Patent
Distortion-adaptive visual frequency weighting
Wenjun Zeng,Lei Shawmin +1 more
TLDR
In this paper, a method of quantizing image data including the step of varying the magnitude of a quantization step as a function of the distortion of an image is disclosed for further visually optimizing image quantization.Abstract:
The ability of the visual system to detect contrast in an image is a function of the frequency of the contrasting pattern and the distortion of the image. The visual system is more sensitive to contrasting patterns of lower frequency. When the image is significantly distorted, the visual system is even more sensitive to lower frequencies than higher frequencies. An image encoder employs lossy data compression processes producing a distorted reconstructed image. A method of quantizing image data including the step of varying the magnitude of a quantization step as a function of the distortion of an image is disclosed for further visually optimizing image quantization. Another method utilizes distortion adaptive weighting to vary the limit of code block truncation during embedded bitstream coding to visually optimize image compression by increasing relative lossiness of compression at higher frequencies.read more
Citations
More filters
Patent
Adaptive quantization for enhancement layer video coding
TL;DR: In this article, techniques and tools for encoding enhancement layer video with quantization that varies spatially and/or between color channels are presented, along with corresponding decoding technique and tools.
Patent
Quantization adjustment based on texture level
Xiping Zuo,Chih-Lung B. Lin +1 more
TL;DR: In this article, a video encoder identifies a current smooth region of a current picture in a sequence and performs temporal analysis by determining whether a corresponding region in at least one previous and/or future picture is smooth.
Patent
Adjusting quantization to preserve non-zero AC coefficients
TL;DR: In this article, the authors identify a threshold quantization step size such that the identified AC coefficients of each of the plural blocks are nonzero after quantization according to the threshold quantisation step size.
Patent
Data compression and abnormal situation detection in a wireless sensor network
TL;DR: In this paper, a method and system for wireless communication adapted for compressing data prior to its transmission is described, and abnormal situation detection as part of data compression is also encompassed.
Patent
Adaptive video encoding using a perceptual model
TL;DR: In this paper, an adaptive quantization module quantizes a block according to a quantization method adaptively determined based upon a block classification assigned by the region detection module, and a video encoder adaptively determines whether to drop an isolated last transform coefficient based on block classification, and/or applies a dead-zone selected using the block classification.
References
More filters
Journal ArticleDOI
Visibility of wavelet quantization noise
TL;DR: A mathematical model is constructed for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution that allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold.
Patent
Multimedia compression system with adaptive block sizes
TL;DR: In this paper, a multimedia compression system for generating frame rate scalable data in the case of video, and, more generally, universally scalable data is presented, which is scalable across all of the relevant characteristics of the data.
Patent
Reversible wavelet transform and embedded codestream manipulation
TL;DR: In this article, a reversible wavelet filter is used to generate coefficients from input data such as image data and an entropy coder performs entropy coding on the embedded codestream to produce the compressed data stream.
Patent
Multiple description transform coding of images using optimal transforms of arbitrary dimension
Abstract: A multiple description (MD) joint source-channel (JSC) encoder in accordance with the invention encodes n components of an image signal for transmission over m channels of a communication medium. In an illustrative embodiment which uses statistical redundancy between the different descriptions of the image signal, the encoder forms vectors from transform coefficients of the image signal separated both in frequency and in space. The vectors may be formed such that the spatial separation between the transform coefficients is maximized. A correlating transform is then applied, followed by entropy coding, grouping as a function of frequency, and application of a cascade transform. In an illustrative embodiment which uses deterministic redundancy between the different descriptions of the image signal, the encoder may apply a linear transform, followed by quantization, to generate the multiple descriptions of the image signal. For example, vectors may be formed from transform coefficients of the image signal so as to include coefficients of like frequency separated in space. The vectors are expanded by multiplication with a frame operator, and then quantized using a step size which may be a function of frequency.
Proceedings ArticleDOI
Point-wise extended visual masking for JPEG-2000 image compression
TL;DR: This paper presents a point-wise extended visual masking approach that nonlinearly maps the wavelet coefficients to a perceptually uniform domain prior to quantization by taking advantages of both self-contrast masking and neighborhood masking effects, thus achieving very good visual quality.
Related Papers (5)
Context-based adaptive variable length coding for adaptive block transforms
Marta Karczewicz,Justin Ridge +1 more