From: pooler@aix02.ecs.rpi.edu (Robert Peter Poole)
Subject: Re: GIF conversion question
Organization: Rensselaer Polytechnic Institute, Troy, NY
Date: Fri, 16 Oct 1992 15:41:02 GMT

In article <1992Oct15.194630.10075@hubcap.clemson.edu> jmauric@eng.clemson.edu writes:
>original file:  sample.gif  256 colors and looks really good on the sun workstation.
>i want to see the file on my amiga.

Simple enough...

>1) should i convert to ham or iff?

HAM is a subset of IFF.  However, a general rule of thumb is, if the GIF is
320x200 or 320x400 (or close), you should convert to HAM or interlaced HAM.
Otherwise, plain IFF or PCHG IFF is your best bet (depending on how many
colors you need, see below).

>2) what program will let me do the conversion?

Well, if you just want to convert GIFs, Wasp is cheap (freeware, I believe, or
maybe shareware...), but it's CLI based and doesn't actually display the image
while converting.  My personal favorite is HamLab Plus.  It's shareware, has
almost all the features of Art Department Professional and costs about an order
of magnitude less.  It outputs to standard IFF, HAM, sliced HAM, dynamic
hires, and PCHG versions of all the standard Amiga video modes.  Why PCHG?
PCHG is a lot like dynamic hires, but it's flexible enough to be used on any
video mode (there's even a 24 bit version of the standard for future hardware).
It eliminates fringing in HAM pictures much the way sliced HAM does.  It
doesn't shut down multitasking the way dynamic hires does.  I have converted
many high resolution 256-color GIF files to PCHG hires interlace, and I have
marvelled at the picture quality.  Probably not as nice as the AGA video modes
like HAM-8, but not bad either.

>3) what are the steps for doing the conversion? 

With Hamlab Plus, clicking on buttons to select what you want the output to
be, display what it'll look like, and convert it.  (Hamlab will let you convert
or display without converting, it's pretty flexible.)  With something like
Wasp, you have to twiddle with command line parameters to get the output
looking "just right," and that involves converting the image each time, then
examining it with a viewer to see if it came out OK.

>4) what if the file was "sample.jpg"? what then? sample questions as above.

Hamlab Plus handles JPEG images extremely well.  Same holds true for TIFF
images, Targa files, etc.  Since Hamlab Plus is designed for 24-bit conversion,
it will take any 24-bit image and (with a little bit of work) will dither and
remap the colors in it until it looks as good as possible on Amiga hardware.

Since JPEG images are 24 bit (not counting the ones that are actually just
converted from GIF images, which there are a lot of on BBSes because of space
constraints), as are many Tiff images, it is to your advantage to use Hamlab
Plus to do the conversion since it will take full advantage of the Amiga's
4096 color palette to represent as closely as possible the 24 bit palette
of the pictures.

If you have an Amiga 4000, you might want to use Art Department Professional
instead since it has AGA support built in, but it also costs well over $100.

>thanks.
>---
>
>                                            --John
>
>============================================================================
>Reply to JMAURIC@ENG.CLEMSON.EDU       |    300 Rippleview Dr.
>Phone: 803-653-3893                    |    Clemson, SC 29631
>============================================================================
>


Disclaimer:  I'm just a satisfied customer of Ed Hanway's.

P.S.  The demo version of Hamlab Plus is available at most ftp sites.  The
only difference between that and the registered version is that the demo
version crops your image to a 512x512 square.

Rob Poole
pooler@rpi.edu
pooler@cs.rpi.edu
Newsgroups: comp.sys.amiga.graphics,comp.sys.amiga.hardware