[evince] Low Contrast

[Drew <soldier9599 gmail com>]

"Inverted colors" mode is indispensable, but bright white text against a black background is hard to read. White light leaves a bright positive afterimage on your retina for nearly a second, which means you have character afterimages following your eye around as it moves, creating a great deal of visual noise as old text is superimposed over desired text. This visual noise disrupts the desired character image, making text less readable.

Black text on a white background does not have this problem since it takes a long time to adjust to darkness, and it does not leave a lasting impression. If it did, every blink would have a significant negative effect on your overall vision, similarly to if a bright light were flashed into your entire field of vision. Light causes an immediate adjustment and intense residual afterimage. A broad white background tends to fairly evenly excite all retinal cells within a large region, and the black letters cannot overcome its influence enough to leave significant positive afterimages. This does not interfere with character recognition because it simply affects the brightness of an entire region rather than introducing random noise.

Many inversion tools, such as the Deluminate Chrome extension, have a "low contrast" feature. For those of you who code against dark backgrounds, I'm sure most of you, like myself, don't use a totally black background with bright white text. More common is a grey or slate blue background with light but not bright white text. Whether the developers of these color schemes realize it or not, this precedent exists precisely for the reason I am describing. The reduction in contrast reduces the letter afterimage duration, causing a significant reduction in visual noise and character disruption.

Adding a low contrast feature to Evince to be used with "inverted colors" mode will improve text readability.