RawDigger tips and tricks

Started Aug 16, 2015 | Discussions thread
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Iliah Borg Forum Pro • Posts: 21,777
damaged raw data
1

This is not exactly a tip or a trick, but rather an interesting case of raw data damage.

It started like this:

Hi all, Last weekend I took a 360 deg panorama and on processing the files discovered two frames had the partial magenta coloring. Both affected frames appeared identical and were taken 3 seconds apart. I have included the preceding frame as a reference.

The sun would have been at the top of the left hand edge on the affected frame.

The 5D3 has done 35k frames and I was using a 24 105L lens - 2 yrs old and manual exposure. I have not had this problem before and fired off another 73 frames without incident. Fxif intact

Any comments. Thanks Allan

Prior to problem

Problem frame

http://www.dpreview.com/forums/post/56331303

And later Allan was kind enough to published the raw file itself:

https://www.dropbox.com/s/erf18gd24cmqhuc/311A6649.CR2?dl=0

First, looking at the embedded JPEG of the damaged file (opened in FastRawViewer and pressed 'J'), we can see it looks the same wrong, and has a narrow strip of garbage at the very bottom of the shot:

and at 100%, just the bottom:

Based on this, we can deduce a synchronization failure, and it is not memory card or recording interface (or JPEG and raw would look different).

Next, in RawDigger, the histogram of the portion of the frame that should not contain clipping (I selected some of the water):

Clearly, the actual green channels are those R and B in the file, they are similar, as G1 and G2 should be, while G2 is R (lower data numbers, and more contrast in sky, typical), G1 is blue.

What happened here is indeed looks like a synchro problem. One can export the channels and put them in correct order in Phototshop, but a better way is to recompile a decoder in a raw converter with a different Bayer pattern just for this case to rescue the shot.

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