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Measuring and calculating method for modulation transfer function of satellite-borne camera

A modulation transfer function and spaceborne camera technology, applied in the field of space optics, can solve problems such as parameter model approximation, achieve the effect of improving constraints, improving measurement accuracy, and strengthening engineering application value

Inactive Publication Date: 2014-08-06
CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0005] The present invention provides a modulation transfer function measurement method for space-borne cameras to solve the problem that the existing point light source measurement and calculation modulation transfer function method needs to use parameter model approximation and fitting

Method used

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  • Measuring and calculating method for modulation transfer function of satellite-borne camera
  • Measuring and calculating method for modulation transfer function of satellite-borne camera
  • Measuring and calculating method for modulation transfer function of satellite-borne camera

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specific Embodiment approach 1

[0017] Specific implementation mode 1. Combination Figure 2 to Figure 5 Description of this embodiment, a method for measuring the modulation transfer function of a spaceborne camera, the method is implemented by the following steps:

[0018] Step 1. Before the satellite transits, lay a set of convex mirrors with the same specifications in a scene with a consistent background, and the distance between each pair is not less than six ground pixel intervals. The convex mirrors reflect sunlight to form multiple point light source targets. The ground pixel interval is known, but due to the shape of the satellite orbit, the ground pixel interval may vary within a certain range.

[0019] Step 2: From the images captured by the spaceborne camera, corresponding to each point light source, the image data of the same size is intercepted.

[0020] Step 3: Estimating the background brightness of the scene, and subtracting the value of the background brightness from the image data in Step...

specific Embodiment approach 2

[0043] Specific embodiment two, combine Figure 3 to Figure 5 Illustrate this embodiment, this embodiment is the application of a kind of modulation transfer function measurement method for spaceborne camera described in specific embodiment one to the convex mirror target imaging experiment laid by QuickBirdII, the ground pixel interval of QuickBird can be 0.6m, also can be 0.61-0.72m. The ground pixel interval depends on the pixel size, the focal length of the optical system, and the altitude of the satellite orbit.

[0044] Firstly, the images corresponding to each point light source are intercepted from the captured image, combined with image 3 ,use image 3 The background data in the dotted area in the center calculates the mean value as the background brightness of the whole area, and it is calculated from image 3 Subtract from each point source image of .

[0045] Let λ=0.5 in formula 5, use formula 6 to iterate repeatedly, when the change of h between two adjacent...

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Abstract

The invention provides a measuring and calculating method for a modulation transfer function of a satellite-borne camera, and relates to the technical field of space optics. According to the method,the problem that according to an existing method that a modulation transfer function is measured and calculated through point light sources, a parametric model is needed for approximation and fitting. Firstly, multiple point light source targets are laid before satellite transit, then images corresponding to point light sources are intercepted in captured images, after the background luminance value is removed, a two-dimensional point spread function is directly solved by the adoption of a regularization solving method according to an imaging mathematical model, and finally a modulation transfer function is calculated through the point spread function. The measuring and calculating method is easy to implement, the data processing process is simple, convenient and precise, and the method has a great significance in imaging quality assessment of the satellite-borne camera and has broad application prospects.

Description

technical field [0001] The invention relates to the technical field of space optics, in particular to a method for calculating a point spread function and a modulation transfer function of a spaceborne camera. Background technique [0002] The modulation transfer function of the spaceborne camera is an important indicator for evaluating the quality of the imaging system, which can reflect the clarity of the image to a large extent, so the spaceborne camera has an index requirement for the modulation transfer function, especially the modulation transfer function in Nyquist The value at the frequency. Taking the camera imaging system as a linear shift-invariant system, the point spread function describes the response of the system to the excitation of the point light source, which can characterize the system characteristics. As the normalized modulus of the Fourier transform of the point spread function, the modulation transfer function describes the response of the system to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F19/00G06T7/00
Inventor 郭玲玲任建岳张立国张星祥何斌吴泽鹏
Owner CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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