Digital Image Enhancement Research Articles

Digital image enhancement with DStretch®: Is complexity always necessary for efficiency?

DStretch®, plug-in for ImageJ© is designed specifically for the enhancement of digital images of pictographs. It is now widely used in the world since a decade but have thus far rarely been used in French and African rock art studies. Among all the software tools currently available to rock art specialists, it is one of the most efficient to decipher faint paintings and sometimes engravings, while being cheap, fast and easy to use, particularly in harsh or remote environments. Moreover, the enhancement of digital images with DStretch® is almost operator-independent and reproducible thanks to pre-recorded settings, thus improving objectivity. We provide several examples of the benefit of using this tool on various sites, from African prehistoric pictographs to Alpine paintings and petroglyphs, and propose a method for recording rock art panels with DStretch®. But, in spite of these advantages, we have to keep in mind that the final tracings are always subjective and biased by personal perceptions, as demonstrated here by a simple but significant experience.

Evaluating conventional and advanced visible image enhancement solutions to produce digital tracings at el Carche rock art shelter

Advances in rock art recording techniques through non-destructive methods are a priority in rock art research. Developments on computer science, digital photography and more specifically on digital image enhancement have revolutionized the way rock art motifs are recorded and documented today. Conventional software for digital image processing is widely used to produce digital tracings, with reasonable results so far. But this manual process is still time consuming, especially when motifs are either faded, deteriorated or part of complex superimpositions. This paper explores the potential of two advanced digital image enhancement decorrelation techniques, principal components analysis (PCA) and decorrelation stretch (DS) to facilitate and accelerate motif recognition on visible digital images, as a first step in the rock art recording process. Statistical analysis revealed that the performance of PCA is slightly better (5%) than DS, when compared to the results of conventional image enhancement solutions.

Recent advancements in dental digital radiography

For more than a century, now radiographs have been taken using radiographic film. Digital imaging has been replacing traditional films in private practice, academic institutions in the last two decades. As use of digital radiography has become more common in the last decade with rapidly evolving changes in the way healthcare is administered, coupled with the amazing recent advances in imaging, many dental professionals are thinking of using digital system as a substitute to conventional film system. This has necessitated a review of the different technologies used for digital imaging in dentistry with broad overview of the principles in digital system, equipment, digital imaging receptors, procurement, enhancement process, transfer, and storage developments along with comparisons of film-based imaging, processing and image analysis.

High Speed Digital Imaging for Flame Studies: Potentials and Limitations

Abstract Experience has shown that higher shutter speed or framing rate may cause signal drop out and the loss of the weak flame emission. On the other hand, slow shutter speed or frame rate will not be able to resolve the higher flame oscillation frequency. In this study, two synchronised high speed cameras are used to investigate the effect of camera shutter speed and frame rates on the colour imaging quality and oscillation frequency of a premixed methane flame. Through an innovative digital imaging enhancement technique, the weak blue flame colour pixels can be selectively enhanced for better visualisation and analysis. As a result, the same flame imaged at different shutter speed can be compared and contrasted with good accuracy. Test cases are carried out to provide better understanding of flame structure and dynamics.

Simultaneous High Speed Schlieren and Direct Imaging of Ignition Process with Digitally Enhanced Visualisation

Abstract In this paper, a combined method of schlieren and digital colour image processing is developed to study the effect of ignition location on the propagation of propane diffusion flames. The early weak blue flame is visualised through selective digital imaging enhancement techniques, which have revealed that a typical orange diffusion flame is often formed inside a blue flame pocket at the beginning of the ignition when ignited at the centreline of the fuel jet. When the ignition location towards the out edge of the fuel/air mixing boundary, the orange flame shifted and gradually broke the blue flame pocket. In the meantime, the flame was observed to propagate faster. The ratio of orange flame areas rose and the blue flame area fell accordingly.

