A recognition scheme which identifies the digitals of multimeter is designed in order to extract the digital information of the digital image acquired by the industrial camera. Firstly, the scheme based on the VC++ platform preprocesses the collected color image, the process consists of interception of digital area, image graying and smoothing. Then extracts the target edge contour of recognition, the procedure includes an adaptive piecewise linear transformation based on histogram, nonlinear stretching of gray image, Canny algorithm, 5 field direction predictor boundary tracking and breakpoint compensation; Finally, uses the crossing method to realize digital recognition. The experimental result shows that the scheme of recognition effect is good, fast and simple, so as it has high practical value.