Werner? it reach 640x480?? amazing :) , just free some cpu cicles to be able to load some bitmaps in secuence and we have another cool use as really portable presenter... wow Clap clap clap , once sharped is a really cool addon for Ben to produce :)
2011/4/28 David Kuehling <[email protected]>: >>>>>> "Werner" == Werner Almesberger <[email protected]> writes: > >> ubb-vga2 has learned a few new tricks: First of all, it can now >> generate a test image (ubb-vga2 -t), which looks like this: > >> http://downloads.qi-hardware.com/people/werner/ubb/vga/ubb-vga2-tstimg.jpg > > Werner, you're a genious. Zooming into the image, I can't see see any > dithering. How did you manage that many colors? > >> The test image reveals a number of bugs: > >> The diagonal lines should cross exactly at the edge of the display >> area. We can see that a few pixels are missing on the left and at the >> bottom. The top is good but hard to see in this picture. The smears on >> the right are just stale data. > >> This test image also shows that the new board has twice the number of >> colors: a lavish 16 of them ! > >> The horizontal timing jitters by about one pixel time, which makes the >> small text on the color bar difficult to read. There is also a >> distortion at the top, which indicates that the beginning of the frame >> is not exactly synchronized with the rest. > >> The next improvement is better color mapping. I originally used a >> simple threshold-based algorithm that would only consider one channel >> a time and that didn't know of the new luminance channel. > >> The new algorithm assigns a position in the RGB color cube for each >> screen color and then searches for the closest color for every >> pixel. I'll let the result speak for itself: > > You might want to have a look at the color lookup code used in the > allegro game library (alleg.sf.net). They used a 2^5 x 2^5 x 2^5 lookup > table for RGB -> palette color mapping, quickly precumputed by using a > 3-dimensional floodfill algorithm [1]. Allegro gives you a bitmap data > type [2] that allows lowlevel access to bitmap memory, so maybe you could > directly use that. > > Allegro's blit() [3] routine can copy between bitmaps of diffferent color > depth, optionally doing dithering. There's also stretch_blit() for > scaling (albeit without interpolation?). Allegro only supports > 8-bit-per-pixel in paletted modes, but if you just set 256-16 colors to > black, there shouldn't be a problem. All of this is pretty optimized > code. > > Plus you already have code for loading files into bitmaps (bmp, tga or > pcx). > > cheers, > > David > > [1] http://alleg.sourceforge.net/latestdocs/en/alleg021.html#bestfit_color > [2] http://alleg.sourceforge.net/latestdocs/en/alleg001.html#BITMAP > [3] http://alleg.sourceforge.net/latestdocs/en/alleg014.html#blit > -- > GnuPG public key: http://user.cs.tu-berlin.de/~dvdkhlng/dk.gpg > Fingerprint: B17A DC95 D293 657B 4205 D016 7DEF 5323 C174 7D40 > > _______________________________________________ > Qi Hardware Discussion List > Mail to list (members only): [email protected] > Subscribe or Unsubscribe: > http://lists.en.qi-hardware.com/mailman/listinfo/discussion > -- David Reyes Samblas Martinez http://www.tuxbrain.com Open ultraportable & embedded solutions Ben NanoNote, Arduino, Openmoko Hey, watch out!!! There's a linux in your pocket!!! _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
