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Adobe Photoshop Family

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Sun, May 27, 2012 5:37 AM


Lightroom 4.0: Auto-tone suggestion to handle bright spots & resulting under exposure

There is a suggestion in some forums that specular high-lights or light sources (lamps, head-lights, etc) adversely impact auto-tone in version 4 of Lightroom resulting in under-exposure.

Just an idea on how to handle it. I suspect PV2012 "Auto-Toning" finds the brightest area performs great highlight recovery on it (whether it should or not) and reduces the exposure of the rest of the photo in some fashion. The highlight recovery on this brightest area probably ignores how much of the image is near bright in relation to the brightest point or the wieghting given to it is low.

If this is correct, maybe the answer is Autotone has to determine how much of the image is very bright (size of histogram at that point) versus how much of the image is near bright, and so on down the histogram of image. Using some weighting measure you can:

1) not recover (or severly limit) as it is specular or a light (small area very bright, not much is near bright)

2) give a decent attempt to recover as with clouds or wedding dress shots (small to medium area very bright, fair amount of image near bright), or

3) give a strong attempt to recover as with snow shots (if medium or greater area very bright, large portion of image near bright).

Finally, given the reduction of exposure somehow "follow's the lead" of highlight recovery, exposures should be closer to expected.

- sb

ps: This approach (and of course the current auto-tone analysis of the image) would be partly / wholly fooled by the borders of scanned photos (the ones where they were printed with white borders). Only suggestion I have is to allow auto-tone to perform the image analysis post-crop.


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