Bug fix release 21.5-Apr-2018

[jsachs]

I have posted a new release (21.5-Apr-2018) in executable-only. Minor edits to help file to describe histogram entire image/masked area only feature in Brightness Curve and Color Curves.

The changes (taken from the update log) are:

Fixed problem with toggle bypass in image browser not always working.

Added option to the Brightness Curve and Color Curves transformations to histogram entire image or just the currently masked area. Interface refinements and extension to other tools and transformations to come.

Fixed bug making it impossible to save 24-bit color images as JPEG.