Total Variation 正則化を用いた JPEG 圧縮画像に対するノイズ除去法

抄録

In accordance with the recent improvement in the quality of image displays, digital image compression artifacts are more visible than ever. Moreover, a lot of studies have been done to remove the artifacts such as blocky noise and mosquito noise. Among them, the total variation (TV) regularization approach proposed by Alter is considered to be one of the most successful. In this approach, the TV is regularized under constrained conditions, making it possible to efficiently remove the artifacts included by quantizing DCT coefficients.
In this paper, unlike Alter's approach, an image is decomposed into a structure component and a texture component using the ROF TV regularization, and blocky noise and mosquito noise are moved in the texture component. Then, by filtering it using the deblocking edge filter, blocky noise can be removed. Furthermore, by controlling the selective filters using edge information obtained from the structure component, mosquito noise can be removed. Also, the reconstructed image is obtained to compose a filtered texture component and a structure component. An advantage the proposed method has over Alter's approach is it removes the artifacts without removing small texture signals. The experimental results show that the proposed method produces fine images subjectively and objectively. Also, the proposed method can be applied for not only JPEG-compressed images but also DCT-based compressed images such as MPEG and H.264.