how to round_corner a logo without white background(transparent?) on it using pil?

Question

I got a square logo and I need to round_corner it, searched for a while and got the follow code \"working\":

def round_corner_jpg(image, radius):
    \"\"\"g         


        

Answer 1

Have you tried something like image.putalpha(mask) to replace the image's alpha channel with the mask? This seems like it should do what you want. mask might have to be in 'L' mode for this to work correctly, and image should probaby be 'RGBA', but might be automatically converted for you.

The top answer here provides some good examples: How do I generate circular thumbnails with PIL?

Your mask image looks fine, but I think you want to swap 'white' and 'black', so you have a white rounded rectangle exactly the shape you want your final image to be, on a black background. You will probably also need to use the 'L' mode (greyscale) one.

Once you have this image, you can replace the return ImageChops.add(mask, image) by image.putalpha(mask); return image and this should cause the image to be transparent in only the black areas of the mask.

You might need to convert the image first with image.convert('RGBA') but I think this is unnecessary in later versions of PIL, it does it automatically.

Something like: (sorry can't test this right now)

def round_corner_jpg(image, radius):
    """generate round corner for image"""
    mask = Image.new('L', image.size) # filled with black by default
    draw = aggdraw.Draw(mask)
    brush = aggdraw.Brush('white')
    width, height = mask.size
    #upper-left corner
    draw.pieslice((0,0,radius*2, radius*2), 90, 180, None, brush)
    #upper-right corner
    draw.pieslice((width - radius*2, 0, width, radius*2), 0, 90, None, brush)
    #bottom-left corner
    draw.pieslice((0, height - radius * 2, radius*2, height),180, 270, None, brush)
    #bottom-right corner
    draw.pieslice((width - radius * 2, height - radius * 2, width, height), 270, 360, None, brush)
    #center rectangle
    draw.rectangle((radius, radius, width - radius, height - radius), brush)
    #four edge rectangle
    draw.rectangle((radius, 0, width - radius, radius), brush)
    draw.rectangle((0, radius, radius, height-radius), brush)
    draw.rectangle((radius, height-radius, width-radius, height), brush)
    draw.rectangle((width-radius, radius, width, height-radius), brush)
    draw.flush()
    image = image.convert('RGBA')
    image.putalpha(mask)
    return image