Showing papers on "Histogram equalization published in 1977"
TL;DR: A memoryless nonlinear, space-invariant transformation of the pixel brightness values is proposed in this paper, which is based upon the histogram of the picture to be processed and the nature of human brightness perception.
161 citations
TL;DR: Histogram peaks can be sharpened using an iterative process in which large bins grow at the expense of nearby smaller bins to facilitate compressing or segmenting it.
Abstract: : Histogram peaks can be sharpened using an iterative process in which large bins grow at the expense of nearby smaller bins. The modified histogram will consist of a few spikes corresponding to the peaks of the original histogram. The image corresponding to the modified histogram is often almost undestinguishable from the original image. The small number of different gray levels in that image can be used to facilitate compressing or segmenting it.
59 citations
01 Jan 1977
TL;DR: In this paper, a gray-level transformation method suitable for interactive image enhancement was presented, where the well-known histogram equalization approach is a special case of this method and a technique for improving the uniformity of a histogram is also developed.
Abstract: A gray-level transformation method suitable for interactive image enhancement was presented. It is shown that the well-known histogram equalization approach is a special case of this method. A technique for improving the uniformity of a histogram is also developed. Experimental results which illustrate the capabilities of both algorithms are described. Two proposals for implementing gray-level transformations in a real-time interactive image enhancement system are also presented.
58 citations
TL;DR: In this paper, a gray-level transformation method suitable for interactive image enhancement is presented, and the well-known histogram equalization technique is a special case of this method.
52 citations
01 Jul 1977
TL;DR: The development of a real-time TV compatible contrast enhancement unit was conducted as the result of a three phase study program to evolve and evaluate, by computer simulation, alternate contrast enhancement techniques.
Abstract: : The development of a real-time TV compatible contrast enhancement unit was conducted. This development was the result of a three phase study program to evolve and evaluate, by computer simulation, alternate contrast enhancement techniques. The three techniques studied were the Local Area Histogram Equalization (LAHE), Local Area Brightness and Gain Control (LABGC), and Haar Transform Filtering (HTF). The three techniques studied were the Local Area Histogram Equalization (LAHE), Local Area Brightness and Gain Control (LABGC), and Haar Transform Filtering (HTF). The LABGC technique was selected for hardware implementation due to its relative simplicity and simulated performance. The LABGC algorithm basically operates on and adjusts the gain and bias of a single pixel element as a function of the statistics of immediate surrounding pixels. If there is a wide variation in the values (high contrast) no gain is applied; conversely, high gain is applied when the immediate area exhibits small variations (low contrast). During the first part of this project, a design study was conducted using the computer simulation model to optimize the mechanization parameters. In particular, the pixel area size of 4 x 4 pixels was selected, the video is digitized to 6 bits and multiple gain transfer functions were selected. An all digital mechanization was selected in order to eliminate analog noise and nonlinearity problems.
1 citations