Objective To study the gamut boundary description in the color gamut mapping. Methods A method of non-uniform segmentation with local threshold segmentation was proposed based on the uniform segmentation method. By changing the threshold and segment numbers, the gamut boundary of images of different types could be uniformly described. Results It could use fewer boundary points to describe the gamut boundary, and show better coverage of the gamut surfaces. There was no centralized gamut boundary points around the gamut surfaces. Conclusion Through comparison with the uniform segmentation method, this algorithm could accurately describe the gamut boundary with fewer boundary points and lower segmentation numbers, which is beneficial for developing the image-to-device gamut mapping algorithm.