We propose an adaptive enhancement algorithm for low-illumination images based on improved multi-scale Retinex with color restoration (MSRCR) to address the problems of low contrast, poor visual quality, and blurred edge information of images under complex illumination conditions in an automotive welding workshop. First, the reciprocal of the just noticeable difference is added to the MSRCR algorithm as an adjustment factor for the illumination component to obtain an image with clear edge information; then, the adaptive contrast enhancement algorithm is utilized to obtain an image with high contrast and high luminance; finally, two images are fused by Laplace pyramid fusion in proportion to the luminance mean value and linearly stretched. This algorithm can effectively solve the color bias problem of the MSRCR algorithm, highlight the detailed information of the edge of the welded stud to be measured, and retain the brightness enhancement effect.