Red Green Blue Values Research Articles

FPGA Open Architecture Design for a VGA Driver

This work presents an open architecture proposal for a VGA (Video Generic Array) controller to be used into embedded systems based in FPGA. Several developers of hardware design, which use some hardware description language, have a video library to be used with VHDL or Verilog language, but in most of cases, we need to buy an expensive annual license, and can be used only for the manufacturer hardware. This controller is developed using only VHDL based in the IEEE standards, to ensure the portability with any manufacturer, and this is part of the contribution of this work. The controller designed is generic, due that it can be used for any resolution used by a commercial monitor, including the widescreen monitor. The generic controller will be used for image processing research. The work presents two kinds of test: first, we display the eight basics color generated with the RGB (Red, Green, Blue) values; second, an image is stored into an external memory RAM (Random Access Memory), and the FPGA reads and display the image into a CRT (Cathode Ray Tube) and LCD (Liquid Crystal Display) monitor.

Indirect determination of sodium diclofenac, sodium dipyrone and calcium gluconate in injection drugs using digital image-based (webcam) flame emission spectrometric method

This paper proposes a digital image-based flame emission spectrometric (DIB-FES) method for indirect determination of sodium diclofenac, sodium dipyrone and calcium gluconate in injectable forms. The proposed DIB-FES method uses digital images obtained from a webcam, based on the RGB (Red-Green-Blue) system. It offers a simple and inexpensive way to quantify these organic substances using the radiation emitted by the alkaline and earth-alkaline metals present in their formulae. Analytical curves were constructed on the basis of the relationship between RGB values and calibration solution concentrations. The results showed no statistical difference between the proposed and reference methods when applying the paired t-test at a 95% confidence level. The proposed DIB-FES method also performed well in terms of the figures of merit LOD, LOQ, linear range, precision, and the accuracy as revealed by recovery tests.

Hue-Shift Modeling and Correction Method for High Luminance Display

The human eye usually experiences a loss of color sensitivity when it is subjected to high levels of luminance, and perceives a discrepancy in color between high and normal-luminance displays, generally known as a hue shift. Accordingly, this paper models the hue-shift phenomenon and proposes a hue correction method to provide perceptual matching between high and normal-luminance displays. The modeling of the hue-shift phenomenon is determined by perceived hue matching experiments. To quantify the hue-shift phenomenon for the whole hue angle, 24 color patches with the same lightness are first created and equally spaced inside the hue angle for three lightness levels. These patches are then displayed one-by-one on both displays with the ratio of luminance between the two displays. Next, the hue value for each patch appearing on the high luminance display is adjusted by observers until the perceived hue for the patches on both displays appears the same visually. After obtaining the hue-shift values from the perceived hue matching experiment, these values are fit piecewise into seven sinusoidal functions to allow the shifted-hue amounts to be approximately determined for arbitrary hue values of pixels in a high luminance display and then used for correction. Essentially, the input red green blue (RGB) values of an image are converted to CIELAB values by a forward characterization model, and then, LCh (lightness, chroma, and hue) values are calculated to obtain the hue values for all the pixels. These hue values are shifted according to the amount calculated by the functions of the hue-shift model. Finally, the corrected CIELAB values are calculated from lightness, chroma, and corrected hue values, and after that, the output RGB values for all pixels are estimated by an inverse characterization model. For evaluation, an observer's preference test was performed using several test images with other hue shift results and the comparison results are shown with a z score.

Metamer sets without spectral calibration

The set of metamers for a given device response can be calculated given the device's spectral sensitivities. Knowledge of the metamer set has been useful in practical applications such as color correction and reflectance recovery. Unfortunately, the device sensitivities of a camera or scanner are not known, and they are difficult to estimate reliably outside the laboratory. We show how metamer sets can be calculated when a device's spectral sensitivities are not known. The result is built on two observations: first, the set of all reflectance spectra consists of convex combinations of certain basic colors that tend to be very bright (or dark) and have high chroma; second, the convex combinations that describe reflectance spectra result in convex combinations of red-green-blue (RGB) values. Thus, given an RGB value, it is possible to find the set of convex combinations of the RGB values of the basic colors that generate the same RGB value. The corresponding set of convex combinations of the basic spectra is the metamer set.

Color matching that improves image quality on mobile phone displays

With digital convergence, color reproduction technology for mobile phones continues to improve. Camera technology now enables users to take both still and moving pictures, store them as digital files, and then display or project them anywhere. Color fidelity remains a challenge, however, and LCDs on mobile phones require real-time color matching between camera and cellular screen to ensure image quality. Our proposed color-matching system, shown schematically in Figure 1, comprises three steps: characterization of LCD and camera, gamut mapping, and application of a 16bit-based lookup table (LUT) design.? Device characterization defines the relationship between the tristimulus values (color spaces CIEXYZ or CIELAB) and RGB (red, green, blue) digital values. In general, characterization is modeled by polynomial regression, and as the polynomial order increases, performance improves.? However, for higher-order polynomials, most estimated tristimulus values exceed the boundary of maximum lightness and chroma. This makes implementation difficult because the relationship between tristimulus and digital RGB values has not been analyzed. We suggest a polynomial order based on investigating the relation between RGB digital values, then transformed using opponent color theory and CIELAB values. Meanwhile, for the mobile LCD characterization, we use a sigmoid function instead of a conventional method such as the GOG or S-curved model, to estimate the luminance curve made by the system designer.? This aims at better color reproduction and improved contrast. Additionally, characterization is based on the 16bit processing that controls the mobile LCD, in contrast to digital TVs or monitors, with 24bit data. Figure 1. Block-diagram of the proposed color-matching system.

