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Rasterising placed images. Bug or not ?


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I have noticed that if you Rasterise an Image layer, the quality is affected by the size of the image when you Rasterise it.

 

i.e. scale the image to 20 percent and rasterise it, resize it and it is a bit naff. Rasterise it at its full size, and it is OK. There is a noticeable difference, although the original resolution stays the same.

 

Is this a bug ?

Windows PCs. Photo and Designer, latest non-beta versions.

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12 minutes ago, MEB said:

That's because if you scale the image it will be resampled when you rasterise it. If you keep it at full size it will not be resampled.

 

Ah, fair enough.

 

I will just have to load images at full size and make sure I rasterize before resizing. 

 

Thank you

Windows PCs. Photo and Designer, latest non-beta versions.

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31 minutes ago, MEB said:

That's because if you scale the image it will be resampled when you rasterise it. If you keep it at full size it will not be resampled.

Which resampling algorithm does rasterize use? Is it always the same one or maybe a different one when scaling to >100% vs. to <100% of the image's original full size?

All 3 1.10.8, & all 3 V2.5.2 Mac apps; 2020 iMac 27"; 3.8GHz i7, Radeon Pro 5700, 32GB RAM; macOS 10.15.7
Affinity Photo 
1.10.8; Affinity Designer 1.108; & all 3 V2 apps for iPad; 6th Generation iPad 32 GB; Apple Pencil; iPadOS 15.7

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From my (admittedly limited!) knowledge of such matters, bilinear seems a poor choice of algorithm for scaling up. Wouldn't Lanczos3, or even just bicubic, generally yield better results?

Alfred spacer.png
Affinity Designer/Photo/Publisher 2 for Windows • Windows 10 Home/Pro
Affinity Designer/Photo/Publisher 2 for iPad • iPadOS 17.5.1 (iPad 7th gen)

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49 minutes ago, MEB said:

@R C-R

When you scale down it's bilinear from the nearest bitmap.

I am a bit slow-witted this morning but I am not sure what you mean by "nearest bitmap." Nearest to what?

 

14 minutes ago, Alfred said:

From my (admittedly limited!) knowledge of such matters, bilinear seems a poor choice of algorithm for scaling up. Wouldn't Lanczos3, or even just bicubic, generally yield better results?

Also from my limited knowledge, this seems to be true. Is there any easy workaround for this?

All 3 1.10.8, & all 3 V2.5.2 Mac apps; 2020 iMac 27"; 3.8GHz i7, Radeon Pro 5700, 32GB RAM; macOS 10.15.7
Affinity Photo 
1.10.8; Affinity Designer 1.108; & all 3 V2 apps for iPad; 6th Generation iPad 32 GB; Apple Pencil; iPadOS 15.7

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