Question

What does the look-up table color filter do?

Answer

The color lookup table filter allows you to define the mapping of input to output pixel values for each color: red, green, and blue. This filter is like the standard lookup table with the exception that you can add or reduce emphasis by each individual color.

The lookup table uses a segmented line with three adjustment points you can drag to adjust the input to output pixel mapping for each color (red, green, and blue). Tabs at the top let you select the color affected.

The bottom axis represents input values while the left axis represents output values. A value of 0 is 100% red, green, or blue while a value of 255 is 100% white.

• The Reset Button adjusts the lookup table to have a one-to-one mapping between input and output values.
• The Brightness Buttons increase or decrease brightness by moving the lookup table adjustment points.
• The Contrast Buttons increase or decrease contrast by moving the lookup table adjustment points.
• The Gamma Buttons increase or decrease gamma by moving the lookup table adjustment points.

The lookup table is a powerful filter that can efficiently simulate complex operations.