ButtUgly: Main_blogentry_160510

Amiga nostalgia ftw

This Slashdot discussion made me go back to see and nostalgize my pinnacle of Amiga programming - PPT, an Image Processing Program. Taught me everything that I know about multithreaded programming - and I did it without protected memory or any resource tracking :-). Those were the days... Unlike many others, I tried to stick within the RKMs and refused to hit the hardware directly (though an occasional assembly routine here and there never hurt anyone).

One thing I'm fairly proud of still in that code are the RGB -> HAM/HAM8 conversion routines. HAM was this curious Hold-and-Modify mode in which you got to change only one of the RGB components, all the other ones were picked from the left neighbour pixel. Since that meant that in HAM you could only have 16 base colors (4 bit plans) and in HAM8 64, choosing the right palette was really hard. Many people just stuck to a preset palette, and tried to match it, but my routine built a histogram of the image and tried to choose the best possible palette. I still occasionally receive comments about how great the images look - though it's now been a couple of years since the last one - but for a program which hasn't seen active development since ~1995 that's pretty good.

Anyhoo, enough nostalgia. The code is GPL and available in this SVN repo if you want to see how badly I used to program. Lots of C code there... The HAM conversion routines are here and here.