Exposure control in a raw developer: misnomer?

Started Jan 30, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,681
Re: Absolutely correct.

panos_m wrote:

Detail Man wrote:

gollywop wrote:

panos_m wrote:

gollywop wrote:

Well, there is a distinction to be made. In the earlier days of ACR, Exposure was basically an ISO slider that essentially multiplied all values by a given amount, altering all values in the same proportion (and quite able to blow out highlights). The "brightness control," by contrast, boosted the mids while holding the ends fixed; it was more nearly like taking a "curves" and lifting the center.

Raw converters like RPP have a Compressed Exposure slider that multiplies the exposure values up to a point, but compresses the highlights in the top, say, 2 EV to keep the highlights from clipping.

Nowadays, ACR doesn't have a "brightness" control in the sense of above, but you can achieve the same end in a number of ways.

So, rather than call the "exposure" control Rendered Brightness, I'd rather see it called ISO, or gain, or Exposure Multiplier. It clearly increases the brightness of the image (and doesn't in any way affect the image's actual exposure), but it doesn't protect the highlights, which is what a "brightness" control ought to do.

LR4s (and I assume latest ACR) exposure slider is not a linear adjustment. So it is still some kind of curve - brightness adjustment control. So it cannot be called a software ISO control.

This is true. But the current LR/ACR exposure control still affects all levels, more or less proportionately, except that there is a bit of a roll-off at the high end to provide some (but by no means complete) protection of the highlights. ISO still comes closer than "exposure," but I would still prefer Exposure Multiplier.

Have you tried testing it using the DNG RAW-levels test-chart that exdeejjjaaaa recently posted:


I used the file provided here: http://forums.dpreview.com/forums/post/50706883 by Iliah Borg.

The test DNG image-file is the same in both cases.

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