Lookup Table

Improves contrast and brightness by applying a lookup table to an image. A lookup table (LUT) contains values used to transform the grayscale values of an image. For each grayscale value in the image, the corresponding new value is obtained from the LUT and assigned to every pixel of that grayscale value. The following controls are available.

• Step Name—Name to give the step.
• Lookup Tables
  • Image Source—Opens the original input image.
  • Equalize—Increases the intensity dynamic by distributing a given grayscale interval [min, max] over the full grayscale [0,255]. This function redistributes pixel intensities in order to provide a linear cumulated histogram.
  • Reverse—Reverses the pixel values, producing a photometric negative of the original image.
  • Logarithmic—Applies logarithmic transformation on the image pixels, which increases brightness and contrast in dark regions.
  • Exponential—Applies an exponential transformation on the image pixels, which decreases brightness and increases contrast in bright regions.
  • Square—Reduces contrast in dark regions. Similar to Exponential but with a more gradual effect.
  • Square Root—Reduces contrast in bright regions. Similar to Logarithmic but with a more gradual effect.
  • Power X—Reduces contrast in dark regions.
  • Power 1/X—Reduces contrast in bright regions.
• Power Value—Value of the power X for the Power X and Power 1/X functions. Default value is 1.5.