Correction: Why photos converted by RPP look darker

I had the pleasure of hearing tonight from Andrey Tverdokhleb, developer of RPP, the outstanding raw converter that I wrote about here yesterday. I want to correct something I said yesterday and pass on a tip Andrey gave to me.

Why RPP’s output is darker

First, the correction. I commented yesterday that many of RPP’s conversions end up looking noticeably darker than conversions of the same raw file done by Lightroom. I made a guess — a bad guess — about why this might be so. I needn’t have guessed. Andrey draws my attention to an FAQ about RPP where this phenomenon is briefly explained. I know I had seen this page, but the info there hadn’t sunk in yet when I was writing yesterday.

The gist seems to be as follows: RPP is telling me the truth, while Lightroom (like most other raw workflow programs) is conspiring with my camera in a sort of lie or misrepresentation. I hasten to say that the camera makers and the software companies are lying to us for our own good. The cameras are calibrated to underexpose deliberately, in order to avoid blowing highlights. And the raw converters like Lightroom, knowing how the cameras behave, silently compensate by increasing the exposure value (moving the histogram to the right) so that pictures look properly exposed. RPP does not make this silent adjustment. So if your pictures look underexposed after RPP converts them, it’s because they really are underexposed.

The explanation in the RPP FAQ calls to mind a recent article by Michael Reichmann at Luminous Landscape titled “Optimizing Exposure” about how digital camera makers persist in metering exposure in a wrong-headed way. That article in turn harks back to Reichmann’s now classic “Expose Right” essay from 2003, one of the most important technical articles ever written for digital photographers.

I am still sorting out RPP but I am starting to think that it may make a change to the way I shoot, well, at least to the way I expose my photos. Maybe I will say more about this later when I feel more confident.

Getting the most out of RPP

The tip that Andrey gave me in tonight’s email is to be aware that certain things really need to be done right in RPP, before anything further is done in Lightroom. This tip could be considered a correction, also, because I said yesterday that you can just use RPP’s defaults and needn’t worry about the details. Sort of true. I mean, I did it and my first clumsy efforts with RPP were very satisfactory. But I see now that, for best results, I should be paying attention in RPP to more of those settings. Apparently white balance is the most important one to get right from the moment of conversion. I gather that I should be letting RPP handle as much else as possible, so that adjustments that a derived from the raw data get the benefit of RPP’s more accurate calculations.

(Posted using BlogPress from my iPad2)


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