Segmentation-based document image denoising
In this work, a robust method of document images denoising is presented. The simple idea is combining the NLM filter and a Markovian segmentation into regions. The NLM method filtering allows participation of far, but proper pixels in the denoising process. Although the weights of non-similar (irrelevant) pixels are very small, high number of these pixels results in introduction of blur. In this work we present a new method to select the best candidate pixels based on their similarity. Before performing denoising process, we segment the noisy image into regions where similar pixels belong to a same homogeneous region r. Thus, to denoise a given pixel i, which belong to a region ri, the proposed algorithm looks for the neighbor pixels of i and includes only those belonging to same region ri. This method is tested on real noisy document images with promising results and it presents an improvement comparing to the original NLM.