Removing the blocking artifacts of block-based DCT compressed images

2003 ◽  
Vol 12 (7) ◽  
pp. 838-842 ◽  
Author(s):  
Ying Luo ◽  
R.K. Ward
Keyword(s):  
Blocking Artifacts ◽  
Compressed Images ◽  
Block Based

scholarly journals A Post-Processing Algorithm for Spatial Domain Detection & Removal of Alocking Artifacts

2019 ◽  
Vol 8 (10) ◽  
pp. 2968-2977
Keyword(s):  
Spatial Domain ◽  
Processing Algorithm ◽  
Blocking Artifacts ◽  
Post Processing ◽  
Compressed Images ◽  
Ringing Artifacts ◽  
Initial Stage ◽  
Pixel Value ◽  
Block Based ◽  
Processing Techniques

Block based Discrete Cosine Transform (BDCT) is commonly used to detect and remove blocking artifacts in the compressed images. We proposed spatial domain post processing algorithm with four fold model. In the initial stage, pixel vector (PV) is calculated for horizontal as well as vertical block boundaries, after defining PV calculation of different threshold values is made for extracting blocking artifacts. These thresholds are basically adaptive to the image quality due to strong correlation with the PV. To avoid ringing artifacts across block edges directional filter is proposed. Our research further worked on region classification based upon activity of PV within the blocks. Based upon different PV activity regions separate filters are used to achieve best filtering and finally Symmetrical Pixel Normalization filter (SPN Filter) is used to normalize the values of symmetrical pixel value for better visual performance . Proposed technique various indices like PSNR, MSSIM, GBIM are calculated and compare with different post processing techniques used in literature

Detecting Non-Aligned Double JPEG Compression Based on Amplitude-Angle Feature

2021 ◽  
Vol 17 (4) ◽  
pp. 1-18
Author(s):  
Jinwei Wang ◽  
Wei Huang ◽  
Xiangyang Luo ◽  
Yun-Qing Shi ◽  
Sunil Kr. Jha
Keyword(s):  
Quality Factor ◽  
Color Image ◽  
Binary Classification ◽  
Image Editing ◽  
Blocking Artifacts ◽  
Jpeg Images ◽  
Compressed Images ◽  
Editing Operation ◽  
Double Jpeg Compression ◽  
Extraction Scheme

Due to the popularity of JPEG format images in recent years, JPEG images will inevitably involve image editing operation. Thus, some tramped images will leave tracks of Non-aligned double JPEG ( NA-DJPEG ) compression. By detecting the presence of NA-DJPEG compression, one can verify whether a given JPEG image has been tampered with. However, only few methods can identify NA-DJPEG compressed images in the case that the primary quality factor is greater than the secondary quality factor. To address this challenging task, this article proposes a novel feature extraction scheme based optimized pixel difference ( OPD ), which is a new measure for blocking artifacts. Firstly, three color channels (RGB) of a reconstructed image generated by decompressing a given JPEG color image are mapped into spherical coordinates to calculate amplitude and two angles (azimuth and zenith). Then, 16 histograms of OPD along the horizontal and vertical directions are calculated in the amplitude and two angles, respectively. Finally, a set of features formed by arranging the bin values of these histograms is used for binary classification. Experiments demonstrate the effectiveness of the proposed method, and the results show that it significantly outperforms the existing typical methods in the mentioned task.

Research on Setting Parameter of Deblocking Filter for H.264

2010 ◽  
Vol 20-23 ◽  
pp. 70-75
Author(s):  
Jin Tao Wang ◽  
Yong Quan Lu ◽  
Chu Qiu ◽  
Peng Dong Gao ◽  
Jie Fu ◽  
...  
Keyword(s):  
Video Transmission ◽  
Strength Parameter ◽  
Video Frame ◽  
Parameter Setting ◽  
Blocking Artifacts ◽  
Deblocking Filter ◽  
Statistical Parameters ◽  
Low Bit Rate ◽  
Block Based ◽  
Occurrence Matrix

The emerging coding standard H.264 is mainly intended for video transmission in many areas. Considering the peculiarity of blocking artifacts which results from block based transform using DCT (discrete cosine transform ) that is most popular method for video coding. These blocking which is due to deficiency of correlation between blocks has much troublesome impact at low bit rate encoding. In this paper, we analyzed the performance of common deblocking filter within H.264 standard, investigated the principle of parameter setting for deblocking filter in an open source code(x264). The outputs of deblocking filter depend on the boundary strength parameter “BS” and the gradient of image samples across the boundary [1]. Usually the filter parameters αc and β were specified a default value zero during x264 running, but in fact selecting different values have a significant effect in the view of image quality. The two statistical parameters of Gray Level co-occurrence Matrix (GLCM), energy and entropy, were used to evaluate the texture of each video picture, and then specify appropriate values for the filter parameters αc and β. We may appraise the effect of deblocking in terms of calculating Mean Squared Difference of Slope (MSDS) for each video frame. In the end of this paper, the experimental results show that our approach, comparing with existing deblocking techniques, is one of the significant methods for reducing blocking artifacts.

Blocking artefact detection in block-based DCT compressed images

2011 ◽  
Vol 4 (3) ◽  
pp. 181
Author(s):  
Jagroop Singh ◽  
Sukhwinder Singh ◽  
Dilbag Singh ◽  
Moin Uddin
Keyword(s):  
Compressed Images ◽  
Artefact Detection ◽  
Block Based
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