Having worked through the new tutorial several times, documenting my work to catch mistakes and verify when I got it right, there’s a couple items I thought I would bring up for discussion. Before I do that, when I completed the tutorial, I was very pleased with the results—they matched, as far as my untrained eye could see, the after images in the tutorial. Thank you very much, Elle. I’ve really learned a lot.
First, just to mention that on step B.3.4, Figure 7. indicates that Auto Stretch Contrast (ASC) is used, but the text does not mention it. I tried it both ways and compared the histogram against the one in Figure 8. There’s a fair amount of difference between the two histograms of with and without ASC, and it seems to me that the one when ASC was used matches the histogram in Figure 8.
In step C.2.3, it says, “A layer mask is used to avoid blowing out the brightest portions of the sky.” The layer mask, Mask for Curves for sky, includes a selection. The text does not indicate that the selection be applied to the image, but I assumed that it should be because an important goal was to prevent blowing out the lower left portion of the sky. Therefore, sample points 2 and 3 should not, I think, change when the curve is applied because they are outside the selection area. However, when I completed this step the RGB readings for all three sample points changed.
C.2.3 Mask for Curves for sky
C.2.3 Before:
C.2.3 Curve application:
C.2.3 After:
All three sample points changed.
Similarly with step C.2.4, the sky is to be protected from the curve application:
C.2.4 Mask for Curves for ground (from Blue Channel)
C2.4. After curves application
None of the sample points should have changed, but 1 and 3 did.
In both cases, I tested the selection usage by creating my own selection area that was roughly the same as the tutorial’s, and in both cases, the sample points behaved as expected.
Masks
I’ve already shown two of the masks used, not counting the Chroma mask. I wanted to figure out how they were made, as they are extremely important to managing clipping. I tried out the method given by Pat David in a tutorial on Luminosity Masks, using luminance instead. What I was especially interested in determining was how to get the tonal variations in the sky. However, none of the luminance masks I produced revealed the variation found in Elle’s mask.
The mask for ground cover indicated in its name that it was from the blue channel. Below in the blue channel I pulled from the image after step C.2.3. I am puzzled as to how the mask shown above was made from that.
This is C.2.5 Mask for High pass. Just guessing: came from green channel, used curves to darken and then selected the dark areas, saved the selection, used curves to get the tones in the trees, applied the selection, filled with black, sharpened in some way. ???
Referring back to the sky mask, I can get close to getting the white areas, but the tone and, in particular, the tonal variation in the grey area, how was that done and how was the variation decided upon?