ReGBA by Nebuleon is a Game Boy Advance emulator based ultimately on gpSP 0.9 by Exophase. You can also submit patches on GitHub.

Release notes:

In this release, software bilinear scaling is available, and subpixel-aware scaling is now a special case of software bilinear scaling and is much less rainbow-fringey.

http://boards.dingoonity.org/gcw-releases/regba-gba-emulator-(alpha-1)/165/