[Bug 217908] Re: Pixellated Images in Firefox/Opera due to incorrect EXTEND_PAD implementation in several video drivers

Tom Jaeger ThJaeger at gmail.com
Sun Jul 5 15:41:02 UTC 2009

** Description changed:

  Scaled images in Firefox, Opera, etc. look blurred or pixelated when zoomed.
  This is because firefox is using nearest-neighbor interpolation for upscaling.  It would look better if bilinear filtering were used by Cairo, which requires EXTEND_PAD.  However, EXTEND_PAD is not implemented very well in several video drivers, and Cairo is unable to distinguish drivers that have good implementations from ones with bad ones, so it is currently using a client-side fall back which is deemed too slow by the firefox developers.
  Solving this requires updating each video driver to either implement
  EXTEND_PAD correctly or at least stop advertising it can do it when it
  really can't.  Once this is done, cairo's client-side workaround can be
  removed and firefox can be updated to use EXTEND_PAD.
- The proposed fixes are available (for intrepid and jaunty) in the firefox-smooth-scaling PPA:
+ The proposed fixes are available (for jaunty and karmic) in the firefox-smooth-scaling PPA:
  [Original Report]
  With Ubuntu Hardy beta + latest updates (15th April 2008) I suffer from bad image rendering quality in Firefox.
  To see the type of problem just open the attached screenshot and scale to 100%. 
  The images that are blurred are razor sharp if I do a    right click -> view image  so it is perhaps a problem related to 
  image scaling.
  The problem appears only with my laptop - so perhaps it is not a bug in Firefox but elsewhere (X-windows??/intel-driver??).
  The laptop has a 3-year old Centrino-Platform uses 915 intel driver and has a lcd monitor with 1400x1050 resolution. 
  The rendering problem appears independent of the Desktop-Effects are on/off. So it does not seem to be a problem with
  p.s. Also the text in the Gnome-terminal is somewhat blurred (compared with e.g. text in Gedit)
  p.s. The same homepage renders nicely on my desktop computer with a 1280x1045 and the ati-driver.
  Don't hesitate to ask for more information.

Pixellated Images in Firefox/Opera due to incorrect EXTEND_PAD implementation in several video drivers
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