blocking artifacts

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blocking artifacts

A distortion that appears in compressed video material as abnormally large pixel blocks. Also called "macroblocking," it occurs when the encoder cannot keep up with the allocated bandwidth. It is especially visible with fast motion sequences or quick scene changes.

Video uses lossy compression, and the higher the compression rate, the more content is removed. At decompression, the output of certain decoded blocks makes surrounding pixels appear averaged together and look like larger blocks. As TVs get larger, blocking and other artifacts become more noticeable. See artifact and pixelated.


Before and After
The lines at the edge of the original frame are used to point to the blocking artifacts, which are removed with Algolith's MPEG Noise Reduction system. Both images are enlarged to show details. (Image courtesy of Algolith inc., www.algolith.com)
References in periodicals archive ?
Kim, "Adaptive blocking artifact reduction using wavelet-based block analysis," IEEE Transactions on Consumer Electronics, vol.
To reduce the blocking artifact, LF components are smoothened in the adjacent LF blocks and invalid HF components are discarded.
4-(c), the blocking artifact always happens because of the codec operation which can affect the judgment of HVS to the VQ.
The state-of-art dark channel prior effectively prevents the appearance of color distortion in haze-free region, but also produces blocking artifacts. In order to eliminate the blocking artifacts, guided image filter is employed.
One of the main drawbacks of this method is that it produces blocking artifacts in the image.
In this indirect way, we can get some improvement of rate-distortion performance; however, these features only reveal the varying of local pixel values, which improves the objective quality of reconstructed image but results in poor visual quality, which is shown especially by the occurrence of many blocking artifacts. In view of the above-mentioned, the proper feature is required to guide the adaptive sampling so as to improve the rate-distortion performance as well as guarantee a better visual quality.
Block-based CS (BCS) hybrid coding framework [15-17] solves the problem of high computational complexity of decoding by measuring and recovering nonoverlapping blocks independently, but nonstationary statistics of image could lead to blocking artifacts. Different statistics of block result in different sparsity of block; thus the measurement times of block should be set accordingly.
Furthermore, it is very important to use the median filter in fusion scheme, which can make fused images smooth and reduce blocking artifacts. Combined with all the vectors, the fused image [I.sub.F] is reconstructed via a single stage of SPL iterations.
However, loss of correlation between adjacent blocks during quantization process in compression results in visually disturbing artifacts called blocking artifacts. The latest H.264/AVC incorporates deblocking filter for reduction of blocking artifacts.
The deblocking filter (DF) reduces blocking artifacts in encoded video sequences, and thereby significantly improves the subjective and objective quality of videos.
"Performance & Analysis of Blocking Artifacts Reduction Using Guassian Adaptive Spatial Low Pass Filter", Journal of Theoretical and Applied Information Technology, 68(01): 149-155.
3(a) have fewer blocking artifacts and are more accurate especially at image edges.