Abstract: Edge detection plays an important role in digital image processing. Color image is mapped to a quaternion space, and the rotation transformation for color images is made in the quaternion space. The color image’s original component, strength component and color difference component can be obtained by rotation transformation, and the color difference component can be obtained by filtering the original component and the strength component. The LOG operator has better anti-noise performance, so the edge detection for color difference image is made by using the LOG operator, the vector convolution operation in hypercomplex space is changed into a scalar operation, which greatly reduces the computational complexity. Experiments show that the present method is correct.

Key words: color image, quaternion, edge detection, LOG operator, color difference image, rotation transformation