What you describe is not cropping, but rather the setting of an alpha mask.
Here is the simple case for if all your images are the same size as your
template, and only the template has transparancy information:
# Get the Alpha band from the template
tmplt = Image.open('template.png')
A = tmplt.split()[3]
# Get the R, G, B bands from the image to apply the alpha to
im = Image.open('myimage.png')
[R, G, B] = im.split()
# Combine the RGB from the image with the A from the template
newimg = Image.merge('RGBA', (R, G, B, A))
# Write the result back to disk under another name
newimg.save('myimage_rgba.png')
To get from the simple case to more general uses:
- If your images are not all the same size, you need to think about how you
want to scale the template to match.
- If your other images do have some other transparency of their own, combine
the A band from the image with the A band from the template before you merge
everything back together.
Hope this helps, kind regards,
Nils
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I'm trying to take a group of pictures and give them rounded edges. I have a
source image (a rectangle with rounded edges, transparent PNG) and I'd like to
use this as a template. All the target images would become transparent wherever
this source image is transparent.
In other words, I'd be making the same region of the target image transparent
as is transparent in the source image.
Any tips for accomplishing this?
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