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Short: HiQuality-HAM8 IFF-24bit image viewer
Author: Smack/Infect! (Michael Henke)
Type: gfx/show
$VER: h8ilbm 0.1 (Sat 16-Dec-2000)
#features
-high quality display for AGA machines (18bit-RGB)
(this program is not particularly useful for graphics board owners)
-supports IFF-ILBM 24bit files only
(there is a similar program called 'h8jpg' on Aminet for JPEG images)
-free software (full source code included, of course)
#requirements
-CPU 68020+
-AmigaOS V37+
-AGA chipset
-asyncio.library V39+
-developed on A1200 (68030+882 @ 40MHz, 16MB FastMem, Delfina1200 DSP)
#recommended
-reqtools.library V38+
-some IFF-ILBM 24bit files
#how to use
h8ilbm is a shell-only program, these options can be used:
FILES............one or more filenames (the keyword FILES is optional).
if omitted a reqtools file requester appears.
MID <number>.....screen mode ID.
if omitted the default mode ID 0x8020 is used.
specify a decimal or hexadecimal (prefix $ or 0x) value.
(example: PAL:Super-High Res - 167968 or 0x29020)
SMR..............summon a reqtools screen mode requester.
Use these keys on the h8ilbm screen:
Esc..................quit
Space/Return/RMB.....next image
cursor keys..........scroll image (8 pixels)
shift + cursor keys..scroll image (32 pixels)
alt + cursor keys....scroll image (maximum)
(if the screen is larger than the visible area you can scroll it around
with mouse movements)
#known problems
-images are shown in a low resolution and/or with wrong aspect ratio
This is a side-effect of the particular rendering technique used in this
image viewer. It's sometimes called "18bit-HAM8 RGBB" mode and has often
been used in demos for colourful 3D-Effects and such stuff. The basic
principle is that each original true color pixel (24bit) is represented
by four screen pixels in a special HAM8 pattern. This results in the image
appearing four times wider on the screen, which can be compensated by
displaying the screen in a "Super-HiRes" mode (e.g. PAL: 1280x256 pixels).
The screen then looks like "Low-Res" (320x256) because all those four-
component pixels mix nicely into single "true color" pixels.
-rendered images use very much chip memory
This is another consequence of the rendering technique used: graphics
memory consumption is four times higher than with "normal" image viewers.
h8ilbm tries to load the entire image into chip memory, creating a large
screen that can be moved smoothly and easily using the mouse. However, if
the image is too large then h8ilbm switches to "buffer mode": the image
is loaded to FastRAM and only a part of it is rendered to a normal-sized
screen. Move this part around using the keys listed above.
#author
mailto: Michael Henke <smack@smack.de>
h8ilbm - HiQuality-HAM8 IFF-24bit image viewer
Copyright (C) 2000 Michael Henke
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA