Autofocus Method Based on Calibration Information

An automatic focus and focus position technology, applied in image communication, color TV parts, TV system parts and other directions, can solve the problems of increasing algorithm calculation amount, difficult to grasp, algorithm falling into local extreme value, etc., to achieve efficiency and Improved stability, reduced focus times, and highly adaptive effects

Active Publication Date: 2021-08-31
江苏骠马智能工业设计研究有限公司
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Problems solved by technology

[0037] 1) The selection of the initial large step size is generally tested or roughly estimated, and it is not easy to grasp. If the initial step size is too small, the search efficiency will be reduced, and if the initial step size is too large, the near-focus area will be skipped, resulting in failure to focus
[0038] 2) A single detection of the falling edge is to reverse the direction, which is susceptible to noise interference, causing the algorithm to fall into a local extremum or turn back at a position deviated from the maximum value, and the focusing effect is not ideal
The existing improved hill-climbing method judges the turn-back with multiple (3 or more) falling edges in a row, which can reduce the interference of noise, but will greatly increase the calculation amount of the algorithm

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  • Autofocus Method Based on Calibration Information
  • Autofocus Method Based on Calibration Information
  • Autofocus Method Based on Calibration Information

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Embodiment Construction

[0064] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

[0065] Such as figure 1 An automatic focusing method based on calibration information shown includes two steps of imaging system calibration and fast search focusing. When the camera, lens, light source and other hardware of the imaging system remain unchanged, the imaging system only needs to be calibrated once. The above calibration information can be used to adaptively generate focus search starting point, step size, threshold and other parameters for the defocus caused by each change of field of view for fast search and focus. The calibration plate is selected to be a plate close to the material of the object to be photographed.

[0066] Su...

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Abstract

The invention relates to an automatic focusing method based on calibration information, which includes two steps of imaging system calibration and fast search focusing; Realize Gaussian fitting with position information; fast search focus is to carry out image analysis in the far focus area and near focus area, perform Gaussian fit on image clarity and position information, and use the fitted position as the focus position. The present invention analyzes and quantifies the invariant characteristics in the hardware through the calibration of the imaging system, and the follow-up search focusing strategy has a rigorous planning on the whole, and the efficiency and stability are greatly improved; the automatic focusing method proposed by the present invention is unimodal Good performance, high timeliness, strong adaptability, and greatly reduce the number of focusing times, only need to collect 5-6 points in the near focus area to achieve σ / 8 high-precision focusing.

Description

Technical field: [0001] The invention belongs to the technical field of automatic focusing of cameras, and in particular relates to an automatic focusing method for quickly searching a current field of view based on the advance calibration of an imaging system. Background technique: [0002] The camera's auto-focus technology is widely used in industrial testing equipment, measurement photography, medical imaging equipment and other fields. The methods of automatic focusing can be mainly divided into two categories: active measurement focusing methods and focusing methods based on image definition. [0003] The active measurement focusing method refers to adding a measurement device outside the imaging system, or embedding the newly added measurement device into the imaging system structurally. The measuring device used in the active measurement focusing method measures the distance of the detected object. When the distance measurement value exceeds the depth of field allow...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N5/232G06T7/80
CPCG06T7/80H04N23/67
Inventor 曹文周永罗华东吴昊季松林
Owner 江苏骠马智能工业设计研究有限公司
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