### Problem description

Most of the time my workflow consists in a black window (terminal or text-editor) and a white one (web browser), so any brightness level is either too dim for the dark windows or too shiny for the browser, thus effectively I have to repeatedly

* lower brightness when going from terminal → browser.
* increase brightness when going from browser → terminal.

Clearly this is very frustrating.

### Failed attempts

I have Redshift running but it does not eliminate the problem.

Using browser extensions to darken webpages turns out not to be an option since many webpages become unreadable.

I have only one monitor, so I cannot keep dark windows in monitor X and bright ones in monitor Y.

[Similar question on Ask Ubuntu](https://askubuntu.com/questions/1143423/have-different-brightness-for-different-workspaces) but no response.

### Requirements

**Ideal**

The software would automatically detect if the window is bright or dark and adjust its brightness accordingly, so that it could even deal with a split screen with one bright and one dark window.

**Acceptable**

* The software would operate on individual workspaces, so that I could set higher brightness on a workspace where only dark windows would be spawned; or
* The software would scale the RGB components of each screen pixel by a fixed factor, say `0.7`. So `#000000` (black) would still be black, `#3B3B3B` (gray) would be mildly darkened to `#292929` and `#FFFFFF` (white) would be harshly darkened to `#B2B2B2`; or
* Something similar.