Exposure convergence method and related image processing device

An image processing device of executing an exposure convergence function, the image processing device comprising:

• a processing module communicated with an image sensor to acquire a detection image captured by the image sensor, the processing module being adapted to acquire an initial intensity of a detection image provided by an image sensor, provide an exposure setting parameter to the image sensor for generating an input image with a first intensity in accordance with an analysis result of the initial intensity, and utilize a gain parameter to adjust the input image for generating an output image with a second intensity, so that the second intensity of a plurality of sequential output images is gradually varied in one direction;
• wherein the first intensity is lower than the intensity corresponding to a target brightness, and the second intensity determined based on the first intensity and the gain parameter is greater than the intensity corresponding to the target brightness, and the exposure setting parameter and the target brightness correspond to the gain parameter.