Image Enhancement using Hardware co-simulation for Biomedical Applications

Digital image enhancement techniques are to improving the visual quality of images. Main objective of image enhancement is to process an image so that result is more suitable than original image for specific application. Image is one of the most fundamental and significant features. The correctness and reliability of its results affect directly the comprehension machine system made for objective world. The implementation of image enhancement algorithms on a field programmable gate array (FPGA) is having advantage of using large memory and embedded multipliers. FPGAs are providing a platform for processing real time algorithms on application-specific hardware with substantially higher performance than programmable digital signal processors (DSPs). This project focus on implementation issues of image enhancement algorithms like brightness control, contrast stretching, negative transformation, thresholding, filtering techniques on FPGA that have become a competitive alternative for high performance digital signal processing applications. This project will use System Generator tool and modular construction methods to build a image algorithm platform in MATLAB. By a brief analysis about display image and resource cons umption after achieving on Spartan-3E development board, we can see the image using System Generator for FPGA algorithm design superiority, have the vast application prospects

Lineament Extraction from SPOT 5 and NigeriaSat-X Imagery of the Upper Benue Trough, Nigeria

Abstract. The Upper Benue Trough is part of the Benue Trough of Nigeria and is comprised of three basins: the east–west trending Yola Basin (Yola Arm), the north–south trending Gongola Basin (Gongola Arm) and the northeast–southwest trending Lau Basin (Main Arm). This research is an ongoing research at understanding the structural framework of the Upper Benue Trough using several techniques including the use of Remote Sensing and GIS. Several digital image enhancement techniques such as general contrast stretching and edge enhancement were applied to the NigeriaSat-X and SPOT 5 image in ERDAS IMAGINE 9.2 after which structures were mapped out on-screen using ArcMap 10. The Digital Elevation Model (DEM) of the Trough was also used to enhance geomorphic features. The analysis carried out on the images revealed that lineaments are abundant in the Upper Benue Trough and they can be subdivided into four major trends, NE–SW, NW–SE, W–E and N–S in order of abundance and range in length from about 300 m to 26 km. Several faults were also mapped out within the Basin such as a sinistral fault around Bakoreji village in Bauchi, a dextral fault close to Kalmai town in Gombe and a dextral fault close to Wong in Taraba. It was discovered that some of the sites where minerals such as lead and zinc ores are being mined occur in the zones of high lineament density. This study shows the capability of the DEM, SPOT 5 and NigeriaSat-X images for lineament/structural interpretations.

Digital image enhancement for recording rupestrian engravings: applications to an alpine rockshelter

Image processing software, such as the DStretch plug-in for ImageJ or Photoshop, are currently used to make faint rupestrian pictographs more legible. During the ongoing study of an Alpine rockshelter, these software proved to be equally useful for the visualization of linear engravings and scratchings. This unexpected function of DStretch, created for the study of rupestrian paintings, made it possible to clarify and correct the previous recordings of an incised Iron Age warrior and to facilitate the digital tracing of a modern maritime scene. Even if such convincing results are determined by particular local geological conditions in this case, this function could facilitate the study of engravings in other contexts where the lithology of smooth rock surfaces produces a sharp contrast with incised images.

EFFICIENT CONTRAST ENHANCEMENT USING GAMMA CORRECTION WITH MULTILEVEL THRESHOLDING AND PROBABILITY BASED ENTROPY

In digital image enhancement, contrast enhancement plays an important role. The main objective of contrast enhancement is to correct the local contrast in different area of the image. So that the feature unseen in the dark or bright area is brought out and exposed to the human views. In this paper improve the brightness of the dimmed images and preservation of image feature via multilevel thresholding, gamma correction and probability based entropy. The proposed method preserves the feature of the image and brightness and also improves image quality.

Digital Grey Scale Image Enhancement based on Anisotropic Non-Linear Diffusion Technique

era of image processing has influenced every part of the universe right from medical field to space research. Digital image enhancement is the process to improve quality metrics of a noisy image. In this presented paper based on anisotropic non-linear diffusion technique to enhance the input noisy gray scale images, here mainly focused on speckle noise, which aremainly cause by today's modern image processing sensing devices. The value of quality matrices of an enhanced image are PSNR 10 dB and SNR 11 dB. After comparison the values of image parameters with different technique, the presented work not only attained the better result but also itreduce the complexity of digital circuit as its fall under spatial domain category. Finally the paper concluded that anisotropic non- linear diffusion technique is efficient forgrey scale image enhancement, especially for reduction of speckle noise. KeywordsEnhancement, Anisotropic, Diffusion, PSNR etc.

Image Enhancement Methods: A Review

Image processing is faced with a number of challenges r anging from unequal resolutions, format variations, non uniform illuminations, distortions and nois e. It is also affected by orientation and contrast differences. In view of these ch allenges, most digital image processing applications or devices employ enhancement procedure prior t o the use of the captured image for intended purposes. This paper reports on the review of so me of the existing digital image enhancement methods with emphasis on methodologies, strengths, limitations and application areas. The specific application of some of these meth ods by different authors is also presented.