Viability and acrosome staining of stallion spermatozoa by Chicago sky blue and Giemsa

A simple trypan blue-neutral red-Giemsa staining procedure for simultaneous evaluation of acrosome, sperm head, and tail membrane integrity and morphology has been used to evaluate equine spermatozoa. Some special characteristics and problems have arisen in evaluating stallion semen. One problem was the differentiation of intact vs. damaged sperm tails primarily in frozen and thawed samples. After freezing and thawing, a high percentage of spermatozoa with an unstained head and stained tail were observed. These cells are considered immotile. Therefore, unambiguous differentiation of intact vs. damaged sperm tail membrane is very important for evaluating semen quality. The aim of our study was to develop a method especially for stallion sperm to distinguish more accurately the different cell types. We compared Chicago sky blue 6B (CSB) to trypan blue (TB) for viability staining. CSB/Giemsa staining showed good repeatability and agreement with TB/Giemsa measurements. For densitometry analysis, individual digital images were taken from smears stained by CSB/Giemsa and by TB/Giemsa. A red-green-blue (RGB) histogram for each area of spermatozoa was drawn. Differences of means of RGB values of live vs. dead tails and separate live vs. dead heads from each photo were used to compare the two staining procedures. CSB produced similar live/dead sperm head differentiation and better tail differentiation. TB can be replaced by CSB and this results in more reliable evaluation. After staining with 0.16% CSB and 4 min fixation, 2–4 h Giemsa staining at 25–40° C is recommended for stallion semen.

Using a digital camera for water quality measurements in Galway Bay

A method for using the red–green–blue ( RGB) digital output from a digital camera, a Nikon Coolpix 885, to estimate water quality parameters is described. To eliminate reflection from the water surface, a tube is fitted around the camera lens which breaks the surface such that only the upwelling light from below is measured. To obtain consistency between stations, RGB values used for analysis are taken where the total cameras response ( R + G + B) is a constant value, derived from pictures taken at a range of exposures. The method has been successfully used in Galway Bay, where the optical characteristics of the coastal water are dominated by yellow substance (or coloured dissolved organic material – CDOM) and chlorophyll. A strong linear relationship was found between CDOM and the Red/Blue camera output. The form of the relationship was consistent with previous measurements using more conventional narrow band irradiance sensors. In addition, a log–log relationship between chlorophyll and the Green/Blue camera output was also found. Some problems exist with the use of the camera, particularly with the cameras automatic functions such as ‘white balance’ which may artificially change the RGB output. Nevertheless, the use of a camera for simple water quality measurements has been demonstrated.

Set theoretic estimation in color scanner characterization

A set theoretic approach for the spectral characterization of a color scanner is described. These devices usually employ three channels to obtain a device dependent RGB (red, green, blue) image. To display/print an image, the device dependent RGB values must be correctly transformed to the color space of the target device. To determine accurate and efficient transformations for a number of devices, knowledge of the spectral sensitivity of the scanner is essential. Direct measurement of the sensitivity requires a set of expensive narrow band reflectances and is often infeasible. Methods that estimate the spectral sensitivity based on measurements with typical reflectance samples are therefore of interest. Due to the low dimensionality of the space of object reflectance spectra, this is a highly ill-conditioned problem. As a result, conventional estimation techniques that fail to take a priori knowledge into account perform rather poorly on this problem. A set theoretic approach that incorporates available a priori knowledge into the estimation framework yields better results. Results are presented for a simulated scanner characterization problem and for an actual characterization to demonstrate the increased accuracy compared with conventional methods.

Three fringe photoelasticity ‐ use of colour image processing hardware to automate ordering of isochromatics

AbstractThe early application of digital image processing (DIP) technique to automate photoelastic analysis is based on black and white (B & W) image processing systems. The various methodologies reported can be traced to rely upon one or several features of a B &W DIP system. With the advancements in computer technology, nowadays colour image processing systems are available at affordable prices. A systematic study has been carried out on how to use the red green blue (RGB) value recorded using a colour image processing system for determining fringe orders up to 3 in a fringe field. The study has revealed that instead of directly using RGB values corresponding to a dark field image, if the difference of RGB values between bright anddarkfield images is used, the number of noise points is less. Experiments have been carried out for several arbitrary lines in a circular disk under diametral compression and the results are found to be good.

Munsell soil color and soil reflectance in the visible spectral bands of landsat MSS and TM data

Color is widely used for soil characterization in the field and for soil classification. Standardized soil color notation is usually achieved by comparison with Munsell color charts. These raw color data are generally not easily related to soil spectral properties. The spectral reflectance curves of 84 soil samples were measured with a spectrophotometer in the laboratory. For each sample, chromaticity coordinates were computed according to CIE standard methods and expressed in RGB (Red, Green, Blue) notation using colorimetric equations. RGB values appear to be strongly correlated with the soil reflectance measured in the corresponding spectral bands of Landsat sensors. RGB coordinates were also estimated from Munsell data using convertion tables. Despite their low precision, the estimated color coordinates are significantly correlated with the reflectance values in the Thematic Mapper visible bands. These results allow the interpretation of published data and further development of soil color remote sensing.