[Image-SIG] ImageDraw.ellipse bug
lists at johnsto.co.uk
Wed Jul 20 21:49:15 CEST 2005
ImageDraw.ellipse appears to have a bug in it from the inaccuracy of the
code that leads to it drawing ellipses 1 pixel bigger than the specified
The bug is that ellipses of even-width end up being a pixel wider. For
example, ellipses draw with bounding boxes of 1x1, 2x2, 3x3, 4x4, 5x5
are actually drawn using these bounding boxes: 1x1, 3x2, 3x3, 5x4, 5x5.
I don't know if this pattern continues for ever, but the inaccuracy has
been causing precision errors in generated images and ruining the
algorithms I've been working on.
Maybe there's a chance that the Bresenham algorithm could be added to
the library for drawing circles?
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