Newsgroups: comp.sys.atari.st
Subject: Photo Chrome - uploaded to a.a
From: shore_c@kosmos.wcc.govt.nz (Craig Shore)
Date: 14 Sep 1992 06:09:24 GMT
Reply-To: shore_c@kosmos.wcc.govt.nz
Organization: Wellington City Council, Wgtn, NZ
NNTP-Posting-Host: kosmos.wcc.govt.nz

Hello,
 I've just uploaded Photo Chrome to a.a, I had a look in atari/graphics
 and couldn't see it there, & assume that it isn't there somewhere else!

The file name is PCHROME.ZOO in the dir atari/new
 on FTP site atari.archive.umich.edu

Here's the first part of the manual to explain a bit about it....

---------------------------------------------------------------------

  ATARI ST/E PHOTOCHROME  v2.01
  -----------------------------

 Concept, Design and Programming

        by Douglas Little.

  (C) 1992 Pixel Twins Shareware Utilities.



You are now the proud owner of the PhotoChrome graphics card
emulator. It is the only one of its type currently available for the Atari
ST and is capable of out-performing all other screen modes including the
infamous HAM and HalfBrite displays on the Commodore Amiga.
It's basic specification is the ability to load most IFF formats,
24-Bit QRT and REAL-3D Raytraced screens (16 million colours) and
VidiChrome digitised 'RGB' colour separations (4096 colours) before
converting to one of six powerful screen modes.

*------------------------------------------------------------------------*

THE 6 CONVERSION MODES
----------------------

The six screen modes are...

1.Spectrum 512> 42/45 cols per scanline from 512 on an ST or STE.
2.Spectrum 4096 > 42/45 cols per scanline from 4096 on an STE.

3.PCS-ST> 48 colours per scanline from 512 on an ST or STE.
4.PCS-STE> 48 colours per scanline from 4096 on an STE.

5.Super HAM> A full 4096 colours out of 4096 on an ST or STE.
6.STE PhotoChrome> 19200 colours out of 32768 on an STE.

Modes 1 and 2 are basically real Spectrum-512 files. They are not
compressed, but Spectrum can do this if you need it. STE mode seems to
handle pictures better than I had expected, since with such a large palette
the colour assignments tend to be used up twice as quickly.

Modes 3 and 4 are my own custom versions of the Spectrum display.
They both have a few extra colours to play with, filling up the streaks
and dots Spectrum can often leave behind. This is my own 'PCS' format
(PhotoChrome Screen) and uses the best of 2 compression methods.

Modes 5 and 6 are actually impossible, so just accept they work
and don't ask too many questions!

SUPER HAM is an emulation of the Hold And Modify mode normally
exclusive to the Commodore Amiga. After some experimentation with my
own Amiga, I found that HAM is not actually as capable of displaying
the more complex colour images (especially with high levels of contrast
or lots of sharp lines) and so renamed my own format 'SUPER HAM'.

PHOTOCHROMEis only available when the source picture contains in
excess of 4096 colours (i.e. QRT 16-million colour pictures), and then
only to STE owners. However, if you do have an STE and some RAW files
knocking about (STF cover disk 35!) then you are in for a treat indeed!
Eat your heart out, VGA! This is the most powerful mode available short
of a real Graphics card, with 19200 colours on-screen at once from a
largish palette of 32768! (15-bit colour). The picture requires two
conversion passes, but is well worth the wait!

N.B. Pictures saved out as Super HAM or PhotoChrome tend to be
anywhere from large to enormous, even with fancy compression. Bear this
in mind when testing out the hatched and fractal stippling options!
(Check out PCSVIEW.DOC for info on better compression...)

*------------------------------------------------------------------------*

* Craig Shore  | Phone (voice)  | Internet:shore_c@kosmos.wcc.govt.nz    *
* 20 Tasman Pl,|  +64 3 3852501 |         :craig@yonder.equinox.gen.nz   *
* Christchurch, New Zealand     | SLNET: 250:700/1266 FIDONET: 3:770/180 *
Newsgroups: comp.sys.atari.st