An Effective Bicubic Convolution Interpolation-Based Iterative Luma Optimization for Enhancing Quality in Chroma Subsampling

10.36227/techrxiv.16544898 ◽

2021 ◽

Author(s):

Kuo-Liang Chung ◽

Chih-Yuan Huang ◽

Chen-Wei Kao

Keyword(s):

Iterative Method ◽

Color Image ◽

State Of The Art ◽

Linear Interpolation ◽

Distortion Function ◽

Full Color ◽

Screen Content ◽

Modification Method ◽

Convex Property

<div>Traditionally, prior to compressing an RGB full-color image, for each converted 2x2 CbCr block BCbCr, chroma subsampling only downsamples BCbCr, but without changing the luma block BY at all. In the current research, a special linear interpolation-based, namely the COPY-based, chroma subsampling-first luma modification (CSFLM) study has attempted to change the luma block for enhancing the quality of the reconstructed RGB full-color image. In this paper, a fast and effective nonlinear interpolation, namely the bicubic convolution interpolation (BCI), based iterative luma modification method for CSFLM is proposed. In our iterative method, a BCI-based distortion function and its convex property proof are first provided. Next, based on the proposed convex distortion function, a pseudoinverse technique is applied to obtain the initial luma modification solution, and then an iterative method is proposed to improve the initial luma modification solution. Based on five testing image datasets, namely the IMAX, Kodak, SCI (screen content images), CI (classical images), and Video datasets, the thorough experimental results have demonstrated that on the newly released Versatile Video Coding (VVC) platform VTM-12.0, our iterative luma modification method achieves substantial quality, execution-time, and quality-bitrate tradeoff improvements when compared with the existing state-of-the-art methods.</div>

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A Coordinate Displacement Compensation Based Quality Enhancement Method for Chroma Subsampling and Upsampling on VVC

10.36227/techrxiv.15178356.v1 ◽

2021 ◽

Author(s):

Kuo-Liang Chung

Keyword(s):

Color Image ◽

Research Direction ◽

Quality Enhancement ◽

Coding System ◽

Server Side ◽

Full Color ◽

Screen Content ◽

Enhancement Method ◽

Client Side

<div>Prior to encoding an input RGB full-color image IRGB, at the server side, performing chroma subsampling on the converted chroma image is a necessary step. After receiving the decompressed subsampled chroma image and luma</div><div>image at the client side, performing chroma upsampling is also a necessary step for reconstructing the RGB full-color image. In this paper, we consider seven commonly used chroma subsampling methods, denoted by Cs, and four widely used chroma upsampling methods, denoted by Cu. For each combination cs-cu in CsxCu, we first utilize the moment balance law to analyze the coordinate displacement (CD) bias problem occurring in cs. Next, for the combination cs-cu, we analyze the CD bias problem occurring in the transition from the server side to the client side. Then, we explain why the CD bias problem degrades the quality of the reconstructed RGB full-color images in the current coding system. To remedy this CD bias problem, a CD compensationbased (CDC-based) quality enhancement method is proposed to improve the quality of the reconstructed images. To the best of our knowledge, this is the first work in this research direction. Based on the IMAX, Kodak, SCI (screen content images), and Video datasets, the comprehensive experimental results have demonstrated that on the newly released versatile video coding (VVC) platform VTM-12.0, the proposed CDC-based quality enhancement method in our augmented coding system can achieve substantial quality improvement for 17 combinations in CsxCu.</div>

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A Coordinate Displacement Compensation Based Quality Enhancement Method for Chroma Subsampling and Upsampling on VVC

10.36227/techrxiv.15178356.v2 ◽

2021 ◽

Author(s):

Kuo-Liang Chung ◽

Chen-Wei Kao

Keyword(s):

