1/9/2024 0 Comments Rawdigger histograms part 1There are just two spots left on the 2023 Spoonbill Boat 1-1/2 DAY MINI-IPT. Please remember to use my B&H or Bedford’s affiliate programs for all your new gear purchases. Wherever you are and whatever you are doing, I hope that you too have a great day. This blog post took about 90 minutes to prepare (including the time spent on the image optimization) and makes three hundred days in a row with a new, educational post. The photography has been so good that I wish I could stay longer. Last night we enjoyed a wonderful thank you dinner at Shiku Sushi in La Jolla. And a Brandt’s Cormorant nest with two ugly reptilian-looking chicks. In either case, you now have irrefutable proof to show tech support, and they will have to deal with your issue instead of making you try and hang up the phone in frustration.Morning four of the 3rd San Diego was another excellent session with lots of Royal Terns and Brown Pelican in flight, several Black Oystercatchers, and dozens of surfing sea lions. However, in the long run, this camera will be unpredictable and should be replaced or fixed. One can export the channels and put them in the correct order in Photoshop, but a better way would be to recompile a decoder in a raw converter with a different Bayer pattern just for this case to rescue the shot ( if you can't do it yourself, your friendly neighborhood open source raw converter developer should be able to help). If this shot is very important to you, you can try to salvage it. As to the damaged shot (to the right), see above. Histograms of a sampled area on the skyĪs you can see, on the normal shot (the left one) both Green channels are vertically aligned, the Red channel is the weakest, the Blue channel is in-between Green and Red channels. To find out which of the Green channels in raw contains red pixels and which contains blue ones, let's have a look at the per-channel view, keeping in mind that the "true" Red channel typically has lower values for this type of light and subject than "true" Blue, and more contrast and details in the sky are also in the "true" Red channel (Dan Margulis in his books offers a lot of information on recognizing which channel is which).įigure 14. Suppose you do not have a good image to compare to, but (out of curiosity, or for the purpose of repairing the raw file) you still need to attribute channels as they are recorded in raw to the real red and blue (as you've seen, detecting green channels is rather trivial, based on their similarity). It is the channel sequence that is mixed up here the "colors" of pixels and the "colors" of channels do not match. Based on that, it is apparent that the green pixels were recorded in the Red and Blue channels in the RAW file, while the red and blue pixels were recorded in the Green channels. We know that the G and G2 channels are always very similar, while on the skies (except for sunrise / sunset) or the water reflecting the bluish sky, the Red channel is nearly always the weakest and the Blue channel has a peak in-between the Green and Red channel peaks, which is obviously not the case here. So we see that according to the histogram, the Red and Blue channels are nearly equal, while the Green channels (both G and G2) are significantly different. We opened the damaged RAW shot in FastRawViewer, and switching between RAW and embedded JPEG (by pressing "J" on the keyboard), we saw that they both look similar, which proves that we can exonerate the memory card and recording interface from all charges - otherwise the embedded JPEG and RAW would look different.įigure 11. To start solving this mystery, we need to first establish that a faulty memory card did not cause this problem. Later Allan kindly provided three consequent shots, two of which are damaged and one isn't and gave us permission to share them: He wasn't interested in looking at the RAW file. "I contacted Canon (New Zealand) and the tech said 'Clear all camera settings' and see if the problem still occurs. Looks like I will have to contact Canon." 2 There does seem to be a problem with the green channel but with the tools I have I can't get my head around it. "I should have checked all the frames before I left the site!
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