EM-5: Confused by Auto White-Balance results

Started Feb 12, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,683
Re: Auto White Balance is magic, and magic can go wrong ...

Timur Born wrote:

Thanks for the links, DM. Interesting stuff! But does that mean in practice that it's illusionary to expect similar outcome when shooting similar scenes with different lenses or flash even the target/image colors are still the same?

It sounds like it may well be if it is indeed the case that cameras are but a "juke box" of pre-programmed "canned" WB settings that the system "lurches" between based on some rather crude measurments made using the RAW-level RGB channels.

Iliah Borg likely "knows his stuff" on that. I came out of those investigations with far less trust in Auto WB schemes than many users seem to have. Indoor lighting with tricky skin-tones is likely to be much harder than outdoor naturally lit environments.

Have found that even a rough Custom WB calibration to an indoor (even mixed artificial/natural) lighting environment can get one closer that Auto WB may. However, I am not talking about portraits with caucasian skin-tones, etc.

Have you tried (rough) Custom WB calibrating (as opposed to Auto WB) ? I wonder if it might (sometimes) serve you better with WB Temp/Tint "starting-points" ?

I do very little RAW processing with portraits and caucasian skin-tones. In what I do (nature/landascape stuff), I usually find that simply centering the Tint, manually adjusting the Temp to get close, and then some fine-tuning of the Tint (with perhaps some small amount of interactive adjustment together with Temp) works well (to my eyes, for what I photograph).

I don't find (with my GH2) that I ever use Tints greater than -2 to +2 when processing with DxO Optics Pro 7.x. Two (2) in either direction can be plenty (if not too much) in producing Green or Magenta tinting that is not desirable. I usually use no Tint at all (unless necessary).

As you know, the Adobe applications use higher numbers (allowing for more resolution) in their Tint adjustment controls. Not aware of how they correspond to DxO numbers (but they always seem to be many multiples larger in numerical value in LR 3.6). RAW Therapee (as you must know) seems to be nuetral at +1.000 (lower values Green, higher values Magenta, I think).

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