimates a likelihood that a corner is located at each of identified potential corner locations.

Abstract: A disclosed calibration apparatus is configured to receive inputs of two reference images and plural items of parallax data, these two reference images being captured by one of the imaging devices at two locations, and the parallax data being calculated using these two reference images and two corresponding images based on positions of plural feature points common to the reference image and the corresponding image for each pair thereof on a location basis, two corresponding images being captured by another of the imaging devices at these two locations; search for plural feature points common to these two reference images; calculate parallaxes and parallax changing amounts, based on the parallax data related to the respective feature points in these two reference images, for each of the searched feature points; and calculate a correction value for the parameter based on the calculated parallaxes and parallax changing amounts.

Abstract: Techniques for modifying data of an image that can be implemented in a digital camera, video image capturing device and other optical systems are provided to correct for non-uniform illumination appearing in data obtained using one or more illumination sources from a two-dimensional photo-sensor. In order to correct for these variations, a small amount of modification data is stored in a small memory within the optical system. According to a specific embodiment, non-uniform illumination correction factors are derived during a calibration procedure by illuminating a surface having uniform optical properties with the non-uniform illumination source and imaging that illuminated surface onto the photo-sensor.

Abstract: An image pickup apparatus includes: a photoelectric transduction portion to transduce an optical image of a subject formed on an image plane through a lens to output an image signal; a movement portion provided between the photoelectric transduction portion and a base to move the photoelectric transduction portion relative to the base; an illumination portion placed at a predetermined position from the base to emit light onto the image plane of the photoelectric transduction portion in a state in which a shutter is closed to block light entering from the lens; a light-blocking portion placed at a predetermined position from the base to interrupt part of light from the illumination portion at between the illumination portion and the image plane; an adjustment image obtaining portion to obtain an image signal output by the photoelectric transduction portion as a result of photoelectric transduction, in a state in which the illumination portion emits light; and a relative position detection portion to detect a r

Abstract: Provided is a calibrating apparatus for an on-board camera of a vehicle, which apparatus allows completion of calibration process with a simple additional calibration, even when rejection has issued on the result of automatic calibration. Based upon a camera parameter obtained at the time of completion of adjustment by an automatic adjusting section, a confirmation marker indicating the position of coordinate of a calibration point is displayed in superposition with a camera-captured image. A manual adjusting section adjusts the camera parameter, based on an amount of displacement of the coordinate of the calibration point corresponding to an amount of movement of the confirmation marker moved in response to input of adjustment instruction.

Abstract: A stereo calibration method is proposed to calibrate an interface's shape and position when the measurement system is in one media and measures deformation and strain of an object that is submerged in a different media. After the interface's shape and position are modeled by parameters, an explicit model of object points as measurement is established taking account of refraction happening at the interface. Efficiency and convergence are assured by using measurement of object points to acquire initial estimates for refraction angles at the interface. Then, an optimization method is performed to get the optimized value of interface parameters. Last, based on the resulting interface parameters, 3-dimensional positions of object points in all the subsequent measurement could be reconstructed accurately. Therefore, the distortion induced by refraction in the measurement is corrected.

Abstract: A method of calibrating, compressing and decompressing image signal values of an image sensor which has a plurality of light sensitive pixels arranged in rows and columns comprises the steps of: reading out the image signal values; compressing the image signal values; and decompressing the compressed image signal values, wherein the image signal values are calibrated while using calibration data sets which include a number of calibration values for each pixel.

Abstract: A camera module includes an image capture unit used to capture at least one image of a subject. An image analysis unit is integrated in the camera module to analyze the quality of the image captured by the image capture unit to determine whether the camera module meets one or more preset requirements. The camera module further includes an output unit used to output one or more analysis results of the image analysis unit to determine whether the camera module meets preset capability requirements.

Abstract: A method is provided for testing a camera function of an electronic device. The electronic device communicates with a testing device. The method comprises the following steps. Parameters are configured by a parameter module of the electronic device. A camera of the electronic device takes pictures according to the configured parameters. The pictures and the configured parameters are sent to the testing device by a sending module of the electronic device. The pictures and the configured parameters are received by a receiving module of the testing device. Parameters of the pictures are got by a judging module of the testing device, and the judging module judges whether the parameters are identical to the configured parameters.

Abstract: A road line recognition apparatus, including: an imaging section imaging a progress path of a own vehicle including a road to output a couple of images; an image processing section calculating a distance in a real space in a set region of at least an image on one side based on the imaged couple of images; and a detection section detecting a road line; wherein the detection section includes: a road line candidate point detection and conversion processing unit detecting a pixel on a road surface as a road line candidate point based on luminance and the distance with regard to the image on one side, and performing Hough conversion of the road line candidate point; a road line straight line detection processing unit detecting one straight line proper to the road line on each of a right side and a left side of the own vehicle based on at least a position or a behavior of the own vehicle between straight lines obtained by the Hough conversion; and a road line detection processing unit detecting the road line of a s

Abstract: A device and technique are presented to calibrate an imaging device for generating three-dimensional surface models of moving objects and calculating three-dimensional coordinates of detected features relative to a coordinate system embedded in the device. The internal projector and camera parameters, i.e., zoom, focus, aperture, optical center, logical pixel size, aspect ratio, are determined for all projectors and cameras and all possible focal planes of the device in operation.

Abstract: In a method for testing an aperture of the image capturing device, a brightness value range of images is divided into a plurality of range intervals, and one of the range intervals is determined for testing the aperture. A brightness value of a current image captured by the image capturing device is calculated. A diameter of the aperture is controlled to increase or decrease to change the brightness value of the current image to be within the determined range interval, if the brightness value is not within the determined range interval. After the brightness of the current is changed to be within the determined range interval, if the brightness value of the current image has been changed during a predetermined time period, it is determined that the aperture does not work normally.