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Method to measure response curve of image sensor and device

一种响应曲线、测量图像的技术，应用在图像处理领域，能够解决很难满足对齐要求、响应曲线精度影响、计算处理大量的数据、求解过程繁琐等问题

Active Publication Date: 2013-05-08
SPREADTRUM COMM (SHANGHAI) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, these methods perform multiple exposures on the same scene to obtain a series of exposure images. A large number of pixels in the exposure images need to participate in the calculation of the response curve. , the solution process is extremely cumbersome
[0006] In addition, multiple exposures of the same scene require these exposure images to be aligned at the pixel level in order to correctly reflect the correspondence between pixel values ​​and exposure, otherwise the accuracy of the calculated response curve will be affected
Although you can use auxiliary equipment, such as a tripod, etc. when taking pictures, it is still difficult to meet the above pixel-level alignment requirements

Method used

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  • Method to measure response curve of image sensor and device
  • Method to measure response curve of image sensor and device

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Experimental program
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Embodiment 1

[0064] figure 2 It is a schematic flowchart of the method for measuring the response curve of the image sensor provided by the method embodiment of the present invention, and the steps of the method embodiment are described in detail below.

[0065] In step 201, use the image sensor to be tested to perform at least one exposure shooting on a standard grayscale card to obtain a photographed image. The grayscale card has multiple grayscales, and the grayscale of each grayscale block is uniform. The grayscale of different grayscale blocks The captured image includes a plurality of gray-scale image blocks respectively corresponding to the gray-scale blocks.

[0066] Use the image sensor to be tested to perform at least one exposure shooting on the standard grayscale card to obtain a captured image, and each exposure time is recorded as T(j), and J captured images are obtained. At this time, j=1,...,J,J≥ 1.

[0067] A preferred embodiment is to use the image sensor to be tested,...

Embodiment 2

[0092] The standard grayscale card is theoretically neutral and should not present any color. The color components of each pixel in the captured image are completely equal. For example, the three color components of red, gray and blue in the RGB format image are completely equal. However, since the image sensor may respond inconsistently to different colors, the values ​​of the three color components of the same pixel may not be completely equal. Therefore, the response curve of the image sensor measured and obtained according to the method in the first embodiment may not completely and accurately represent the response curve of each color component.

[0093] In the second embodiment, the captured image has multiple color components, and a corresponding response curve can be obtained for each color component.

[0094] Step 301, use the image sensor to be tested to take at least one exposure shot on the standard grayscale card to obtain a shot image, and the shot image has mult...

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Abstract

The invention discloses a method to measure a response curve of an image sensor and a device. The method includes carrying out exposure shooting at least once on a standard gray scale card to obtain a shooting image; calculating relative exposure of each gray scale image block, wherein the relative exposure is product of exposure time used in exposure shooting and the gray level of each gray scale image block; and arranging a reference point based on a pixel value of a pixel in each gray scale image block and the relative exposure in image shooting, and carrying out calculus of interpolation on the reference point to obtain the response curve of the image sensor. According to the method, by means of the reference point, the calculus of interpolation is carried out to avoid solution of an equation set, and calculated amount is reduced. Due to uniformity of the pixel values in the gray scale image blocks, choice for pixels is easy, alignment and calibration for multiple images with different exposure are needless, and utilization of a calibration algorithm is avoided.

Description

technical field [0001] The invention relates to the field of image processing, in particular to a method and device for measuring a response curve of an image sensor. Background technique [0002] The response curve of the digital image sensor reflects the corresponding relationship between the exposure when shooting and the image pixel value output by the image sensor. Generally speaking, there is a non-linear relationship between exposure and image pixel values. refer to figure 1 as shown, figure 1 A schematic diagram of the response curve of the image sensor is shown, wherein the abscissa is the exposure amount, expressed in natural logarithm, and the ordinate is the image pixel value, expressed using 8-bit data, and its value ranges from 0 to 255. Using the image sensor response curve can post-process the image captured by the image sensor, simulating complex exposure effects that cannot be realized in actual shooting, thereby improving image quality, and then extract...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/26H04N17/00
CPCH04N17/002
Inventor 彭晓峰陈远王森林福辉黄玉春
Owner SPREADTRUM COMM (SHANGHAI) CO LTD
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