Method for correcting response inconsistency of linear array CCD (Charge Coupled Device) image elements
A correction method and consistent technology, applied in electrical components, image communication, television, etc., can solve the problems of poor correction effect, residual dark current noise, and no consideration of A/D conversion chips, etc., to achieve high correction accuracy and improve signal quality. The effect of the noise ratio
Inactive Publication Date: 2013-05-01
BEIJING RES INST OF SPATIAL MECHANICAL & ELECTRICAL TECH
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Problems solved by technology
The traditional two-point calibration method only uses two sets of calibration coefficients to complete the inconsistency correction (including dark current noise and its inconsistency correction and photoelectric response inconsistency correction), and does not consider the influence of the gain of the A / D conversion chip on the calibration results. Therefore, the correction is less effective
In addition, since this method does not use dark pixels in the CCD, some dark current noise remains in the corrected image
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[0081] The method of the present invention is realized by FPGA, and tested on a certain imager circuit. The CCD used in the imager is a TDICCD. The typical values of photoelectric response inconsistency and dark current noise inconsistency given in the device manual are both 5%, the maximum value of photoelectric response inconsistency is 10%. In order to evaluate the resulting images simply and objectively, three indicators are used for comparison: the grayscale curve before and after correction, the photon transfer curve, and the signal-to-noise ratio (SNR).
[0082] figure 2 The dark current noise before and after correction under different integral series is given (CCD is imaged in full black condition, and the image after imaging is averaged in the column direction respectively), figure 2 In (a), from top to bottom, there are integral series 5, integral series 4, ..., integral series 1. from figure 2 It can be seen from (b) that the dark current noise of the corre...
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The invention discloses a method for correcting response inconsistency of linear array CCD (Charge Coupled Device) image elements. According to the characteristics of a CCD, the existing two-point flat field correction method is improved based on correct calculation of dark current noise; and based on formation mechanism of response inconsistency of the image elements, an inconsistency correctionmethod is divided into two independent parts (dark current noise and inconsistency correction and photoelectric response inconsistency correction), and digital gain correction is also introduced, finally, the correction of response inconsistency of the linear array CCD image elements is implemented. The method provided by the invention can be used for overcoming the defect that, in a two-point correction method, values of dark image elements cannot correctly reflect present dark current noise when the CCD is partially saturated; and the method can be widely used in the present imaging devices, has the characteristics of being easy to realize and high in precision, and can be used for eliminating image degradation caused by dark current noise and image element response inconsistency noise and improving the imaging performance of a detector.
Description
technical field [0001] The invention relates to a method for correcting the inconsistency of the response of linear array CCD pixels. Background technique [0002] Charge-coupled device (Charge-Coupled Devices), referred to as CCD, is a semiconductor imaging device based on the principle of photoelectric conversion. The CCD is the core imaging device of the current imaging system. It can collect the charges generated by the incident photons into its potential well, and output the collected charges in the form of charge transfer through the control circuit, thereby forming a digital image corresponding to the optical image. image. The output signal of CCD contains various noises, such as photon shot noise, dark current noise, fixed pattern noise and readout noise, etc. The existence of these noises seriously affects the detection sensitivity and spatial resolution of the remote sensor. Therefore, suppressing or eliminating image noise is an effective means to improve the im...
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IPC IPC(8): H04N5/361H04N5/365
Inventor 雷宁李春梅李涛王琨
Owner BEIJING RES INST OF SPATIAL MECHANICAL & ELECTRICAL TECH