computeGamma: Image Gamma Computation

In gitdemont/IFC: Tools for Imaging Flow Cytometry

Image Gamma Computation

Description

Computes image gamma transformation value.

Usage

computeGamma(V)

Arguments

V	channel display properties containing 'xmin', 'xmax', 'xmid' and 'ymid'.

Details

Thanks to http://www.libpng.org/pub/png/book/chapter10.html image_sample = light_out ^ gamma it is said that Once again, bear in mind that light_out and image_sample are scaled to the interval between 0 and 1; that is, if the sample depth is 8 bits, the file samples range between 0 and 255, so image_sample is obtained by dividing a given file sample by 255, in floating-point arithmetic. So, image_sample = ymid and its range is [0,255] light_out = xmid and its range is [xmin,xmax] we have ymid / 255 = ((xmid - xmin) / (xmax - xmin)) ^ gamma log(ymid / 255) = log((xmid - xmin) / (xmax - xmin)) * gamma gamma = log(ymid / 255) / log((xmid - xmin) / (xmax - xmin))

gitdemont/IFC documentation built on Feb. 20, 2025, 12:55 a.m.