Luminous Landscape Forum
Raw & Post Processing, Printing => Adobe Lightroom Q&A => Topic started by: kevk on June 06, 2011, 09:27:04 pm
-
I've scanned a bunch of negatives to TIF using ViewScan, imported them into LR 3.4.1 and am using the Develop tools to fix them up.
When using the White Balance Selector in Develop, I get something happening that I have not seen before (I've been using LR since it came out, but mostly on raw files from a DSLR).
Note that I have not opened these TIFs previously with Bridge or Photoshop - only imported them into LR.
"Sometimes" when I click on an image with the White Balance Selector I get the following behaviour:
- WB: changes from "As Shot" to "Custom" (expected)
- The temp and tint do not change (unexpected)
- History shows the words "Camera Raw Settings" (unexpected - should be "White Balance: Custom")
After some experimentation, it seems to always happen when the point I click on has at least two of the RGB percentages in the high 90's - e.g. the point I clicked on just then was 96.3, 98.4, 89.0 and it did the "Camera Raw Settings" described above. If all values are less than high 90's, or only one is in the high 90's I get the familiar white balance adjustment.
e.g. clicking on:
- 74.8, 67.2, 57.3 does the right thing.
- 88.4, 90.3, 83.2 does the right thing
- 99.6, 99.7, 93.7 does the unexpected thing
- 94.5, 96.9, 89.3 does the unexpected thing
Is this something new, or has it done this all the time and I never noticed?
Kevin
-
The LR white balance eyedropper tool uses a fixed (non-adjustable) sample size of 5x5 (25 pixels), regardless of the loupe size setting. The white balance reading is the "average value" of these 25 pixels summed together. My guess is if any one (1) of those 25 pixels is at 100% RGB value, LR rejects using the sample. This is probably why there is no change to the white balance with the high 90s samples, but I can't explain the History entry as 'Camera RAW'. What do you normally see with TIFFs in the History panel when making white balance corrections with the eyedropper tool?
-
Hi trshaner,
Interesting thought.
>>> What do you normally see with TIFFs in the History panel when making white balance corrections with the eyedropper tool?
As I said - "White Balance: Custom"
Kevin
-
The LR white balance eyedropper tool uses a fixed (non-adjustable) sample size of 5x5 (25 pixels), regardless of the loupe size setting. The white balance reading is the "average value" of these 25 pixels summed together. My guess is if any one (1) of those 25 pixels is at 100% RGB value, LR rejects using the sample. This is probably why there is no change to the white balance with the high 90s samples, but I can't explain the History entry as 'Camera RAW'. What do you normally see with TIFFs in the History panel when making white balance corrections with the eyedropper tool?
I'd go a bit further with this line of thought: A WB correction is done by boosting the red and blue channels relative to the green. If the sampled levels are so high that the red and/or blue values would be pushed to clipping, LR won't do the operation and the caption "Camera Raw Settings" indicates that the WB performed at the time of conversion from RAW has remained unchanged.
-
It's pretty clear one of these possible issues is causing the problem when you see the 'Camera RAW' entry after using the white balance eyedropper, and no change in white balance setting (0,0). Personally I have never had this problem, but I always select a sample that is well below clipping. I know the "school of thought" is to select an area with a high signal-level (white), but my results are always better using a sample area in the 80% to 90% range.
You may want to read this post at Adobe LR Forums for a lively discussion on the white balance eyedropper tool:
http://forums.adobe.com/message/3702964#3702964
-
It's pretty clear one of these possible issues is causing the problem when you see the 'Camera RAW' entry after using the white balance eyedropper, and no change in white balance setting (0,0). Personally I have never had this problem, but I always select a sample that is well below clipping. I know the "school of thought" is to select an area with a high signal-level (white), but my results are always better using a sample area in the 80% to 90% range.
You may want to read this post at Adobe LR Forums for a lively discussion on the white balance eyedropper tool:
http://forums.adobe.com/message/3702964#3702964
Thanks for the link. Always a good read when Andrew is involved.
-
Thanks for the link, trshaner. Very interesting.
Kevin