China
Africa
Explore chapters and articles related to this topic
Image Enhancement in Spatial Domain
Published in Vipin Tyagi, Understanding Digital Image Processing, 2018
Many devices, e.g., a monitor used for input and output, respond according to a power-law. The process used in order to reduce the effect of power-law response phenomena is called gamma correction. For example, on some monitors, the image displayed is darker than the actual input image. In such cases, there is a need to correct this effect before displaying the image. Gamma correction changes the intensity of the displayed image as well as the ratios of red to green to blue in a color image. Gamma correction is very important in the case of the images used on websites, as the image has to be displayed on various monitors having different values of gamma.
G
Published in Phillip A. Laplante, Dictionary of Computer Science, Engineering, and Technology, 2017
Inside a CRT, the luminance of a pixel is represented by a voltage V; however, the luminance of the ray produced by that voltage is not proportional to V, but rather to V, where γ is a device-dependent constant between 2 and 2.5. It is thus necessary to compensate for this effect by transforming the luminance L into L1/γ; this is called gamma correction. Some CCD cameras implement gamma correction directly on the signal that they generate. Some computer monitors allow modification of the factor γ or gamma correction through software.
Technology Beyond the Standard
Published in Klaus Diepold, Sebastian Moeritz, Understanding MPEG-4, 2012
Klaus Diepold, Sebastian Moeritz
Gamma correction (non-linear relationship between signal voltage and image brightness) is yet another analog technique to adjust the video signal and the physical characteristics of CRT screens and computer monitors—to better match the characteristics of the human visual perception.
Image Enhancement and Implementation of CLAHE Algorithm and Bilinear Interpolation
Published in Cybernetics and Systems, 2022
Venkatesh S., John De Britto C., Subhashini P., Somasundaram K.
Different approaches for low illumination enhancement include methods based on histogram equalization, (Ferguson et al. 2008), noise removal using wiener filter, linear contrast adjustment, CLAHE method and other existing methods. The proposed work is based on image contrast, color enhancement using adaptive gamma correction and histogram equalization. Histogram equalization is used to enhance the digital images, but in most cases it results in over illumination and intensity saturation. The work is based on performing gamma correction adaptively and histogram distribution method for contrast improvement. The gamma correction can be performed adaptively to adjust and enhance the contrast. The weighted histogram distribution presented in the work preserves the color and provides the fine details.
Analysis of the influence of pre-processing techniques with convolutional neural networks for automatic detection of cysts in wisdom teeth
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Danilo Oliveira, J. B. Barreto, I. M. Mesquita, I. C. Paula Jr, F. N. Chaves, M. B. S. Sampieri, J. P. Madeiro
Gamma correction consists of applying a power function to the image for contrast manipulation. Varying the gamma value can generate a family of diverse transformations that enhance high or low intensities (Gonzales and Woods 2008). The gamma function used in this work is defined by:
Driver Fatigue Detection Using Viola Jones and Principal Component Analysis
Published in Applied Artificial Intelligence, 2020
Bahjat Fatima, Ahmad R. Shahid, Sheikh Ziauddin, Asad Ali Safi, Huma Ramzan
In this step, we extracted frames from the video and every 10th frame is taken as input. Input frame is preprocessed by converting to grayscale followed by the gamma correction. Gamma correction controls the overall lightness or darkness of the image and is used to improve the image quality (Figure 6).