I then take a second exposure, using values that bring the red histogram back within reasonable range. I say reasonable because there may be spikes of red and yellow which are simply NOT capture-able (is that a word?) by your sensor. This looks like a pretty under-exposed image on the LCD, but I take it anyway.
When both images are opened in Camera Raw (or whatever software you use), there is visible detail in the darker one within the areas of red that were blown out on the original exposure. When I blend those two together, I have one image which maintains detail throughout.
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Red is a primary channel in the RGB colorspace, and so detail could potential be brought in by plate blending, and perhaps more precisely by plate blending a specific area, with either a generation of the black plate of an artificially created CMYK image, or with the luminosity channel of an LAB alternative of the image. Because only one channel is weak, this type of blending detail would work, where as it would not with say a yellow subject, where both the red and green plates are weak. So, even if you do not have an underexposed image, which is probably the best thing to have, you might be able to ressurrect the image.
ReplyDeleteWe never worked on this red flower, but recall that we did try that with another red flower (it was someone else's image) and we were not able to resurrect it. I think that our final conclusion was that if there is NO detail in the original channel, there is no way to recreate it retrospectively. Underexposing does increase the risk of noise, but may at least provide some detail with which to work. Thanks, Ray, for your insights!
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