จากเทคโนโลยีภาพถ่ายดาวเทียม Decorrelation Stretch ขององค์การนาซ่า NASA สู่แอปแอนดรอยด์ Rock Art enhancer ของ Anthony Dunk นัก Software Engineer และ 

Decorrelation stretching enhances the color separation of an image with significant band-to-band correlation. The exaggerated colors improve visual interpretation and make feature discrimination easier. You apply decorrelation stretching with the decorrstretch function.

In pictograph images from Baja California, California, and Nevada I demonstrate its ability to bring out elements nearly invisible to the eye and to improve visualization of difficult sites. As such, the effectiveness of the decorrelation stretch analysis in producing enhanced displays depends fortuitously on the particular contrasts which result. For some examples, setting the first scaled principal component to zero before reversing the initial transformation has little effect on the decorrelation stretch coefficients. decorrelation stretchingIn remote sensing, a type of contrast stretchingthat results in the artificial enhancement in colour of an image. The spread of multi-spectral data is increased along the natural maximum as identified by principal component analysis. A Dictionary of Earth Sciences Principal Components can be stretched and transformed back into Rai colours — a process known as decorrelation stretching.

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Initially, the R, G, and B digital numbers (DNs) for each colour pixel are examined and the lowest value (it could be the red, green or blue) is selected. IHS_Decorrelation_Stretch_v16_6_1.gmdx In the provided model the user specifies which three bands represent data that is usually displayed as an RGB color composite. For true color aerial photography this would normally be 1,2,3, but may vary for other sensors. Decorrelation stretching enhances the color separation of an image with significant band-to-band correlation. The exaggerated colors improve visual interpretation and make feature discrimination easier.

J. Harman, “Using decorrelation stretch to enhance rock art images,” in Proceedings of American Rock Art Research Association Annual Meeting, Reno, Nevada, May 2005. View at: Google Scholar A. Uji, Y. Muraoka, and N. Yoshimura, “Hidden information in color fundus photographs is revealed by the decorrelation stretching method,” Retinal Cases & Brief Reports , vol. 13, no. 2, pp. 176

Decorrelation stretching enhances the color separation of an image with significant band-to-band correlation. The exaggerated colors improve visual interpretation and make feature discrimination easier. You apply decorrelation stretching with the decorrstretch function.

Another way to enhance the truecolor composite is to use a decorrelation stretch, which enhances color separation across highly correlated channels. Use decorrstretch to perform the decorrelation stretch. Specify the optional name-value pair 'Tol',0.1 to perform a linear contrast stretch after the decorrelation stretch.

The three-stage decorrelation stretch analysis—transformation to principal component scores; contrast-stretching of the scores to equalise the variances; and reversal of the initial transformation—is shown to produce linear combinations of the original bands which are uncorrelated and have unit variances. and reading from right to left, you can see that the decorrelation stretch: Removes a mean from each band Normalizes each band by its standard deviation (correlation-based method only) Rotates the bands into the eigenspace of Corr or Cov Applies a stretch S in the eigenspace, leaving the image The image with the various colors was created with a technique called Decorrelation Stretch (DCS). In this technique individual bands of the THEMIS IR instrument are stretched to better show compositional variations throughout the whole range. Some imagery.

Find the decorrelation times for a 10-cm and a 5-cm radar wavelength if the spectrum width is 1 m s −1. 6.2. A power transfer function of a receiver is given by Q = α log β P where Q is the output and P the input and α, β are constants. Note You can apply a linear contrast stretch as a separate operation after performing a decorrelation stretch, using stretchlim and imadjust.This alternative, however, often gives inferior results for uint8 and uint16 images, because the pixel values must be clamped to [0 255] (or [0 65535]).The Tol option in decorrstretch circumvents this limitation. Decorrelation stretching enhances the color separation of an image with significant band-to-band correlation. The exaggerated colors improve visual interpretation and make feature discrimination easier.
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This is an image enhancement technique first used on aerial photos. For an explanation of how it works see the algorithm description. DStretch is a tool for rock art researchers who wish to enhance images of pictographs.

The number of color bands, NBANDS, in the image is usually three. But you can apply decorrelation stretching regardless of the number of color bands.
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Decorrelation stretch is used to enhance color differences in images with high interchannel correlation. Therefore it allows us to see details that are otherwise not so obvious or invisible to the human eye. I first came across decorrelation stretch in a Matlab webinar and was curious to find out how it works.

Its intended  Decorrelation is a general term for any process that is used to reduce autocorrelation within a This is generally termed as 'decorrelation stretching'. Examples of images enhanced by conventional linear stretches, decorrelation stretch, and by stretches of HSI transformed data are compared. Schematic. Figure 6 shows Decorrelation stretched image displayed in RGB colour composite for bands 1, 2 and 3 of ASTER. The results show that Decorrelated image can  Decorrelation stretch image of ASTER spectral bands 8, 3, and 1 showing the occurrence of the Huqf Super Group formations (Masirah Bay-Mf; Khufai-Khf;  I. Decorrelation and HSI contrast stretches histograms are used to illustrate the “decorrelation stretch” method and the effect of the different enhancements. 31 Jan 2019 Decorrelation stretching is a useful technique for highlighting parts of images that might not otherwise be obvious.