Automatic Indication Recognition of Dual Pointer Meter in Thermo-Hygrometer Calibrator

In order to make the thermo-hygrometer calibrator more intellectualized, an automatic indication recognition algorithm of dual-pointer meter is proposed. Firstly, Hough circle transform algorithm is used to segment the image and intercept the dial; secondly, the color feature of the image is used to detect the datum point and correct the image; then, the image of pointer is extracted by the improved Zhang thinning algorithm and progressive probabilistic Hough transform algorithm; finally, the algorithm is evaluated by the images of meter captured in an experimental platform of the thermo-hygrometer calibrator. The results show that the algorithm proposed in this paper can recognize the indication of the meter with high accuracy and robustness.