On Wed, Jan 6, 2016 at 11:40 PM, Émile Cordonnier <emile.cordonnier+darkta...@gmail.com> wrote: > I discovered that there are three "image" sizes in darktable (sizes with > Canon 40D's cr2): > (a) 3944x2622 which is showed in the information panel => it is in fact the > sensor size (and maybe at some point an image size, but I never saw it in > darktable) ;
This is the image size of the files that we handle internally (what the sensor captures) but it includes parts which are not image data. This camera, like many others by Canon includes some black parts of the image that are used for calibrating the black point of the raw data. The reason it's displayed is that it's what is encoded in the file. > (b) 3908x2602 is dt image size (when using the crop module or exporting to > jpg) ; That's the full usable image size after we crop out everything that's not actual image data. > (c) 3888x2592 is the jpg camera size = manufacturer cropped image size. That's a narrower crop that the camera generates from the raw data. Manufacturers usually decide to do that because it's easier to run a demosaic algorithm if you don't have to do special handling for the edges because you have extra image data. > Two points bothers me: > 1. darktable image size is not the image I saw when I took the photo. I > understand that information is "lost" between (a/b) and (c), but (c) is what > I framed. So this additional information is, for me, unwanted in my final > image. That's less than 0.5% in each dimension. If you think you can actually notice it, look up your viewfinder coverage to figure out that what you've framed is actually quite different to what you shot by a much larger margin. Even if you are using live view and thus not a subject to optical viewfinder issues I seriously doubt you can ever notice that 0.5% difference. > 2. with my 40D cr2, I have a 2-pixel-width red+green line on the bottom left > corner on the image... so this additional "information" is even more > unwanted. That's could be a bug then. We may need to crop slightly more to get just the usable data. A new redmine issue with a sample raw file would be useful. I don't see any issue in the sample I just checked. > Last, even if it is not really annoying, I do not understand why is (a) > showed in information panel, since the image size is then (b). Because those are two different bits of information. One is the data the camera wrote into its metadata, the other is the one that is actually true. These formats are weird like that. We could probably make that consistent though. > I found that there were already some discussions about this subject here: > http://sourceforge.net/p/darktable/mailman/message/27637129/ (the motivation > was more about the aspect ratio, but still). > Was the idea of a "vendor cropping plugin" further investigated? rejected? > would it be complicated to implement? There's not much to be gained by it that I can see. If you want a different crop to your images just create a preset with the crop you want and have it auto-apply to images from this camera. For most users getting all the information their sensor gives them is a good default. Cheers, Pedro ------------------------------------------------------------------------------ _______________________________________________ Darktable-users mailing list Darktable-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/darktable-users
