Friday, July 25, 2008

Layer Masks for Increasing Contrast Range I


When I first noticed this Beautiful Wood Nymph (Eudryas grata) on the clematis leaf, I was immediately struck by the image, but knew that there would be an exposure problem. There is at least an 8 stop contrast range from the white on the moth's "shoulders" to the dark purple of the clematis. Your eyes can "see" approximately a 20 stop range of contrast, but modern sensors can record perhaps 7 or 8 stops at best, barely better than film.

If the petals and leaves were properly exposed, the white areas on the moth would be totally "blown out" and over-exposed. If, on the other hand, I exposed for the white areas, the remainder of the image would be grossly underexposed.

Photoshop to the rescue! I made 2 exposures, one with the white areas of the moth exposed for maximum highlight detail, and the other, a more "normal" exposure, for the darker tones. Both images were then brought into Photoshop and a layer mask was used to combine the correctly exposed highlights of one photograph with the darker tones of the other. The resulting image demonstrated the tonal and contrast range of the original scene, which could not have been captured in a single image.

This is a relatively simple technique which I consider a "bread-and-butter" tool. It involves use of the histogram in the field and a layer mask in Photoshop.

So, your question of the day is, "Is this cheating?"

3 comments:

  1. This is a fantastic technique! I don't think it is cheating.....

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  2. This is a fantastic technique! I don't think it is cheating.....

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  3. Neither do I, but some do. The only way around the conundrum is to be absolutely straight-forward about what you do and "let the editors decide" whether or not they find the technique acceptable.
    I've never NOT used a technique that I felt was appropriate for the image, but I have had images rejected for being "too manipulated".

    Remember, your eye sees 20 stops of contrast, your camera only about 5 to 8, at best. All this technique accomplishes is to show the range of contrast that your eye sees.

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