I guess I’ll be the first one to take a stab at this. Since AE still hasn’t updated all their plugins to 32bpc, we’ve been stuck with a conundrum. Some effects give warnings but can be somewhat protected if you use utility->hdr compander.
Think of bracketing your 8,16 warnings with 1 at the very top set as-compress range and one at the bottom set at -expand range. You can take a screenshot and compare how the compander protects color.
As for why we should ever use 16 bit if we only output milllions+ 8bit anyway, is because AE will preserve posterization calculations then spit out correct 8 bit again.
As for 32bpc, you can push,pull pixels to your hearts delight and some effects are even redundant and can be replaced, like shift instead of set channels, hue/sat instead of color hls, transfer modes instead of calculations are 32bpc.
Should I go 32bpc all the time no matter what? I haven’t seen any reasons not to if you use compander as needed. This way you can use Color Finesse onto hundreds of precomps and not worry about posterization.
The only downside I can think of is really old plugins may not work even with compander and really large images, if you don’t have enought RAM, could give you a image buffer error. 8 bit is so 1980’s.:)
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