Comparison and Enhancement of Digital Image by Using Canny Filter and Sobel Filter

In this research paper we have defining two different edge detection methods i.e canny edge detection and Sobel edge detection and we are also discussing some image quality parameters like PSNR, SNR, MSE, RMSE, UQI and MAE. Edge detection is a technique that is used to identifying points in a digital image at which the image brightness changes sharply or, more formally, has discontinuities. The points at which image brightness changes sharply are typically organized into a set of curved line segments termed edges. Results shows that our strategy on the nature of comparison between canny and sobel edge detection methods by using image quality parameters on Medical images [ MRI and CT Scan] and to further finding a better and more accurate edge detection method .The values of these methods are interpreted and illustrated in results section .

Needle Echogenicity in Ultrasound-Guided Lumbar Spine Injections: A Cadaveric Study

Background: Echogenicity of regional anesthesia needles has been tested on different preclinical models; however, previous studies were done in an ideal experimental setting utilizing highfrequency insonation and superficially located targets. Because steep-angle deep injections are typically required for spinal and other chronic pain procedures, and low-frequency transducers are used, further feasibility study is warranted. Objectives: To determine effectiveness of steep-angle deep injections, typically required for spinal and other chronic pain procedures. Study Design: Experimental laboratory study. Setting: Willed Body Program, University of Washington. Methods: In-plane lumbar spine procedures with 50° and 70° angles were performed on a human cadaver. The images and video clips of a non-echogenic (Quincke-type) and echogenic (SonoPlex, StimuQuick, and EchoStim) needle placements were presented to 3 blinded assessors who rated the needle visibility on a 4-point scale. The data was statistically analyzed to determine the differences in visibility between the needles with and without the digital image enhancement, and to compare the video clips to captured images. Results: ANOVA analysis demonstrated that overall SonoPlex was significantly better (P = 0.02) than other needles. SonoPlex maintained its superiority in the subset of facet joint injections (P = 0.02), followed by Quincke-type, then the StimuQuik, and EchoStim needles. In deep procedures, EchoStim was comparable with SonoPlex (P = 0.03), and they both were better than the other 2 needles. The enhanced images received higher rates, with a 0.6 point mean improved rating (P = 0). Limitations: This study is limited by choice of needles, number of experiments performed, and potential postmortem changes of echogenicity. Conclusions: The SonoPlex needle appeared to have better echogenicity in this study. While nonechogenic Quincke-type needle visibility was adequate in superficial placements, it was limited in deep injections. An imaging enhancement is effective in improving needle visibility and should be used whenever possible. Key words: Spinal injections, ultrasound, echogenic needle

Segment dependent dynamic multi-histogram equalization for image contrast enhancement

Histogram equalization (HE) method proved to be a simple and most effective technique for contrast enhancement of digital images. However it does not preserve the brightness and natural appearance of the images, which is a major drawback. To overcome this limitation, several Bi- and Multi-HE methods have been proposed. Although the Bi-HE methods significantly enhance the contrast and may preserve the brightness, the natural appearance of the images is not preserved as these methods suffer with the problem of intensity saturation. While Multi-HE methods are proposed to further maintain the brightness and natural appearance of images, but at the cost of contrast enhancement. In this paper, two novel Multi-HE methods for contrast enhancement of natural images, while preserving the brightness and natural appearance of the images, have been proposed. The technique involves decomposing the histogram of an input image into multiple segments based on mean or median values as thresholds. The narrow range segments are identified and are allocated full dynamic range before applying HE to each segment independently. Finally the combined equalized histogram is normalized to avoid the saturation of intensities and un-even distribution of bins. Simulation results show that, for the variety of test images (120 images) the proposed method enhances contrast while preserving brightness and natural appearance and outperforms contemporary methods both qualitatively and quantitatively. The statistical consistency of results has also been verified through ANOVA statistical tool.

