SPOT 4.1 Basic and Advanced Software Manual for SPOT Insight ...

Ch. 8 – Viewing, Editing, and Annotating ImagesHSL or HSV (for fluorescence images) color space to stretch images, as opposed to the RGB color space,reduces the potential for washed out images and color shifts.To stretch bright and dark level HSL or HSV, select Adjust HSL, Stretch Bright and Dark Level or AdjustHSV, Stretch Bright and Dark Level from the Edit menu. The picture automatically adjusts itself.Adjust Histogram (RGB)A histogram is a graphical representation of the number of pixels at each brightness level in an image.SPOT’s histogram displays the red, green, and blue histograms on the same graph. It serves two mainpurposes:• It is a point of reference for examining the distribution of brightness levels for the red, green, and bluecomponents in an image.• It can be used to reset the zero and full-scale points for an image. This is known as stretching. Likethe aforementioned Stretch Bright and Dark Level function, the Adjust Histogram option enables youto stretch the darker areas of your image to pure black and at the same time lighten the brighter areas ofthe image.Note: Full scale for 8 bit monochrome and 24 bit RGB images is 255. Full scale for 12 bitmonochrome and 36 bit RGB images is 4,095.To adjust an RGB histogram, follow thesesteps:1. From the Edit menu, select Adjust RGB,Adjust Histogram. The RGB Histogramwindow appears. Set the displayparameters for the histogram:−Determine the color or colors that youwant to display brightness values for.As a default, the histogram displays allthree values. To display a differentcombination of colors, deselect theShow box for the unwanted color(s).−To display the histogram according toa logarithmic scale (as opposed to alinear scale), check the Log Scale box.This makes the vertical axis moresensitive to small numbers andcompresses the range for larger numbers.150 User Guide to the SPOT Insight Camera