Negadoctor - need help in processing and exporting

Software darktable
,
1

Before getting into serious processing of B/W negatives, I thought I would try out with a quick and dirty capture and processing. Here are the steps I followed:

  1. I created a whitelight on my mobile phone and took a picture using a regular camera.
  2. I broght it into DT, used Negadoctor to convert into a positive
  3. It had a red cast, but as this is a B/W negative, I converted into monochrome.
  4. Thereafter, I did some processing like exposure etc.
  5. It looked fine on the computer screen, as the picture below is seen. This is taken using screen capture.
    image
    image1254Ă—881 264 KB
  6. I tried to export it with my standard parameters
    image
  7. The output is coming completely garbled as this
    LKO_P1010899 -2024.06.17
    LKO_P1010899 -2024.06.171920Ă—1410 1.66 MB

Where am I going wrong, and what should I do to get a proper output? Please help.
I am using DT V4.9 on Windows 11

Below are the raw and xmp file
LKO_P1010899 .RW2.xmp (13.3 KB)
LKO_P1010899 .RW2 (11.2 MB)

This work is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International

This work is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International

2

What happens if you specify only the long edge or don’t scale it… is that output okay???

3

I can reproduce your garbled image with high quality resampling: no. Setting to yes seems to work fine, or turning off allow upscaling.

4

Thanks. Yes, it worked. Any idea why it fails when upscaling is no?

5

I’m obviously missing something here. Which module are you referring to?

6

No. Looks like a case for github bug report.

7

Normally in DT you specify the long edge or the short edge in the scaling of the output box… not both… I was just making a query if you were forcing a scaling that wouldn’t work but it might be something more complex as it turns out…

8

Sorry, but specifying both a long and a short edge should work. At least, I do it all the time, with the same export sizes specified independant of the image size. That’s what allows you to export a series of images of different aspect ratio and size, and still be sure they will fit within the specified rectangle.

That said. I do use high quality resampling, but I do not allow upscaling.

Getting a scrambled image sounds like a bug to me, so should merit a bug report. Before filing a report, check this issue, which seems to provide a fix for 4.8

1 Like
9

That was the bug report I had filed earlier. That is resolved. This is a new issue I am experiencing. As Apostel338 suggested, there is a workaround for it. Will file a new report

10

Yes, this is definitely a bug (and reported). If fails only when using Negadoctor and exporting with Allow Upscaling = yes, High Quality resampling = no. For any other combination, the export goes thru

11

Ya I was on my phone and should have re-read it… I was meaning to say normally you only need to specify one or the other to keep the aspect ratio by default. I was just throwing it out there wondering if you allowed that rather than specifying both for the scaling that something was off but it seems linked to other things that appear to have been rectified…