Hydrological sheet color image segmentation based on gradient and color information

This paper proposes a color image segmentation method based on the integration of gradient and color information, which is applied to the digitization of hydrological sheet and the image is captured by an ordinary camera. Firstly, curves are obtained by making use of color information in the Lab color space. Then the image is processed in a block-by-block manner. The gradient operators in horizontal and vertical directions respectively are performed to discriminate the target pixels on the grid lines roughly. Thirdly, the color information of those pixels is obtained and the threshold to segment the grid lines are set. After getting the grid lines, horizontal and vertical erosions are performed respectively and most of the noise is removed. Finally, the segmented curves and the grid lines are merged and the final segmentation is established. The experimental results on several hydrological sheet color images show that our approach can fulfill the goal of image segmentation effectively in a self-adaptation way and alleviate the effect of uneven illumination with good robustness and lower computation complexity.