Color Image ◽

Research Direction ◽

Quality Enhancement ◽

Coding System ◽

Server Side ◽

Full Color ◽

Screen Content ◽

Enhancement Method ◽

Client Side

<div>Prior to encoding an input RGB full-color image IRGB, at the server side, performing chroma subsampling on the converted chroma image is a necessary step. After receiving the decompressed subsampled chroma image and luma</div><div>image at the client side, performing chroma upsampling is also a necessary step for reconstructing the RGB full-color image. In this paper, we consider seven commonly used chroma subsampling methods, denoted by Cs, and four widely used chroma upsampling methods, denoted by Cu. For each combination cs-cu in CsxCu, we first utilize the moment balance law to analyze the coordinate displacement (CD) bias problem occurring in cs. Next, for the combination cs-cu, we analyze the CD bias problem occurring in the transition from the server side to the client side. Then, we explain why the CD bias problem degrades the quality of the reconstructed RGB full-color images in the current coding system. To remedy this CD bias problem, a CD compensationbased (CDC-based) quality enhancement method is proposed to improve the quality of the reconstructed images. To the best of our knowledge, this is the first work in this research direction. Based on the IMAX, Kodak, SCI (screen content images), and Video datasets, the comprehensive experimental results have demonstrated that on the newly released versatile video coding (VVC) platform VTM-12.0, the proposed CDC-based quality enhancement method in our augmented coding system can achieve substantial quality improvement for 17 combinations in CsxCu.</div>

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The Effect of the Color Filter Array Layout Choice on State-of-the-Art Demosaicing

Sensors ◽

10.3390/s19143215 ◽

2019 ◽

Vol 19 (14) ◽

pp. 3215 ◽

Cited By ~ 2

Author(s):

Ana Stojkovic ◽

Ivana Shopovska ◽

Hiep Luong ◽

Jan Aelterman ◽

Ljubomir Jovanov ◽

...

Keyword(s):

Color Image ◽

State Of The Art ◽

Image Data ◽

Linear Interpolation ◽

Color Filter ◽

Color Filter Array ◽

Full Color ◽

Design Choice ◽

Filter Array ◽

The One

Interpolation from a Color Filter Array (CFA) is the most common method for obtaining full color image data. Its success relies on the smart combination of a CFA and a demosaicing algorithm. Demosaicing on the one hand has been extensively studied. Algorithmic development in the past 20 years ranges from simple linear interpolation to modern neural-network-based (NN) approaches that encode the prior knowledge of millions of training images to fill in missing data in an inconspicious way. CFA design, on the other hand, is less well studied, although still recognized to strongly impact demosaicing performance. This is because demosaicing algorithms are typically limited to one particular CFA pattern, impeding straightforward CFA comparison. This is starting to change with newer classes of demosaicing that may be considered generic or CFA-agnostic. In this study, by comparing performance of two state-of-the-art generic algorithms, we evaluate the potential of modern CFA-demosaicing. We test the hypothesis that, with the increasing power of NN-based demosaicing, the influence of optimal CFA design on system performance decreases. This hypothesis is supported with the experimental results. Such a finding would herald the possibility of relaxing CFA requirements, providing more freedom in the CFA design choice and producing high-quality cameras.

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A Coordinate Displacement Compensation Based Quality Enhancement Method for Chroma Subsampling and Upsampling on VVC

10.36227/techrxiv.15178356 ◽

2021 ◽

Author(s):

Kuo-Liang Chung ◽

Chen-Wei Kao

Keyword(s):

Color Image ◽

Research Direction ◽

Quality Enhancement ◽

Coding System ◽

Server Side ◽

Full Color ◽

Screen Content ◽

Enhancement Method ◽

Client Side

<div>Prior to encoding an input RGB full-color image IRGB, at the server side, performing chroma subsampling on the converted chroma image is a necessary step. After receiving the decompressed subsampled chroma image and luma</div><div>image at the client side, performing chroma upsampling is also a necessary step for reconstructing the RGB full-color image. In this paper, we consider seven commonly used chroma subsampling methods, denoted by Cs, and four widely used chroma upsampling methods, denoted by Cu. For each combination cs-cu in CsxCu, we first utilize the moment balance law to analyze the coordinate displacement (CD) bias problem occurring in cs. Next, for the combination cs-cu, we analyze the CD bias problem occurring in the transition from the server side to the client side. Then, we explain why the CD bias problem degrades the quality of the reconstructed RGB full-color images in the current coding system. To remedy this CD bias problem, a CD compensationbased (CDC-based) quality enhancement method is proposed to improve the quality of the reconstructed images. To the best of our knowledge, this is the first work in this research direction. Based on the IMAX, Kodak, SCI (screen content images), and Video datasets, the comprehensive experimental results have demonstrated that on the newly released versatile video coding (VVC) platform VTM-12.0, the proposed CDC-based quality enhancement method in our augmented coding system can achieve substantial quality improvement for 17 combinations in CsxCu.</div>

