[ros-diffs] [gedmurphy] 24784: - merge the latest code from my minibranch: - use a static image to refer to when choosing your image brightness so returning to normal (100) displays the original colours - allow individual colours (RGB) to be adjusted as well as adjusting them all simultaneously - apply the chosen brightness from the dialog to the main image - implement greyscale, so an image can be displayed in black and white - implement inverting of colours so an image can be displayed as a negative.