"Two-dimensional Terraced Compression method" and its application in contour detection of transmission image

Multispectral transmission imaging provides a possibility for early breast cancer screening. Due to the strong scattering effect of the light source and the absorption characteristics of the material itself, the image signal is weak. The frame accumulation and demodulation technique can improve the accuracy of the image, but it brings a lot of redundant data. This paper proposes the "Two-dimensional Terraced Compression Method" and applies it to detecting heterogeneity contour in transmission images. The experiment is designed to prove its effectiveness. Four kinds of LEDs with different central wavelengths are respectively modulated as the light source to obtain the image sequences, and the Fast Fourier Transform (FFT) and frame accumulation are used to obtain single-wavelength images respectively. The image is first low-pass filtered, then find the gray minimum value in the image, and then find the connected area in the influence domain of the gradient threshold. If the connected area meets the area threshold, it is used as an effective growth point, and the gray value in the connected area is reassigned. Otherwise, mark it as an isolated point, return to find the minimum, and finally implement terraced compression on the image. This method not only reduces the redundancy of gray numbers but also greatly improves the gradient information of the image, and be used as a preprocessing image algorithm-nonlinear filtering also can be used to detect the contour of heterogeneity.