[BUG] Auto Contrast still useless [1.0.1.10]

[thufor]

Auto Contrast seems to be running very early in the queue (definitely before Exposure), which makes it rather useless. This defeats the purpose of Auto Contrast rather spectacularly.

Example:

1. Choose a picture without shadows (e.g. high key).
2. Dial in negative Exposure (e.g. -0.7 EV).
3. Now apply Auto Contrast.

Result: totally underexposed histogram pushed well to the left.

[Tadjio]

What AutoLevel settings did you use?

[thufor]

Sensible ones ;-) 0.002 and 0.001. If you use Auto Contrast before applying Exposure compensation (omit step 2) it works ok. This points to Auto Contrast using histogram from very early stage in the queue. Auto Contrast should use histogram from very late in the queue, as it did in Bibble 5. ASP basically broke Auto Contrast.

[Tadjio]

Just curious - have you tested AutoLevel the same way?

[thufor]

No, not until now (since I don't use Auto Level...). I just tried and it looks like Auto Level is completely broken and underexposes even without negative Exposure.

[Tadjio]

I have tried to reproduce your scenario and I can't, either with Canon or Olympus Raw files.
Could you post screenshots of your image (with clipping) and curves histogram before and after?

Interestingly, AutoLevel appears just before Exposure in the AfterShot pipeline but no AutoContrast. Curves is almost last.

[gregglee]

Sensible ones 0.002 and 0.001. If you use Auto Contrast before applying Exposure compensation (omit step 2) it works ok. This points to Auto Contrast using histogram from very early stage in the queue. Auto Contrast should use histogram from very late in the queue, as it did in Bibble 5. ASP basically broke Auto Contrast.

Those were probably sensible for Bibble5 but since ASP is broken I decided to ignore what it "should" do and just experiment. For my equipment, with the new release, shadow .001 and highlight .02 work with auto contrast most of the time. Actually HL clip from .02 to .1 it pretty much the same. Note in B5 I used clips of .002 and .02.

The new release didn't fix the irregular "sticky" response to changes in clip levels, but the result of auto contrast and auto levels seems more reasonable than before, once you discover the clip settings for your equipment and tastes. (Many like a more aggressive clip than I do.) The new release is not back to Bibble5 performance, but of course B5 didn't get every image right either.