LED - uniformity issues

Quite a few LEDs emit too much red. I will need some sort of dot correction to compensate ;-(

8 out of 10 boards have issues.

The manufacturer recommended using drivers that support dot correction. Also they don't check/sort the chips with respect to emittance before assembly. DUH! I wonder why all the other boards I got from them before were perfectly OK.

I implemented dot correction to the latest firmware of my controller, but it costs some speed. The dot correction is stored in PROGMEM and the reads seem to be somewhat slow. I'm also facing a few casts back and forth between int8_t and unit8_t which also takes time.

I think I'll have to rewrite the framebuffer code to allow gamma correction as well. Currently a single run of the ISR refreshes the full display and blocks other stuff for about 50% of cpu time. A rewrite to just do one intensity level per ISR run would spread the load more evenly and may be better for other jobs like I2C and serial.

For dot correction on driver level I'd have to switch some chips. No time for that right now. Getting flawless LED boards would be much better.