Image Filtering in the Compressed Domain
نویسندگان
چکیده
Linear filtering of images is usually performed in the spatial domain using the linear convolution operation. In the case of images stored in the block DCT space, the linear filtering is usually performed on the sub-image obtained by applying an inverse DCT to the block DCT data. However, this results in severe blocking artifacts caused by the boundary conditions of individual blocks as pixel values outside the boundaries of the blocks are assumed to be zeros. To get around this problem, we propose to use the symmetric convolution operation in such a way that the operation becomes equivalent to the linear convolution operation in the spatial domain. This is achieved by operating on larger block sizes in the transform domain. We demonstrate its applications in image sharpening and removal of blocking artifacts directly in the compressed domain.
منابع مشابه
Semantic-Based Image Retrial in the VQ Compressed Domain using Image Annotation Statistical Models
متن کامل
An Adaptive Hierarchical Method Based on Wavelet and Adaptive Filtering for MRI Denoising
MRI is one of the most powerful techniques to study the internal structure of the body. MRI image quality is affected by various noises. Noises in MRI are usually thermal and mainly due to the motion of charged particles in the coil. Noise in MRI images also cause a limitation in the study of visual images as well as computer analysis of the images. In this paper, first, it is proved that proba...
متن کاملSingular Value Decomposition based Steganography Technique for JPEG2000 Compressed Images
In this paper, a steganography technique for JPEG2000 compressed images using singular value decomposition in wavelet transform domain is proposed. In this technique, DWT is applied on the cover image to get wavelet coefficients and SVD is applied on these wavelet coefficients to get the singular values. Then secret data is embedded into these singular values using scaling factor. Different com...
متن کاملEfficient Schemes for Compressed-Domain Image Resizing
Fast schemes for compressed-domain image size change, are proposed. Fast Winograd DCTs are applied to resizing images by a factor of two to one. First, we speed up the DCT domain downsampling scheme which uses the bilinear interpolation. Then, we speed up other image resizing schemes which use DCT lowpass truncated approximations. The schemes proposed here reduce the computational complexities ...
متن کاملOptimized computational Afin image algorithm using combination of update coefficients and wavelet packet conversion
Updating Optimal Coefficients and Selected Observations Affine Projection is an effective way to reduce the computational and power consumption of this algorithm in the application of adaptive filters. On the other hand, the calculation of this algorithm can be reduced by using subbands and applying the concept of filtering the Set-Membership in each subband. Considering these concepts, the fir...
متن کاملLoop-Filtering and Post-Filtering for Low Bit-Rates Moving Picture Coding
The decompressed images from highly compressed data have noticeable image degradations such as blocking artifacts, corner outliers, and ringing noise, because most image coding standards quantize the DCT coefficients of 8×8-pixel blocks independently. A loopfiltering algorithm and a post-filtering algorithm, which can reduce the quantization effects, are described, and the performances of both ...
متن کامل