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The problem of image enhancement for low-contrast images is considered. The histogram-based method of automatic contrast enhancement on the basis of the analyzing of contrast distribution at the boundaries of low-contrast image elements (objects and background) using the various definitions of contrast kernels is proposed. The research of the effectiveness of the proposed and the well-known histogram-based...
Histogram equalization is the simplest method of image enhancement. Mean brightness and contrast are important parameters of an image. Artifacts are generated if the original mean brightness of an image is not preserved. A high contrast provides good visual quality. Contrast can be increased by increasing entropy of the image. Entropy can be maximized by making the image histogram as flat as possible...
In this paper, a highly adaptive swarm intelligence inspired optimally gamma corrected intensity coverage maximization approach has been proposed for quality enhancement of dark and low contrast remotely sensed images. Various image enhancement techniques have been proposed till date, but in case of dark images, most of them are suffering from saturation effects in higher intensity regions along with...
Histogram-based image enhancement methods are widely used in image pre-processing, which are vital for the consequential image analysis, feature extraction and object recognition. This paper studies six adaptive methods which modify the conventional histogram equalization (HE) and further concern the local quality of the normalized images. The parameters for controlling the normalization effects are...
The problem of image enhancement for low-contrast images with the small-size objects is considered. The histogram-based method for contrast enhancement of low-contrast images with the small-size objects on the basis of the estimation of parameters of contrast distribution at boundaries of image elements for the various definitions of contrast kernels is proposed. The proposed method is intended for...
Wireless Capsule Endoscopy (WCE) is a latest technology that invents in field of medical which is very useful for diagnosis the disease in a human body. An efficient image enhancement technique for the Capsule Endoscopy is used in this paper. This technique is developed considering the disadvantage of Capsule Endoscopy where as WCE images are dark, low contrast brightness and visibility in natural...
In this paper, a new automatic histogram equalization algorithm which is based on Bi-Histogram Equalization (BHE) is proposed. The proposed method preserves the brightness and also improves the contrast. Mean value of the intensity is used for selecting the thresholds to avoid over enhancement also improving contrast of the image. The calculated mean limits the valley points to divide the histogram...
Research on automated image enhancement has gained momentum in recent years, partially due to the need for easy-to-use tools for enhancing pictures captured by ubiquitous cameras on mobile devices. Many of the existing leading methods employ machine-learning-based techniques, by which some enhancement parameters for a given image are found by relating the image to the training images with known enhancement...
In this paper, an efficient statistical approach, employing a highly adaptive gamma correction based on regionally distributed and independently equalized histograms for all regions followed by contextual clipping, is presented for overall enhancement of low contrast dark images keeping their intrinsic features preserved. For this purpose, input image is uniformly subdivided into several non-overlapping...
Clouds inhibit the features of images such as color and brightness in the image regions. The light diffusion, scattering and attenuation of clouds create blur effect or affect the contrast of the images. The interference of cloud over images degrades the quality of satellite images and tends to suppress the essential information in those images. Hence, the removal of clouds greatly help in the efficient...
Pyramids being an emerging technology in the field of image processing, this paper uses the same for enhancing images using histogram matching. It gives a detailed analysis of enhancing the images by improving their contrasts using histogram matching in the pyramid layers thus extracting the information from the images to the maximum possible. It also shows the variation in the contrast of the images...
This paper presents a new contrast enhancement method using Histogram Equalization named Dualistc Sub-Image and Non-parametric Modified Histogram Equalization (DSINMHE). Our proposed method consists of three steps: (i) The original image is segmented into two sub-images by the median value of the image. (ii) Then we use the histogram modification technique to maximize entropy and control over enhancement...
In view of the low illumination color images, image enhancement technology is commonly used in image processing. In this study, we propose a brightness enhancement algorithm based on the bright channel prior, which focuses on the gray removal. The local patches in sufficient illumination images contain some pixels that have very high intensities in at least one color channel. Using this prior with...
Histogram-Based image enhancement techniques attempts to divide the histogram vertically and horizontally to overcome the saturation effect of intensities and over-enhancement. The proposed cloud-based method makes an effort to modify a classic histogram-based image enhancement by concept of cascade control. Two control loops check the quality of the output image by an inner and outer feedback signals...
In this paper, we present a comprehensive analysis and comparison of state-of-the-art Contrast Enhancement (CE) evaluation metrics. In this work, we developed a new database consisting of 182 images. The subjective experiments were performed to obtain a preference rating from different observers for the enhanced images using six CE methods selected from different representative categories. The quality...
The paper proposes a novel image enhancement method based on histogram equalization called Quadrants Histogram Equalization with a Clipping Limit (QHECL). The proposed method consists of four steps: (i) The first step is to compute the median value of the input image, which is used to divide the input histogram into two sub histograms. (ii) We calculate the average brightness value of each sub histogram...
In low luminance images (night scene), it suffers from various problems, e.g., low overall brightness, poor contrast and serious lack of information. However, in some scenario, strong light also appears in these images. In this case, the regions of high and low luminance both exist, which introduces a more complicated situation for image enhancement. In this paper, we present an enhancement method...
When applying a filter to an image, it often makes practical sense to maintain the local brightness level from input to output image. This is achieved by normalizing the filter coefficients so that they sum to one. This concept is generally taken for granted, but is particularly important where nonlinear filters such as the bilateral or and non-local means are concerned, where the effect on local...
Hazy images hinder image understanding in many applications such as autonomous vehicle. In this paper, we propose an efficient method to improve image quality of hazy images. Our method estimates the transmission function based on a linear model that allows efficient computation and employs quadtree to search for a region that best represents the scatter of airlight. Experiments were conducted using...
Tone mapping is the process of compressing high dynamic range (HDR) images to obtain low dynamic range (LDR) images in order to display them on standard display devices. The methods that perform tone mapping also known as tone mapping operators (TMOs) can be global and process all luminances in the same way, or they can be local and process the luminances with respect to their closer neighborhood...
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