conversion/transform.html

<html><head><title>High-speed Conversion of Floating Point Images to
8-bit</title></head><body bgcolor=black text=#c0c0c0 link=#80c0c0 vlink=#ffc0c0>

<p>Linear floating point calculations can also help with
transformations:

<p>The left image is a 1-pixel grid. The middle image is the grid
rotated and scaled down slightly in linear space and converted to sRGB
(the transformation is a 2-pass variation of the Catmull Rom
algorithim with Mitchell filtering). The right image is the same grid
rotated and scaled using image pixels, like most software does.
Notice that it loses a lot of luminance and introduces aliasing
artifacts.

<p><img src=pics/grid.png><img src=pics/gridrotsrgb.png><img src=pics/gridrotlinear.png>

<p>This next compares antialiased graphics drawn in linear space and
then converted to sRGB (left), with the same graphics drawn in sRGB
space (right) like most programs and rendering libraries do.  Simple
antialising is used (the letters are drawn with 16x oversampling and
box-filtered to the result, the shape is drawn using linear pixel
coverage calculations).

<p><img src=pics/textasrgb.png><img src=pics/textalinear.png>

<p>If you examine it closely you will see the antialiasing is much
better on the linear version. However, there are a few <a
href=notlinear.html>problems</a> with linear space for graphics.

<p><a href=composite.html>Go back</a>

</body></html>