Creating Raw Tone Curves for Panasonic compacts

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Creating Raw Tone Curves for Panasonic compacts

I was working on creating a Raw Tone Curve template for the Panasonic G3 and GX1 (identical sensors), and I ran into the same problem that I'd had with the Raw Tone Curve template for the GF2. I was getting inconsistent results. Specifically, I'd calibrated (as I usually do) against the Q13 chart in DPReview's studio scene Raw file. But when I loaded up other sample Raw files from that camera model, they had way too much contrast.

Looking at the preview images in the LZ Browser, which are generated directly by dcraw, I see that the DPReview studio scene looks flat. This seems to be the immediate cause of my problems: I'm calibrating the Raw Tone Curve against faulty Raw files. I don't understand why the DPReview Raw files are out of whack. I've posted an inquiry over at Serious Compacts, in the hope that someone over there has some insight.

In the meantime, I'm developing an alternate calibration technique that uses the GretagMacbeth ColorChecker in Imaging Resource's "viewfinder accuracy" samples. Besides being much more accurate for Panasonic compacts (and who knows what else?), Imaging Resource usually gets their sample Raw files posted very quickly, whereas DPReview doesn't post them until the full review is posted.