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Effective Three-Stage Demosaicking Method for RGBW CFA Images Using The Iterative Error-Compensation Based Approach

Sensors ◽

10.3390/s20143908 ◽

2020 ◽

Vol 20 (14) ◽

pp. 3908

Author(s):

Kuo-Liang Chung ◽

Tzu-Hsien Chan ◽

Szu-Ni Chen

Keyword(s):

Error Compensation ◽

Color Image ◽

Ground Truth ◽

Input Image ◽

Previous Method ◽

Color Filter ◽

Second Stage ◽

Full Color ◽

Iterative Error

As the color filter array (CFA)2.0, the RGBW CFA pattern, in which each CFA pixel contains only one R, G, B, or W color value, provides more luminance information than the Bayer CFA pattern. Demosaicking RGBW CFA images I R G B W is necessary in order to provide high-quality RGB full-color images as the target images for human perception. In this letter, we propose a three-stage demosaicking method for I R G B W . In the first-stage, a cross shape-based color difference approach is proposed in order to interpolate the missing W color pixels in the W color plane of I R G B W . In the second stage, an iterative error compensation-based demosaicking process is proposed to improve the quality of the demosaiced RGB full-color image. In the third stage, taking the input image I R G B W as the ground truth RGBW CFA image, an I R G B W -based refinement process is proposed to refine the quality of the demosaiced image obtained by the second stage. Based on the testing RGBW images that were collected from the Kodak and IMAX datasets, the comprehensive experimental results illustrated that the proposed three-stage demosaicking method achieves substantial quality and perceptual effect improvement relative to the previous method by Hamilton and Compton and the two state-of-the-art methods, Kwan et al.’s pansharpening-based method, and Kwan and Chou’s deep learning-based method.

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Modified Local and Global Contrast Enhancement Algorithm for Color Satellite Image

EPJ Web of Conferences ◽

10.1051/epjconf/201922404010 ◽

2019 ◽

Vol 224 ◽

pp. 04010

Author(s):

Viacheslav Voronin

Keyword(s):

Image Processing ◽

Image Enhancement ◽

Satellite Images ◽

Color Image ◽

State Of The Art ◽

Satellite Image ◽

Detailed Model ◽

Global Contrast ◽

Enhancement Algorithm

The quality of remotely sensed satellite images depends on the reflected electromagnetic radiation from the earth’s surface features. Lack of consistent and similar amounts of energy reflected by different features from the earth’s surface results in a poor contrast satellite image. Image enhancement is the image processing of improving the quality that the results are more suitable for display or further image analysis. In this paper, we present a detailed model for color image enhancement using the quaternion framework. We introduce a novel quaternionic frequency enhancement algorithm that can combine the color channels and the local and global image processing. The basic idea is to apply the α-rooting image enhancement approach for different image blocks. For this purpose, we split image in moving windows on disjoint blocks. The parameter alfa for every block and the weights for every local and global enhanced image driven through optimization of measure of enhancement (EMEC). Some presented experimental results illustrate the performance of the proposed approach on color satellite images in comparison with the state-of-the-art methods.

