Screen Content Image Segmentation Using Least Absolute Deviation Fitting

We propose an algorithm for separating the foreground (mainly text and line graphics) from the smoothly varying background in screen content images. The proposed method is designed based on the assumption that the background part of the image is smoothly varying and can be represented by a smooth model (e.g. a linear combination of a few smoothly varying basis functions), while the foreground text and graphics create sharp discontinuity and cannot be modeled by this smooth representation. The algorithm separates the background and foreground using a least absolute deviation method to fit a smooth model to the image pixels. This algorithm has been tested on several images from HEVC standard test sequences for screen content coding, and is shown to have superior performance over other popular methods, such as k-means clustering based segmentation in DjVu and shape primitive extraction and coding (SPEC) algorithm. This background/foreground segmentation can be used in different applications such as: text extraction, separate coding of background and foreground for compression of screen content images and principle line extraction from palmprint.