AcrCalibrator with ACR 5.x / CS4 & DNG Profile Editor

[merg]

Hi, just recently updated CS3 to CS4 and started using a Canon D50. Now, I want to check the Calibration with AcrCalibrator (like I did with the D30 before), but noticed that the script AcrCalibrator, hasn't been updated in a while. Does it still work with the latest ACR and CS4?

Also quickly checked out the DNG Camera profiles. There you can also use a photo of a ColorChecker chart, but this doesn't change the color matrices. I think I'm mixing 2 different things up here.  

[JeffKohn]

The old calibration scripts are no longer necessary, the DNG Profile Editor is the way to go. You won't see changes in the Calibration tab with this approach, but it _does_ affect the color matrices. The new profiles are better, and faster/easier to create as well, plus you get the benefit of being able to easily customize them.

[Eyeball]

Agree completely with Jeff.  The Profile Editor does a great job and is both faster and more consistent than the scripts.  Nothing against Rags, Fors, and the others - it was a limitation of Adobe's color process at the time - but I could run those scripts 5 times and get significantly different results each time.  Also, due to the earlier Adobe method at that time, even with the scripts it was virtually impossible to get subtle tones like skin and saturated reds correct at the same time.

With Profile Editor I can run it twice on the same chart and get nearly identical results.  The colors are more accurate now across all saturations (my reds are still slightly hot but much better than before - could be my mistake).  Skin comes out great.

[merg]

Thanks all for explaining this; it's indeed way faster. Just exported the profile. This DNG profile editor looks very promising.

[JeffKohn]

The nice thing about the new editor, is that once you create your base profile using the CC24 test image, you can create different "flavors" of that profile that are tweaked for certain preferences or image types. For instance I have a "landscape" profile that shifts foliage a bit more towards bluish green, since that's what people are used to seeing in photos and I find it more pleasing than the yellowish foliage that my base profile would give me (even though the latter is more colorimetrically accurate). You could also have a profile to tweak skin tones in portraits if you wanted.

[madmanchan]

That's right, Jeff, and it was one of the primary design reasons for having the "base profile" setup in the DNG Profile Editor. You can start from any given profile and then make a few edits relative to that baseline.

[b2martin]

The DNG profile editor requires a DNG file of the 24 patch color checker at 6500K and 2850K light sources to calibrate the profile.  What is recommended for these two different light sources?  

Is direct sunlight acceptable for the 6500K image and tungsten light for the 2850K light?

[Eyeball]

Is direct sunlight acceptable for the 6500K image and tungsten light for the 2850K light?

That is correct.  If shooting the target outdoors in sunlight, try to avoid anything that would throw off the color (a red wall nearby, lots of green grass, etc.).

If you are in a hurry, one target in daylight is better than nothing.  I find my daylight target does a reasonable job for tungsten also, although certainly not as good as using both.

Some people also create specialized profiles, which have been shot under other types of lighting - florescents, for example.  This could be useful if you shoot often under those circumstances.

[madmanchan]

Is direct sunlight acceptable for the 6500K image and tungsten light for the 2850K light?

Yes, though as Eyeball noted, do try to avoid color casts from nearby objects.

[b2martin]

Thanks for the inputs.  I was concerned that direct sunlight might be wrong since the white balance slider is in the 5500K range with ACR for daylight.  I always wait until mid day to photograph the 24 patch color checker for use with the DNG profile editor.

[madmanchan]

In practice there is very little difference in camera color response when photographing under actual daylight whose CCTs range from 5000 K through 6500 K (often higher). However, note that the use of the term "actual daylight" is important here, as it is the actual spectrum of the light source that is important. There can be (and often are) significant color response differences when using so-called "full spectrum" bulbs with CCTs in the same range.

[b2martin]

Would you expect to see much differenct between using "Actual Daylight" versus "Flash"?

I have noticed a lot of difference when using the white balance eye dropper in ACR for a Lastolite gray reference in "Actual Daylight" versus "Flash". but don't see as much difference with the WhiBal Card or 24 patch color checker.  The WhiBal Card and 24 Patch Color Checker Gray gives almost identical results for each light source (different between the two light sources), but Lastolite gives much warmer results in flash than actual daylight and does not agree with WhiBal or 24 patch color checker.

[madmanchan]

Yes, I would expect to see more of a difference between real daylight and a flash.

Regarding the WB differences you're seeing, that's likely due to a non-flat spectral reflectance of the Lastolite. The result is that under one illuminant (e.g., daylight) it can appear the same to the camera as the other two (the WhiBal and light gray patch of the CC 24, row 4, column 2 -- are spectrally quite similar), but can appear different under another illuminant.