Coal Transport Tape Control System Based on Machine Vision

Coal transport security is one of the important links of mining safety in production chain. Most of Mines use long distance wire rope core belt conveyor transporting coal. By the reason of the load increases, the belt surface scratches and aging etc when the transmission belt in the long run, will cause the wire rope core corrosion, fracture, joint elongation, wire rope core and transmission belt adhesion decreased and finally the joint tensile fault. Once a fault occurs, the transmission security not only endangers mine, even causes the entire production system halted, so the security warning mechanism of coal transport tape proposed must be enforced. Article using machine vision and online transmission detection combined. In the first field observation, using the high accuracy linear array CCD real-time transmission of high-speed operation with the image acquisition and image processing threshold; Though extraction algorithm, simulation experiment and field test; finally comprehensive analysis gives the early warning scheme. The project mainly studies the transmission belt blob spot detection and algorithm with wear, based on digital image, image coding and image enhancement, compared the collected image speckle with set threshold so as to determine which set of real-time image for pre-alarm wear spots, mark the spot coordinates, at the same time to upload data in order to complete the transmission belt warning. The project solves the influence of transmission tape failure of coal production effectively.

Local Statistic Enhancement of Digital Image Based on Genetic Algorithm

Iamge repair using the digital image processing technology has become a new research point in computer application. A novel method of local statistic enhancement based on genetic algorithm is proposed in this paper for the image enhancement. The modified amplified function are used as the jugement criterion, and the optimal paremeters are searched by the genetic algorithm. Experimental results show that the quality of images is improved dramatically by using this method.

Study of Segmentation Threshold Based on Wavelet Transform

Based on the research of the four kinds of algorithms of digital image segmentation, based on edge detection methods, based on region growing method, threshold segmentation method and digital image threshold segmentation method based on wavelet transform, using MATLAB simulation of all digital image enhancement and segmentation process, the obtained results are analyzed, proving the threshold segmentation wavelet transform method has unparalleled advantages in information extraction in medical image. Wavelet transform is a mathematical tool widely used in recent years, compared with the Fu Liye transform, the window of Fu Liye transform, wavelet transform is the local transform of space and frequency, it can be very effective in extracting information from the signal [[1.

Application of image enhancement method for digital images based on Retinex theory

The image enhancement and implementation of the methods for the digital image enhancement were studied. The characteristics of different image enhancement methods, including contrast enhancement, linear transformation, piecewise linear transformation, grayscale slice transformation and Retinex clearing algorithms were analyzed in detail. Retinex enhancement algorithms were studied and the implementation process for the Retinex algorithm is given. Finally, an example of image enhancement using the multi scale Retinex algorithm (MSR) is achieved. It is shown that MSR can realize the image color constancy, local dynamic range compression, color enhancement and the overall dynamic range compression under certain circumstances.

Oversampling advances in millimeter-wave scan imaging using inexpensive neon indicator lamp detectors

In recent years, much effort has been invested to develop room temperature inexpensive, but sensitive, millimeter wave (MMW) and terahertz (THz) detectors that can be used as pixels in focal plane arrays, which is important for real-time imaging. A new 18×2 neon indicator lamp MMW/THz scanner was developed. The components of the camera include horizontally shifted two-column glow discharge detectors in a scanning array. The detectors, costing about 50 cents each, are wired to a preprocessing card, a VLSI board, and a motor for scanner movement. A description of the VLSI Verilog programmable hardware of the new scanner, the physical architecture, the software user interface, and imaging results at 97 GHz are presented. At this stage, the emphasis is focused on the lamp exposure time and spatial resolution when the scanning is performed horizontally. In the future it is planned to expose all pixels simultaneously for real-time imaging. New software capabilities allow the application of digital image enhancement algorithms. Fast scanning permits obtaining images in 1 to 5 s. Oversampling yields a sharper edge response and a higher signal-to-noise ratio.

A new histogram equalization method for digital image enhancement and brightness preservation

This paper proposes a new histogram equalization method for effective and efficient mean brightness preservation and contrast enhancement, which prevents intensity saturation and has the ability to preserve image fine details. Basically, the proposed method first separates the test image histogram into two sub-histograms. Then, the plateau limits are calculated from the respective sub-histograms, and they are used to modify those sub-histograms. Histogram equalization is then separately performed on the two sub-histograms to yield a clean and enhanced image. To demonstrate the feasibility of the proposed method, a total of 190 test images are used in simulation and comparison, in which 72 of them are standard test images, while the remainder are made up of real natural images obtained from personal digital camera. The simulation results show that the proposed method outperforms other state-of-the-art methods, both in terms of visual and runtime comparison. Moreover, the simple implementation and fast runtime further underline the importance of the proposed method in consumer electronic products, such as mobile cell-phone, digital camera, and video.