Low-contrast enhancement for electro-optic data

1997 ◽  
Author(s):  
Andrew J. Nevis
Keyword(s):  
Contrast Enhancement ◽  
Low Contrast ◽  
Electro Optic

scholarly journals DETECTABILITY OF SIMULATED LOW-CONTRAST OBJECT USING COMPUTED RADIOGRAPHY : DIFFERENCES FOR INCIDENT DOSE, PRIMARY FRACTION AND CONTRAST ENHANCEMENT

1993 ◽  
Vol 49 (4) ◽  
pp. 570-575 ◽  
Author(s):  
KAZUMI KANAI ◽  
AKIYOSHI OHTSUKA ◽  
MASAHIRO HASHIDA ◽  
SHUICHI YAMAUCHI ◽  
KATSUHIKO UEDA ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Computed Radiography ◽  
Low Contrast ◽  
Primary Fraction

Contrast Enhancement Using Optimum Threshold Selection

2020 ◽  
Vol 8 (3) ◽  
pp. 96-118
Author(s):  
Geeta Rani ◽  
Monika Agarwal
Keyword(s):  
Contrast Enhancement ◽  
Maximum Entropy ◽  
Dynamic Range ◽  
Threshold Value ◽  
Histogram Equalization ◽  
Threshold Method ◽  
Essential Information ◽  
Low Contrast ◽  
Brightness Preservation ◽  
Double Threshold

In the recent era, a boom was observed in the field of information retrieval from images. Digital images with high contrast are sources of abundant information. The gathered information is useful in the precise detection of an object, event, or anomaly captured in an image scene. Existing systems do uniform distribution of intensities and apply intensity histogram equalization. These improve the characteristics of an image in terms of visual appearance. The problem of over enhancement and the increase in noise level produces undesirable visual artefacts. The use of Otsu's single threshold method in existing systems is inefficient for segmenting an image with multiple objects and complex background. Additionally, these are incapable to improve the yield of the maximum entropy and brightness preservation. The aforementioned limitations motivate us to propose an efficient statistical pipelined approach, the Range Limited Double Threshold Weighted Histogram Equalization (RLDTWHE). This approach is an integration of Otsu's double threshold, dynamic range stretching, weighted distribution, adaptive gamma correction, and homomorphic filtering. It provides optimum contrast enhancement by selecting the best appropriate threshold value for image segmentation. The proposed approach is efficient in the enhancement of low contrast medical MRI images and digital natural scene images. It effectively preserves all essential information recorded in an image. Experimental results prove its efficacy in terms of maximum entropy preservation, brightness preservation, contrast enhancement, and retaining the natural appearance of an image.

scholarly journals Contrast Enhancement for Topographic Imaging in Confocal Laser Scanning Microscopy

2019 ◽  
Vol 9 (15) ◽  
pp. 3086
Author(s):  
Lena Schnitzler ◽  
Markus Finkeldey ◽  
Martin R. Hofmann ◽  
Nils C. Gerhardt
Keyword(s):  
Integrated Circuits ◽  
Contrast Enhancement ◽  
Laser Scanning ◽  
Simulated Data ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Low Contrast ◽  
Semiconductor Test ◽  
Contrast Structures ◽  
Topographic Imaging

The influence of the axial pinhole position in a confocal microscope in terms of the contrast of the image is analyzed. The pinhole displacement method is introduced which allows to increase the contrast for topographic imaging. To demonstrate this approach, the simulated data of a confocal setup as well as experimental data is shown. The simulated data is verified experimentally by a custom stage scanning reflective microscopy setup using a semiconductor test target with low contrast structures of sizes between 200 nm and 500 nm. With the introduced technique, we are able to achieve a contrast enhancement of up to 80% without loosing diffraction limited resolution. We do not add additional components to the setup, thus our concept is applicable for all types of confocal microscopes. Furthermore, we show the application of the contrast enhancement in imaging integrated circuits.

Evaluation of analog contrast enhancement and digital unsharp masking in low contrast portal images

1989 ◽  
Vol 17 ◽  
pp. 159-160
Author(s):  
J. Weiser ◽  
D. Gur ◽  
M. Deutsch ◽  
R. Gennari ◽  
W. Bloomer ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Low Contrast ◽  
Unsharp Masking ◽  
Portal Images

scholarly journals A High-Performance Infrared Imaging System with Adaptive Contrast Enhancement

2021 ◽  
Author(s):  
Feng Deng ◽  
Zhong Su ◽  
Rui Wang ◽  
Jun Liu ◽  
Yanzhi Wang
Keyword(s):  
Contrast Enhancement ◽  
Real Time ◽  
Infrared Imaging ◽  
Imaging System ◽  
Bilateral Filter ◽  
Base Layer ◽  
Low Contrast ◽  
Infrared Imaging System ◽  
Computing Performance ◽  
Image Details

Most of the existing infrared imaging systems employ the scheme of FPGA/FPGA+DSP with numerous peripheral circuits, which leads to complex hardware architecture, limited system versatility, and low computing performance. It has become an intriguing technical problem worldwide to simplify the system structure while improving the imaging performance. In this paper, we present a novel real-time infrared imaging system based on the Rockchip’s RV1108 visual processing SoC (system on chip). Moreover, to address the problem of low contrast and dim details in infrared images with a high dynamic range, an adaptive contrast enhancement method based on bilateral filter is proposed and implemented on the system. First, the infrared image is divided into a base layer and a detail layer through bilateral filter, then the base layer is compressed by an adaptive bi-plateau histogram equalization algorithm, and finally a linear-weighted method is used to integrate the detail layer to obtain the image with enhanced details. The experimental results indicate that compared with traditional algorithms, our method can effectively improve the overall contrast of the image, while effectively retaining the image details without noise magnification. For an image of 320*240 pixels, the real-time processing rate of the system is 68 frames/s. The system has the characteristics of simplified structure, perceptive image details, and high computing performance.

