I have only used the “perspective correction” module two or three times, (and for architectural shots). Most perspective corrections which I have to do are more for aesthetics than accurate depiction, and I tend to use the keystone correction tool in the crop module. I am not certain as to what algorithm is used in the perspective correction module. Perhaps someone close to the developers can answer that. If it did, then one would end up with the correct size ratio of the paper. (Remember to also do lens-correction, as that can also skew your size ratios).
Also, when I said, “phone,” I actually meant camera. My MIL has a home aide who uses her camera phone to “scan” her paperwork every Friday, so while thinking, ‘camera,’ I said, ‘phone.’ One can keep the camera parallel to the paper and still avoid reflections, by not centering the camera to the paper. Still keep it parallel, just not centered. Also, have light-sources off-centered also, (but not opposite to the camera, as angle of incidence equals angle of reflection). are we better doing perspective correction in GIMP or DT? Both programs > have intuitive options for this. Not certain. Never actually tried perspective correction in The Gimp. Again, probably a developer question also. Sincerely, Karim Hosein Top Rock Photography 754.999.1652 On Wed, 16 Sep 2020 at 22:43, Felix E. Klee <felix.k...@inka.de> wrote: > > How about the “perspective correction” module? This should do it > correctly, right? For the given purpose, however, “keystone” in the > “crop and rotate” is way easier to use. So far I have not noticed any > distortion, but my photographs of documents were not angled too crazy. > Normally, I just need a little correction. > > I “scan” with my compact camera, and only if I need to. Sometimes, for > example when taking a photo of a postcard in non perfect lighting > conditions, it’s necessary to shoot at an angle to avoid reflections. ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
