Resize operation creates grey lines on image with transparency #4588
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I have a basic white colored png with transparency in some areas. 
When using vips_resize() on that image it creates grey lines at the edges where it goes from white to transparent. 
I tried using different kernels but all of them created the same result except for nearest. Due to nearest creating rather poor results on more complex images switching to it in my application isn't really an option though. Is there another way to prevent the grey lines from appearing besides changing the kernel to nearest? |
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image = image.premultiply().resize(0.3).unpremultiply()
There are usually three approaches:
There are other factors to consider too: for example, |
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Your suggestion worked perfectly. Thanks for the help! |
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Hi @most-available-username,
resizedoesn't know about alpha channels -- it treats all bands equally. Therefore, if there's an alpha, you need to premultiply before resize. Something like (python):thumbnailis a higher-level resize operation and it does all of this stuff for you.There are usually three approaches: