Aliasing and Anti-aliasing Comparison Tool

ss_2013-12-24_20-32-42This is a tool for illustrating the various types of aliasing which can occur in computer graphics, and how many common methods of anti-aliasing interact with them. I wrote it to accompany an article which will be published some time in the future, and which contains a rather detailed treatment of the topics of aliasing and anti-aliasing.

A main point is to also show aliasing (that is, flickering and image instability) in motion, which is insufficiently captured by the common screenshot or (compressed) video comparisons.

There are 6 types of aliasing shown (transparency aliasing, geometry aliasing (2D and 3D), sub-pixel aliasing, texture aliasing and shader aliasing), and many methods of anti-aliasing are available.

ss_2013-12-24_20-44-07The 1-8 keys are mapped to presets which show some common anti-aliasing methods:

  1.  none
  2. 4x MSAA
    multisampling, generally sparse grid
  3. 2×2 OGSSAA
    ordered grid supersampling with 4 samples
  4. 4x SSAA
    turns the 4 multisamples into supersamples, thus 4x SGSSAA on most HW
  5. FXAA
    just post-processing, see sub-pixel effects
  6. SMAA
    as above (note better motion stability)
  7. 1.5×1.5 OGSSAA + SMAA
    similar to what can be achieved via injection in most games, often decently playable
  8. best
    maximum number of SGSSAA samples plus 2×2 OGSSAA. Close to the “ground truth”, that is the perfect representation of the scene on the pixel grid

Let me know if anything breaks. I do know that the PXAA and TPXAA PPAA methods don’t work on AMD, if anyone wants to help fix it (and has the time) contact me and provide some means of synchronous communication (e.g. Steam ID).

Source code release soon.

Download here!

(If you encounter an error about missing some .dll when running the program, get the Microsoft C++ redistributable here)

(Edit 2014-1-14: updated to fix an issue which could occur with some AMD drivers)

PtBi version 5

I just released a new major version of PtBi, with 2 new features.

Dolby Digital 5.1 decoding

PtBi can now decode audio streams transmitted in Dolby Digital 5.1 format. Together with the existing DTS 5.1 decoding, this should now allow for true surround sound from almost any source. I believe that PtBi is the only Blackmagic Intensity capture program with this type of audio support.
This was easier than I expected, at least at first, because the decoding library functions very similarly to the one I used for DTS, but I was stuck for hours without any progress. It turns out that someone thought it would be a good idea to standardize a bitstream format such that it can be either big-endian or little-endian. Ugh.

SMAA integration

In addition to the existing FXAA, PXAA and TPXAA post-processing AA modes PtBi now also supports SMAA1x. SMAA1x has slightly better edge quality and motion stability than FXAA. I’ll look into integrating SMAA with my predication filters at some point in the future.


Also, I plan to release the source code for PtBi soon-ish. I was always reluctant to do this, since some of it is based on code I wrote almost a decade ago which is pretty terrible, but I cleaned it up slightly now. And some parts of it, like how to integrate the AA modes in OpenGL or how to use the various libraries for audio decoding/playback might be useful to someone. Also, it could help people identify and solve problems with AMD cards, which are always very hard for me to test/debug without access to the hardware.