System and method for processing digital signals of an infrared image

A system for processing digital signals of an infrared image, comprising a field-programmable gate array (FPGA) chip provided on an infrared camera, for processing digital signals of plural-frame infrared images captured by the infrared camera, wherein the FPGA chip comprises:

• an image process module to, in a frame's backward-stroke, perform a differential weight accumulation process on an original column diagram data representing an original column diagram curve distribution of a current frame image, so as to filter overbright or overdark pixels, and output grayscale value data of a last frame image after being processed by the image process module in a last frame's backward-stroke, wherein the differential weight accumulation process on the original column diagram data performed by the image process module comprises:
• finding out a minimum value in those biggest grayscale values whose pixel numbers occupy 2% of a sum of pixels as a maximum grayscale value of the sum of pixels, that is, when accumulating from a pixel point of a biggest grayscale value in the column diagram down to an extent that accumulated pixel numbers occupy 2% of the sum of pixels, the grayscale value at this time is the maximum grayscale value Xmax of the sum of pixels;
• finding out a maximum value in those least grayscale values whose pixel numbers occupy 2% of the sum of pixels as a minimum grayscale value of the sum of pixels, that is, when accumulating from a pixel point of a least grayscale value in the column diagram up to an extent that accumulated pixel numbers occupy 2% of the sum of pixels, the grayscale value at this time is the minimum grayscale value Xmin of the sum of pixels;
• and
• compressing all grayscale values of the pixels larger than Xmax to 255, and all grayscale values of the pixels less than Xmin to 0;
• and
• an image output module connected with the image process module to, in a frame's forward stroke, receive the grayscale value data of the last frame image and perform a grayscale shift process in way of multi-meandering lines on the received grayscale value data, so as to perform different levels of brightness grayscale shift for the grayscale value data on bright or dark side, and output the grayscale value data of the last frame image after being grayscale shifted in way of multi-meandering lines.