Visual Perception

For easy readability of black text on a coloured background it requires the colour background provides adequate contrast.

Colour perception for the DCP panel has created some difficulties in maintaining simple traffic light colours due to colour perception by the human eye.

For example pure red is too dark for easy readability of black text. In order to make black lettering stand out the red needs to be lightened by adding additional colours.

The above image shows various colouring red options with the second option having the greatest readability with black lettering.

The calculation of optimal colouring is based on the following formula which calculates the luminance of any colour based on RGB components registration with human vision.

  double luminance = (0.299 * color.R + 0.587 * color.G + 0.114 * color.B) / 255;

To Get an optimal colour for black text the calculated luminance is required to be greater than 0.5.

This allows sufficient contrast to maintain readability.

Green is easy and blue is harder to get an optimal colour due to the low perception by the human eye.

An additional requirement for the DCP panel is to maintain focus on RED>YELLOW>GREEN. IE. make the red stand out as appearing brighter than less prioritised colours.

This requires differing approaches for dark mode compared to light mode.

Hope this goes some way to explaining the new colour choices in DCP panel.

AK