Improve image quality in Chrome (Gradient banding)

[rmscode]

I tried fixing this “issue” in the past but got busy with other things. I had actually mentioned the solution in my original post without knowing it, but it slipped through the cracks I guess and was forgotten about until now.

The file /etc/chromium.d/dietpi contains a set of flags that the DietPi devs thought would be useful (they are). One of them being --enable-low-end-device-mode. This will force Chrome to use 16bit color instead of 24, among other things. Removing that flag improved the quality of images displayed in Chrome. I haven’t noticed any performance issues yet, but we use our Pis to display static web pages, so your mileage may vary.

See below:

[MichaIng]

Probably it is time to skip those flags. Chromium is anyway not usable anymore on Raspberry Pi 1 and Zero models, since they lost ARMv6 support. And the 2nd slowest SBCs (Raspberry Pi 2 and Allwinner H3 boards) are already multiple times faster. And most of the flags do not exist anymore or are redundant:

• low-res-tiling removed with Chromium 140: [//cc] Remove remaining low-res tiling refs in PictureLayerImpl test · chromium/chromium@f7f191f · GitHub
• num-raster-threads seems to default to the number of CPUs already: chromium/content/browser/gpu/compositor_util.cc at f438ebed41ce27d2d719e5c2ce85b947d0415da7 · chromium/chromium · GitHub
  This fact is verified in chrome://gpu, where I see “Multiple Raster Threads: Enabled” as of Issue 519923002: Make the number of raster threads appear in chrome://gpu. - Code Review.
• Disabling composited-antialiasing was not so much about saving CPU/power, but that it caused artifacts in some cases, in the past: CC: Add command-line flag to disable AA. · chromium/chromium@7205ba4 · GitHub
• Disabling smooth-scrolling was similarly for issues macOS unit test environments: https://github.com/chromium/chromium/commit/678e68a
• --no-sandbox is needed for the root user to start Chromium, and --test-type is needed to mute the warning about this flag being used. But we should apply this for the root user only, not when any other user runs it.

Generally, those experiments/flags are for testing and debugging, not meant for production, especially not as defaults without knowing the Chromium version, platform, and why a flag is needed/beneficial in a certain case.

This should do: dietpi-software: Chromium: update flags · MichaIng/DietPi@eb769e1 · GitHub

@rmscode would be great if you could give it a try:

G_SUDO G_EXEC eval 'echo '\''[ "$(id -u)" -eq 0 ] && export CHROMIUM_FLAGS="$CHROMIUM_FLAGS --no-sandbox --test-type"'\'' > /etc/chromium.d/dietpi'

Maybe you spot some positive difference regarding finer antialiased edges and smoother scrolling.

[rmscode]

If I am able to remember, I will try this out and report back. Primarily, I “play around” with Raspberry Pis at work and by the time I am done with work I’m too tired to play at home .