# Image Enhancements

You have your choice of these image enhancements:

  Clipboard as CLUT
    use the clipboard image as a color lookup table.
  Spiff
    enhances the intensity differences between the lighter and darker elements of the image.
  Dull
    reduces the intensity differences between the lighter and darker elements of the image.
  Contrast Stretch
    improve the contrast in an image by `stretching' the range of intensity values. A good starting point is a 1% black and white point (e.g. 1%).
  Equalize
    perform histogram equalization on the image.
  Normalize
    transform image to span the full range of color values.
  Negate
    replace very pixel with its complementary color (white becomes black, yellow becomes blue, etc.).
  Hue
    vary the percent hue of the image (0-200%).
  Saturation
    vary the percent saturation of the image (0-200%).
  Brightness
    vary the percent brightness of the image. Reasonable values extend from 50 (darker) to 150 (brighter).
  Gamma
    level of gamma correction. The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference. Reasonable values extend from 0.8 to 2.3. You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delineated with slashes (e.g. 1.7/2.3/1.2).
  Level
    adjust the level of image contrast. Give three point values delineated with commas: black, white, and mid (e.g. 10%,90%,1.0). The white and black points range from 0 to 100% and mid ranges from 0 to 10.
  Linear Stretch
    linear with saturation stretch. Give two point values delineated with commas: black, and white (e.g. 10,90%). The white and black points range from 0 to 100%.
  Sigmoidal Contrast
    sigmoidal non-lineraity contrast control. Give two values contrast and midpoint. Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. Contrast indicates how much to increase the contrast (0 is none; 3 is typical; 20 is a lot); mid-point indicates where midtones fall in the resultant image (0 is white; 50% is middle-gray; 100% is black). A good starting point is 3x50%.