Histogram

The histogram window is responsible for assigning transformations from image original values (in any range) to palette range [0, 255]. The histogram curve will adjust any value smaller than the “From:” limit to 0, and any value greater than the “To:” limit to 255. Any other values will be mapped using the histogram curve to the “Y” coordinate on the color palette on the left.

Transformations

The default transformation doesn't map any values, leaving cell values “as is”.

Linear transformation will map linearly any values between the “from” and “to” ranges.

Equalize will construct a curve based on Equalization.