Here's a bunch of NTSC graphics that I've rescaled vertically by 116% in
order to look correct on a display with square pixel aspect ratio, which,
apart from most modern displays, the PAL Amiga supposedly features, more
or less at least. I've taken the following steps for the conversion:

1. I've used `ilbmtoppm' from the NetPBM package in Linux to convert the
   IFF ILBM file to PPM (Portable Pixmap), except when converting a HAM
   file. In that case I've used Deluxe Paint V to convert the file to
   24-bit IFF ILBM, due to ilbmtoppm's inaccurate processing of HAM
   files. After that I've used ilbmtoppm on the 24-bit IFF ILBM file.
2. I've rescaled the PPM file with a bicubic filter using the FreeImage
   library and my own little program.
3. I've converted the rescaled PPM file to 24-bit IFF ILBM with
   `ppmtoilbm', also from NetBPM.
4. I've used Deluxe Paint V to convert the 24-bit IFF ILBM file to HAM6
   or HAM8.

I've included both the original and the rescaled 24-bit IFF ILBM files.

There will sometimes be visible artifacts in the HAM pictures, mostly
noticeable in the HAM6 ones, but that is mainly due to limitations of
the HAM mode rather than conversion errors by Deluxe Paint.

Please note that viewing a HAM8 picture will require a machine with the
AGA chipset. That goes for a HAM6 picture with a HiRes (640 horizontal
pixels) `CAMG' viewport modes chunk as well, unless one ignores the
chunk and displays the picture using a LoRes (320 horizontal pixels)
viewport mode combination. As an example, Deluxe Paint V will use a
LoRes screen with overscan when loading such a picture on a machine
without the AGA chipset.

Mats Peterson <matsp888@yahoo.com>
