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

Ch. 8 – Viewing, Editing, and Annotating ImagesTo Adjust Histogram (HSL) or Adjust Histogram(HSV), follow these steps:1. From the Edit menu, select Adjust HSL, AdjustHistogram or Adjust HSV, Adjust Histogram.The Luminance Histogram or Value Histogramwindow appears.2. If you want to display the image's histogramaccording to a logarithmic scale, check the LogScale box. Checking the Log Scale box makesthe vertical axis more sensitive to small numbersand compresses the range for larger numbers.From the Luminance/Value Histogram window youhave three viewing/editing options.• Examine the number of pixels at each Luminance/Value level.Do one of the following:−−Move the cursor along the graph to display the number of pixels at each Luminance/Value level.Type the same Luminance/Value level into both boxes under Number of Pixels. The histogramreadouts display the number of pixels at that Luminance/Value level.• Examine the number of pixels between two brightness levels.Do one of the following:−−Position the cursor over one luminance or value level on the graph, and left click and drag thecursor to the second Luminance/Value level. The histogram readouts display the number of pixelsbetween the two levels.Type the two Luminance/Value levels into the boxes under Number of Pixels. The histogramreadouts display the number of pixels between the two Luminance/Value levels.• Stretch the image.Follow these steps:a) Either drag the left triangle (on the X axis) to the Luminance/Value level that you want to define asblack (0 % Luminance/Value), or enter the Luminance/Value number in the Bottom box. AllLuminance or Value values that are less than or equal to this level are now reset to black (0 %Luminance/Value).b) Either drag the right triangle (on the X axis) to the Luminance/Value level that you want to defineas full scale (100 % Luminance/Value), or enter the Luminance/Value number in the Top box. AllLuminance/Value values that are greater than or equal to this level are now reset to full scale (100% luminance/value).The program automatically multiplies all Luminance/Value values between the new black and fullscale values by the factor necessary to make the new full scale value equal to 100 %Luminance/Value after the new black value (if you have defined one) has been subtracted. Thethumbnail sample image updates automatically so you can gauge the effect of your adjustments.c) Click on OK to save the image with the new black and white Luminance/Value values.152 User Guide to the SPOT Insight Camera