[IanB]

Originally Posted by PhrostByte

if you scan left->right, then l1 is an offset to the left pixel, and r1 is an offset to the right pixel.

it alternates between scanning left->right and right->left (see the calculation of x). I flip the sign on l1/r1 each line too, so r1 is always an offset to the pixel next in line.

it's called "serpentine scanning" and helps avoid some rare bad looking patterns.

Ah, yes I missed this code

   color::dimension_type x = (y & 1) ? (width - xx - 1) : xx;

You have obviously thought about this a lot. So on the Even lines you diffuse error with this kernel

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16 [ 4 5 0 ]

and on the Odd line with this kernel

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16 [ 0 5 4 ]

What other advantages have you found instead of using the default Floyd and Steinberg kernel?

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