Method for measuring modulation transfer function of imaging system based on distance weighting

Abstract

The invention discloses a method for measuring the MTF (Modulation Transfer Function) of an imaging system based on distance weighting, which comprises the following steps: (1) an appropriate edge region in an image obtained by shooting is selected, and the image data is linearized by using a photoelectric conversion function of a sensor to obtain an edge image to be measured; (2) in the edge image obtained in the step 1, the edge position of the edge is obtained by finding the median point of the ESF (Edge Spread Function) of each line successively; (3) an edge position function is obtained by carrying out least square fitting on the edge position of the edge obtained in step 2; (4) the distance from each pixel on the image to the edge is calculated, and the ESF with equidistant samplingis obtained according to the distance weighting; (5) derivation is performed on the ESF obtained in step 4 to obtain a LSF (Line Spread Function), and Fourier transform is performed on the LSF to obtain the MTF of the imaging system. The invention realizes MTF measurement of images containing edge regions, and has the advantages of not being limited by edge angles, good noise resistance, accuratecalculation, good stability, etc.

Description

technical field [0001] The invention belongs to the field of imaging system quality evaluation, in particular to a modulation transfer function measurement method for an optical digital imaging system. Background technique [0002] In actual imaging, the image quality is often affected by many aspects: aberration and diffraction effects of the imaging system; resolution, nonlinear response and various noises of the sensor; external jitter and other interference during shooting, etc. For imaging system image quality evaluation, modulation transfer function MTF (Modulation Transfer Function) is an important index. It objectively reflects the attenuation of different spatial frequency signals after passing through the imaging system, represents the transmission characteristics of the imaging system to the input signal during the imaging process, and is one of the indicators commonly used in the world to evaluate the performance of imaging systems. According to the imaging degr...

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Problems solved by technology

[0006] The technical problem solved by the present invention is: Aiming at the inaccurate measurement result of the MTF due to the inaccurate measurement results of the MTF of the digital imaging system by the inclined edge method when measuring the MTF of the digital imaging system, a method for measuring the modulation transfer function of the imaging system based on distance weighting is proposed

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