Simons Astro Posted May 2, 2021 Share Posted May 2, 2021 I’m hoping someone can help me with my question. I’m using the latest version 1.9 affinity photo on windows 10, to edit my astrophotography images. The curves histogram is virtually non existent (see photo) It doesn’t matter whether I use the built in stacking feature or use Deep Sky Stacker and bring the image in already stacked, makes no difference, the curves histogram just shows as a tiny little peak at the bottom, although there should be a lot of data there as I’m using a 26mp camera. The levels histogram however is there! Am I doing something wrong, can anyone tell me why it’s not there in curves please! Thanks. Quote Link to comment Share on other sites More sharing options...
firstdefence Posted May 2, 2021 Share Posted May 2, 2021 Welcome to the forum @Simons Astro What layers do you have and which layer do you have selected? Tip: You can use windows Snip to take screenshots or screenshots of selected areas of the screen, which will have a better quality. https://support.microsoft.com/en-us/windows/use-snipping-tool-to-capture-screenshots-00246869-1843-655f-f220-97299b865f6b Quote iMac 27" 2019 Somona 14.3.1, iMac 27" Affinity Designer, Photo & Publisher V1 & V2, Adobe, Inkscape, Vectorstyler, Blender, C4D, Sketchup + more... XP-Pen Artist-22E, - iPad Pro 12.9 (Please refrain from licking the screen while using this forum) Affinity Help - Affinity Desktop Tutorials - Feedback - FAQ - most asked questions Link to comment Share on other sites More sharing options...
Simons Astro Posted May 2, 2021 Author Share Posted May 2, 2021 Hi, thanks for windows snip tip, when I use the Affinity stack feature, after it’s stacked, it takes me to the Astro Photography editing area and its produces a pixel layer, levels layer and a curves layer for you. When I click on the curves layer to make an adjustment, it just shows the small peak on the graph as shown in the photo. Quote Link to comment Share on other sites More sharing options...
kirkt Posted May 3, 2021 Share Posted May 3, 2021 @Simons Astro My guess is that, because most of your image is composed of black background pixels, there is a spike on the left edge of the histogram that is immediately adjacent to the left edge of the histogram frame (so it looks like the frame itself). The large number of these black pixels are dominating the histogram's vertical scale (frequency) so all of the other pixel frequencies have very small appearing peaks relative to the large peak of the black pixels. There is probably also a spike on the white end too, from the clipped stars, etc. Unfortunately, although you can change the range of X values that the curve affects when you make an adjustment, you cannot change the scale ("zoom in") on the histogram. See attached screenshot for a visual interpretation of what I am trying to describe. I just mocked up an astro-like image for reference. Can you post link to download your image file (is it 32 bit per channel?). Kirk Quote Link to comment Share on other sites More sharing options...
Simons Astro Posted May 3, 2021 Author Share Posted May 3, 2021 Hi Kirk Thanks for info, ive not done this before, but i'll try to attach the stacked unedited file that Affinity stacked for me! This has not had any levels or curves adjustments, its stacked with darks, flats and bias frames and is only 1 hr integration, thanks! Regards Simon 587155442_StackedHeartNebulaUneditedA.afphoto Quote Link to comment Share on other sites More sharing options...
Simons Astro Posted May 3, 2021 Author Share Posted May 3, 2021 It is 32bit Quote Link to comment Share on other sites More sharing options...
Simons Astro Posted May 3, 2021 Author Share Posted May 3, 2021 This is the snip image screen shot BTW, thanks! Quote Link to comment Share on other sites More sharing options...
Staff Lee D Posted May 12, 2021 Staff Share Posted May 12, 2021 @Simons Astro This may be because it's in linear colour space and so the tones appear more bunched up. However with a non-linear space, everything is gamma corrected so the tones will occupy more of the histogram space. Quote Link to comment Share on other sites More sharing options...
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