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Posted

Don’t know which version handles it correct.

Divide just divides the color values per channel individually.

If you divide a color by itself, you get 1.0 except for zero which is classically undefined, either 0 or 1.

For pure red pixels, the green and blue component is zero, so we get this edge case of 0 / 0.

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

Posted

Wikipedia says 1 as result:

so V1 is ok, V2 is wrong.

Divide

This blend mode simply divides pixel values of one layer with the other, but it's useful for brightening photos if the color is on grey or less. It is also useful for removing a color tint from a photo. If you create a layer that is the color of the tint you wish to remove - such as a pale blue, for scenes that are too cool in color temperature - Divide mode will return that color to white in the resulting composite, as any value divided by itself equals 1.0 (white).

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

Posted

But further testing shows that even V1 will give „wrong“ results when dividing by 0 values.

my testfile has all 2^24 color values, and whenever one color component goes zero you get a non-white result.

dont know why your red example gives a different results in V1, it does not work for other combinations of zero / non-zero RGB channels.

a curves layer inverts the result and boosts lightness to make the issue noticeable 

IMG_2209.png

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

Posted

Thank you very much for your quick response but I still would like to know why Affinity Designer 2 displays the design in a different way.

I did not know about this problem until recently when I opened a design (which I made a long time ago with Affinity Designer 1) with Affinity Designer 2.

 

Posted

Use a document with 2 rectangles, and 2 pixel layers. The upper layer in BM divide

fill all with RGB 255 / 1 / 0

The rectangle show white, but the pixel layer show pink. 
So even in V1 the behavior is inconsistent.

There was an old bug in V1 where vectors layers got colors wrong applied due to wrong color management. This was fixed in V2, and now all layers (pixel and vector) behave identical.

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

Posted

Play with adjusting the color on group level. This will propagate to all layers. See all wrong results when one color channel approaches zero.

BM divide bug V1.afphoto

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

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