Color ratios

Figure 2. Effect of time of sampling and cultivar on the a/b color ratios of citrus peel. The a/b ratios are negative for green, approximate zero for yellow, and are positive for orange through red.

Funt and Finlayson (1995) proposed histogramming of color ratios. They suggested computing the ratios between adjacent pixels. Let c = [cr, cg, ct]T and c = [c, c g, c h 1 be two colors that are obtained from two adjacent pixel positions. Assuming that the sensors are narrow band, the intensity measured by the sensor at position (x, y) is given by... 

There are other minor nonequivalencies of ISO test procedures compared to ASTM standards, but for color difference the ISO Test Procedure No. 105 is unique. Those who use Colour Measurement Committee (CMC) procedures—particularly CMC 2 1 Lightness to Color ratio—claim that it facilitates a uniform description for acceptability decisions that is better than any other system in existence. These equations permit the use of a single number tolerance, DEcmc, in a nearly uniform color space. The CMC formula is a modification to the perceptibility CIELAB formula. It is fully described elsewhere in this book, but it deserves some brief notice here because, after all, it is an ISO procedure. The CMC developed the basic British Standard No. 6923, Calculation of Small Color Differences. Soon afterward, in 1989, the American Association of Textile Chemists and Colorists (AATCC) adopted AATCC Test Method 173, CMC Calculation of Small Color Differences for Acceptability. Ford Motor Company indicated a preference for using CMC 2 1 ratio color difference for plastics weathering data for plastics interior trim materials. 

Equation (4-116) shows that the color ratio of the indicator is determined by the ratio of concentrations of salt to base and therefore is independent of dilution at a given point in the titration (neglecting solvolysis). As previously indicated, in Equation... 

The color ratio of the indicator therefore varies with the square root of salt concentration. The hydrogen ion concentration at the equivalence point has been shown in (4-56) to be independent of salt concentration. 

Beyond the equivalence point the ratio of acid to alkaline forms of the indicator is proportional to the concentration of excess perchloric add. Thus, upon 10-fold dilution the color ratio decreases 10-fold, while the hydrogen ion concentration decreases by a factor of -s/lO. Again, the indicator color is not a straightforward index of acidity. 

Hapke B., Christman C., Rava B. B., and Mosher J. (1980) A color-ratio map of Mercury. Proc. 11th Lunar Planet. Sci. Conf. 1, 817-821. 

Rava B. and Hapke B. (1987) Analysis of the Mariner 10 color ratio map of Mercury. Icarus 71, 397—429. 

Fig. 2 Overview of the software parameters used by the computer to discriminate among microorganisms and autofluorescent particles. The four main discriminants are size, specific intensity, color ratio and signal pattern of the detected fluorescent spot...

Figure 7. Mean number of days (O ) and the standard error ( - ) to reach specified USDA color stage and a/b color ratio of four tomatoes packaged in two types of Cryovac film. The D-955 film package (surface area = 1007 cm2) an

Red, green, and blue cubic color model. The RGB Values are used in an additive way to describe a color. The color ratio varies from 0 % to 100 %. White is determined by 100 % of the three values. 

In the red wines the tannin content was not correlated with the color. The permanganate index, for example, varied from 4.7 to 12.9 with colors of 41 to 330. Rib4reau-Gayon and Maurie (1942) reported that wines with a high permanganate/ color ratio were more astringent than those with a low ratio. 

Koch, E.-C. (2007) Pyrotechnic countermeasures. Ill the influence of oxygen balance of an aromatic fuel on the color ratio of spectral flare compositions. Propellants, Explos., Pyrotech., 32, 365-370. 

The color temperature distribution over the whole field-of-view can be obtained with larcsec resolution om color ratios using various combinations of 3.8, 7.8, 12.4 and 20/ m array data. Figure 4 shows the color temperature distribution image from the de-reddened 12/20/xm brightness ratio. The highest color temperatures calculated from the 12/20/im image ratio... 

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