On 2/10/11 00:14, Florian Berger wrote:
I have an issue with unwanted / inferior looking interpolation in scaled Inkscape PNG exports.
(...)
- Shall I file a bug? :)
AFAIU the basic issue is explained well in the comments by Bulia Byak in Bug #166252 "Cannot align boxes properly." https://bugs.launchpad.net/inkscape/+bug/166252 and affects rendering on-canvas as well as exporting to bitmap.
" Imagine that the boundary of two 100% black rectangles falls exactly in the middle of a screen pixel (or export pixel). This means that this pixel is 50% covered by one rect and 50% by the next one. Antialiasing, therefore, paints that pixel 50% transparent black for one rect and 50% transparent black for the other. However if you add two 50% transparencies, you don't get 100% (fully opaque). Instead you get a 75% transparency. You can try that with transparent shapes in Inkscape - that's how transparencies add up. As a result, you get a row of 75% transparent pixels which are clearly visible between two fully opaque rects. That's the artefact you are getting. The exact level of transparency of that row of pixels will depend on where the exact boundary falls within the pixel grid, and therefore will change seemingly randomly as you change zoom or export dpi. Snapping all boundaries to the exact pixel grid, as I explained in the previous comment, is a way to avoid this." bug #166252, comment #5
The problem is tracked in Bug #170356" Suppress antialiasing artefact at the object boundary" https://bugs.launchpad.net/inkscape/+bug/170356 (including several duplicates)
~suv