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Local Phase Features in Chromatic Domain for Human Detection

International Journal of Monitoring and Surveillance Technologies Research ◽

10.4018/ijmstr.2016070104 ◽

2016 ◽

Vol 4 (3) ◽

pp. 52-72

Author(s):

Hussin K. Ragb ◽

Vijayan K. Asari

Keyword(s):

Color Image ◽

State Of The Art ◽

Color Space ◽

Error Rates ◽

Image Features ◽

Human Detection ◽

Phase Congruency ◽

Illumination Changes ◽

Gradient Based

In this paper, a new descriptor based on phase congruency concept and LUV color space features is presented. Since the phase of the signal conveys more information regarding signal structure than the magnitude and the indispensable quality of the color in describing the world around us, the proposed descriptor can precisely identify and localize image features over the gradient based techniques, especially in the regions affected by illumination changes. The proposed features can be formed by extracting the phase congruency information for each pixel in the three-color image channels. The maximum phase congruency values are selected from the corresponding color channels. Histograms of the phase congruency values of the local regions in the image are computed with respect to its orientation. These histograms are concatenated to construct the proposed descriptor. Results of the experiments performed on the proposed descriptor show that it has better detection performance and lower error rates than a set of the state of the art feature extraction methodologies.

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Analysis and modification of graphic data compression algorithms

Artificial Intelligence ◽

10.15407/jai2020.04.032 ◽

2020 ◽

Vol 25 (4) ◽

pp. 32-40

Author(s):

Bouza M.K. ◽

Keyword(s):

Color Image ◽

Jpeg 2000 ◽

Black And White ◽

Advantages And Disadvantages ◽

Graphic Data ◽

Full Color ◽

Wide Range ◽

Site Design ◽

Lzw Algorithm

The article examines the algorithms for JPEG and JPEG-2000 compression of various graphic images. The main steps of the operation of both algorithms are given, their advantages and disadvantages are noted. The main differences between JPEG and JPEG-2000 are analyzed. It is noted that the JPEG-2000 algorithm allows re-moving visually unpleasant effects. This makes it possible to highlight important areas of the image and improve the quality of their compression. The features of each step of the algorithms are considered and the difficulties of their implementation are compared. The effectiveness of each algorithm is demonstrated by the example of a full-color image of the BSU emblem. The obtained compression ratios were obtained and shown in the corresponding tables using both algorithms. Compression ratios are obtained for a wide range of quality values from 1 to ten. We studied various types of images: black and white, business graphics, indexed and full color. A modified LZW-Lempel-Ziv-Welch algorithm is presented, which is applicable to compress a variety of information from text to images. The modification is based on limiting the graphic file to 256 colors. This made it possible to index the color with one byte instead of three. The efficiency of this modification grows with increasing image sizes. The modified LZW-algorithm can be adapted to any image from single-color to full-color. The prepared tests were indexed to the required number of colors in the images using the FastStone Image Viewer program. For each image, seven copies were obtained, containing 4, 8, 16, 32, 64, 128 and 256 colors, respectively. Testing results showed that the modified version of the LZW algorithm allows for an average of twice the compression ratio. However, in a class of full-color images, both algorithms showed the same results. The developed modification of the LZW algorithm can be successfully applied in the field of site design, especially in the case of so-called flat design. The comparative characteristics of the basic and modified methods are presented.

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Low-Light Image Enhancement Based on Multi-Path Interaction

Sensors ◽

10.3390/s21154986 ◽

2021 ◽

Vol 21 (15) ◽

pp. 4986

Author(s):

Bai Zhao ◽

Xiaolin Gong ◽

Jian Wang ◽

Lingchao Zhao

Keyword(s):

Color Image ◽

State Of The Art ◽

Interaction Network ◽

Feature Representation ◽

Uniform Illumination ◽

Feature Maps ◽

Low Light ◽

Low Contrast ◽

Better Than

Due to the non-uniform illumination conditions, images captured by sensors often suffer from uneven brightness, low contrast and noise. In order to improve the quality of the image, in this paper, a multi-path interaction network is proposed to enhance the R, G, B channels, and then the three channels are combined into the color image and further adjusted in detail. In the multi-path interaction network, the feature maps in several encoding–decoding subnetworks are used to exchange information across paths, while a high-resolution path is retained to enrich the feature representation. Meanwhile, in order to avoid the possible unnatural results caused by the separation of the R, G, B channels, the output of the multi-path interaction network is corrected in detail to obtain the final enhancement results. Experimental results show that the proposed method can effectively improve the visual quality of low-light images, and the performance is better than the state-of-the-art methods.

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