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

Ch. 8 - Viewing, Editing, and Annotating ImagesFrom the RGB Histogram screen you have three viewing/editing options.• Examine the number of pixels at each brightness level.Do one of the following:−−Move the cursor along the graph to display the number of pixels with red, green, and blue valuesat each brightness level and the total number of pixels at that level.Type the same brightness level into both boxes under Number of Pixels. The histogram readoutsdisplay the number of pixels with red, green, and blue values at that brightness level, as well as thetotal number of pixels at that level.• Examine the number of pixels between two brightness levels.Do one of the following:−−Position the cursor over one brightness level on the graph, and left click and drag the cursor to thesecond brightness level. The histogram readouts display the number of pixels with red, green, andblue values between the two brightness levels as well as the total number of pixels.Type the two brightness levels into the boxes under Number of Pixels. The histogram readoutsdisplay the number of pixels with red, green, and blue values between the two brightness levels, aswell as the total number of pixels.• Stretch the image.Follow these stepsa) Either drag the left triangle (on the X axis) to the brightness level that you want to define as zero, orenter the value in the Bottom box. All red, green, and blue values that are less than or equal to thislevel are now reset to zero.b) Either drag the right triangle (on the X axis) to the brightness level that you want to define as fullscale, or type in the value in the Top box. All red, green, and blue values that are greater than orequal to this level are now reset to full scale.The program automatically multiplies all red, green, and blue values between the new zero pointand full scale values by the factor necessary to make the new full scale setting equal to actual fullscale after the new zero point setting (if you have defined one) has been subtracted.c) Click on OK to save the image with the new zero point (Bottom) and full scale (Top) values.Adjust Histogram (HSL)Adjust Histogram (HSV)HSL and HSV histograms are identical to RGB histograms, except that instead of displaying the number ofpixels for the RGB components, they display the number of pixels at each luminance or value level. Aswith the RGB histogram, HSL and HSV histograms are typically used for two purposes:• Examining the distribution of luminance or value levels in an image.• Resetting the zero and 100 % luminance/value points in an image. This is known as stretching. TheAdjust Histogram (HSL) and Adjust Histogram (HSV) options allow you to stretch the darker areas ofyour image to pure black and lighten the brighter areas to either pure white, if using the HSL colorspace, or the brightest version of the hue, if using the HSV color space.User Guide to the SPOT Insight Camera 151