scholarly journals Optimal CT Contrast Enhancement Protocol for the Fontan Pathway: An Analysis Based on a 15-year Single-center Experience

2021 ◽  
Author(s):  
Hyun Woo Goo
Keyword(s):  
Standard Deviation ◽  
Contrast Agent ◽  
Contrast Enhancement ◽  
Quantitative Evaluation ◽  
Characteristic Curve ◽  
Low Contrast ◽  
Group 3 ◽  
Heterogeneous Enhancement ◽  
Standard Deviations ◽  
Noise Ratio

Abstract This retrospective study was performed to systemically compare several candidates for optimal contrast enhancement protocols of cardiothoracic CT dedicated for evaluating the Fontan pathway. Of 115 CT examinations from 89 patients, simultaneous injection of contrast agent via the arm and leg veins with 50% diluted contrast agent (group 1, n = 38), 60-second scan delay after leg vein injection (group 2, n = 41) or 3-minute scan delay (group 3, n = 36) was used to obtain optimal contrast enhancement. The degree and heterogeneity of cardiovascular enhancement, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were quantitatively evaluated. Histogram-assisted semi-quantitative evaluation was performed for heterogeneous enhancement, and a cut-off value indicating heterogeneous enhancement was determined by comparing the standard deviations between the cases showing homogeneous and heterogeneous enhancement. Contrast enhancement of the Fontan pathway, the standard deviation measured in the Fontan pathway, SNR, and CNR were more frequently lower in group 3 compared to groups 1 and 2 (p < 0.001). Homogeneous enhancement of the Fontan pathway based on the histogram-assisted semi-quantitative evaluation was more frequently seen in group 3 compared to groups 1 and 2 (p < 0.043‒0.001). Receiver operating characteristic curve analysis demonstrated that the standard deviation was an excellent diagnostic test in determining the homogeneity of contrast enhancement (area under the curve = 0.991; 95% confidence interval, 0.988‒0.994; p < 0.001). Standard deviations > 105.1 HU could be considered to indicate heterogeneous enhancement with 73.2% sensitivity and 100.0% specificity. The protocol using a 3-minute scan delay best achieved homogeneous contrast enhancement in the Fontan pathway on cardiothoracic CT among the tested protocols. However, low contrast enhancement, SNR, and, CNR need to be improved.

scholarly journals A POSHE-Based Optimum Clip-Limit Contrast Enhancement Method for Ultrasonic Logging Images

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3954 ◽  
Author(s):  
Qingqing Fu ◽  
Zhengbing Zhang ◽  
Mehmet Celenk ◽  
Aiping Wu
Keyword(s):  
Contrast Enhancement ◽  
Structural Similarity ◽  
Histogram Equalization ◽  
Input Image ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Low Contrast ◽  
Perceptual Evaluation ◽  
Limit Value ◽  
Enhancement Method

Enabled by piezoceramic transducers, ultrasonic logging images often suffer from low contrast and indistinct local details, which makes it difficult to analyze and interpret geologic features in the images. In this work, we propose a novel partially overlapped sub-block histogram-equalization (POSHE)-based optimum clip-limit contrast enhancement (POSHEOC) method to highlight the local details hidden in ultrasonic well logging images obtained through piezoceramic transducers. The proposed algorithm introduces the idea of contrast-limited enhancement to modify the cumulative distribution functions of the POSHE and build a new quality evaluation index considering the effects of the mean gradient and mean structural similarity. The new index is designed to obtain the optimal clip-limit value for histogram equalization of the sub-block. It makes the choice of the optimal clip-limit automatically according to the input image. Experimental results based on visual perceptual evaluation and quantitative measures demonstrate that the proposed method yields better quality in terms of enhancing the contrast, emphasizing the local details while preserving the brightness and restricting the excessive enhancement compared with the other seven histogram equalization-based techniques from the literature. This study provides a feasible and effective method to enhance ultrasonic logging images obtained through piezoceramic transducers and is significant for the interpretation of actual ultrasonic logging data.

Memetic Algorithm Image Enhancement for Preserving Mean Brightness Without Losing Image Features

2019 ◽  
Vol 19 (04) ◽  
pp. 1950020
Author(s):  
Mitra Montazeri
Keyword(s):  
Contrast Enhancement ◽  
Dynamic Range ◽  
Memetic Algorithm ◽  
Image Features ◽  
Image Contrast ◽  
Consumer Electronics ◽  
Major Step ◽  
Processing Application ◽  
Low Contrast ◽  
Image Contrast Enhancement

In the image processing application, contrast enhancement is a major step. Conventional contrast enhancement methods such as Histogram Equalization (HE) do not have satisfactory results on many different low contrast images and they also cannot automatically handle different images. These problems result in specifying parameters manually to produce high contrast images. In this paper, an automatic image contrast enhancement on Memetic algorithm (MA) is proposed. In this study, simple exploiter is proposed to improve the current image contrast. The proposed method accomplishes multi goals of preserving brightness, retaining the shape features of the original histogram and controlling excessive enhancement rate, suiting for applications of consumer electronics. Simulation results shows that in terms of visual assessment, peak signal-to-noise (PSNR) and Absolute Mean Brightness Error (AMBE) the proposed method is better than the literature methods. It improves natural looking images specifically in images with high dynamic range and the output images were applicable for products of consumer electronic.

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