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

Ch. 8 - Viewing, Editing, and Annotating ImagesAdjust Gamma (HSL)Adjust Gamma (HSV)Like the Adjust Gamma (RGB) option, the Adjust Gamma (HSL) and Adjust Gamma (HSV) options allowyou to smoothly lighten darker areas of an image without burning out bright areas or lightening black areas.This is useful when modifying images with a wide dynamic range, meaning the range of brightness valuesrecorded by the CCD chip. Unlike the Adjust Gamma (RGB) option, Adjust Gamma (HSL) and AdjustGamma (HSV) work only on the luminance or value values (respectively) for an image as opposed to thespecific red, green, and blue values. Refer to Ch. 5 – Preparing to Take a Picture for a more detailedexplanation of gamma adjustment.To Adjust Gamma (HSL/HSV), follow these steps:1. From the Edit menu, select Adjust HSL, Adjust Gamma or Adjust HSV, Adjust Gamma.2. Enter a value between .1 and 4, or use the slider bar to select a value. The thumbnail preview of theimage changes as you adjust the value.−−To lighten the mid-tones of an image, enter a gamma value above one.To darken the mid-tones of an image, enter a gamma value below one.3. Click on OK. The new image appears on-screen.Stretch Bright and Dark Level (RGB)The Stretch Bright and Dark Level (RGB) option stretches the darkest level in an image to 0 (black) and thebrightest level to full scale. Full scale is 255 for 8 bit monochrome and 24 bit RGB images, and 4,095 for12 bit monochrome and 36 bit RGB images.Stretching the bright and dark level (RGB) for a 24 bit RGB image with a range of brightness valuesbetween 50 and 150 has the following effects:• The lowest value pixels (50) are stretched down to 0.• The highest value pixels (150) are stretched up to 255.This one-step process provides a quick and easy way to increase image contrast in low contrast specimens.To use Stretch Bright and Dark Level (RGB), select Adjust RGB, Stretch Bright and Dark Level from theEdit menu. The picture automatically adjusts itself.Stretch Bright and Dark Level (HSL)Stretch Bright and Dark Level (HSV)Like Stretch Bright and Dark Level (RGB), the Stretch Bright and Dark Level options in the HSL andHSV color spaces stretch the darkest luminance or value level in an image to 0 (black) and the brightestluminance or value level to 100 (pure white if Luminance/brightest version of hue if Value). Using theUser Guide to the SPOT Insight Camera 149