[darktable-user] How to compare photos side-by-side
I'm a long-time Lightroom user that has been considering switching to darktable since Adobe switched to subscriptions, and I finally decided it was time to give darktable (2.6.0 on Windows 10) a real test drive on a set of wildlife photos from a morning hike. I've completed my initial round of culling, and my next step is to select the best of the rest so I can process and publish them. In many cases I have a sequence of photos of the same subject, and in LR I would use the compare view to look at pairs of images side-by-side, switching between zoom-to-100% and zoom-to-fit, to find the best of the sequence and give it a rating. I haven't found anything similar to LR's compare view in darktable. Is there some way in darktable that I've missed to compare two photos zoomed to 100%? Thanks. darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
dt-l...@stefan-klinger.de : Matthieu Moy (2019-Jan-24, excerpt): dt runs the image through the whole pipeline, displays the result and uses it for the picker and histogram. A more rigorous approach would run the image through the pipeline up to the output color profile, and then export to monitor space to display the image and to another monitor-independant space for the picker and histogram. That may happen one day, but it's not how it is today indeed. Hmmm, does that mean that the histogram is calculated from the on-screen representation instead of from the image that would be created just before export? I was hoping for the latter, and expected that to be also used to implement gamut checking? That comment ties is with what I am trying to do. Say I find that a given matte paper shows detail between rgb(30,30,30) and (250,250,250) (hypothetical for a b image), I would like to process the image so that its tones fall appropriately between those values. If the global color picker only shows values after conversion to the monitor profile, then those values are not related to the values in the image on export and cannot be used. I cannot know which areas of the image fall below, at or above a precise threshold. Pressing the softproofing icon does not help because although it does show the effect of the printer profile visually, the values reported by the global picker are the same as without softproofing, i.e. they reflect the monitor profile and not the printer profile. I've looked at the histogram with different monitor profile (without checking the box in the global picker that affects the histograms), and it does change, so it seems to work like the global picker. If that is so (I would like a confirmation) then the situation is much worse because even the histogram cannot be trusted when one wants to print. I wonder if someone who knows DT better than I do could perhaps confirm or deny these findings? darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
Matthieu Moy (2019-Jan-24, excerpt): > dt runs > the image through the whole pipeline, displays the result and uses > it for the picker and histogram. A more rigorous approach would run > the image through the pipeline up to the output color profile, and > then export to monitor space to display the image and to another > monitor-independant space for the picker and histogram. That may > happen one day, but it's not how it is today indeed. Hmmm, does that mean that the histogram is calculated from the on-screen representation instead of from the image that would be created just before export? I was hoping for the latter, and expected that to be also used to implement gamut checking? -- http://stefan-klinger.deo/X I prefer receiving plain text messages, not exceeding 32kB. /\/ \ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
> The global color picker works in monitor color space and takes > samples after the complete pixelpipe has been processed. > [...] > I have no idea why this would be considered useful. I don't think anyone claimed that this is useful, but this is easy to implement without breaking the way the pipeline works. dt runs the image through the whole pipeline, displays the result and uses it for the picker and histogram. A more rigorous approach would run the image through the pipeline up to the output color profile, and then export to monitor space to display the image and to another monitor-independant space for the picker and histogram. That may happen one day, but it's not how it is today indeed. -- Matthieu Moy https://matthieu-moy.fr/ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
I don't know, I admit I did not check what Inkscape does by default (I'm not completely clear on color management...). However when I open the png (exported from Inkscape) in Geeqie, which uses my monitor profile (same as the one used in DT), then the rgb values it shows correspond to the white numbers on the centre of patches. Thank you also to the others who responded, I'm going to think this over a bit more and will post tonight. Normand Jim Robinson: I get essentially the same values as you with sRGB as the input color profile, but if I change it to Adobe RGB I get essentially the correct values (sometimes +/- 1). What colorspace was the image saved in? darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
On Wed, 23 Jan 2019 at 18:22, Normand Fortier wrote: > I am creating test images in order to get a better grasp on soft > proofing for printing. These images simply contain patches of different > shades of gray. I created them using Inkscape and then exported to png > (see appended image). > > For example, in the upper left group: > 24 -> (29,29,28) > 25 -> (29,30,29) > 26 -> (30,30,29) > 27 -> (31,31,30) > 28 -> (31,32,31) > 29 -> (32,33,32) > 30 -> (33,34,33) > I get essentially the same values as you with sRGB as the input color profile, but if I change it to Adobe RGB I get essentially the correct values (sometimes +/- 1). What colorspace was the image saved in? Jim darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
Re: [darktable-user] Inaccurate color display or color picker?
Normand Fortier (2019-Jan-23, excerpt): > For example, in the upper left group: > 24 -> (29,29,28) > 25 -> (29,30,29) > 26 -> (30,30,29) > 27 -> (31,31,30) > 28 -> (31,32,31) > 29 -> (32,33,32) > 30 -> (33,34,33) I observe this too, slightly different values though. According to the manual [1] The global color picker works in monitor color space and takes samples after the complete pixelpipe has been processed. so I would assume that you'd see all sorts of effects, including mapping to you monitor's color space. The values reported by darktable are consistent with what is reported when you take a screenshot of darktables showing your image. I have no idea why this would be considered useful. When I re-export your image as PNG, I'd get the original values again, that's quite surprising to me... If no convincing explanation shows up on this thread, file a bug report. [1] https://www.darktable.org/usermanual/en/global_color_picker.html -- http://stefan-klinger.deo/X I prefer receiving plain text messages, not exceeding 32kB. /\/ \ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
