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ILBMdt_47.6.lha
Description:IFF ILBM picture datatype 47.6
Developer:Henryk Richter
Readme:
Short: IFF ILBM picture datatype 47.6
Author: Henryk Richter
Uploader: henryk richter gmx net (Henryk Richter)
Type: util/dtype
Version: 47.6
Architecture: m68k-amigaos >= 3.0.0
Distribution: NoCD

Introduction

This is yet another datatype for IFF ILBM pictures. My primary
motivatior for this datatype is that I ran into some issues
loading a number of IFF pictures by my favorite datatypes
based viewer and decided to find a solution for these pictures.

This ILBM datatype supports 1-8 bitplanes including EHB and HAM
in V42 (non RTG) mode. In presence of RTG and/or picture.datatype
V43 or later, 24 Bit images are supported as well. In addition,
planar color mapped data and HAM images are loaded into FastRAM
and internally promoted to chunky representation with active RTG
in order to conserve ChipRAM. Some routines are implemented in
Assembler to provide a good loading speed.

This datatype also handles some of the known issues with ILBM
images generated by certain software like Adobe Photoshop.

In addition to regular ILBM images, this datatype also provides
support for dynamic palettes which are generated by tools like
HAMLab or HAM_convert into PCHG or SHAM chunks.


Installation

At most two files need to be copied for installation: the
datatypes descriptor (ILBM) and the datatype class
(ilbm.datatype). You might want move the existing files to
a safekeeping place (e.g. SYS:Storage/Datatypes/). A reboot
is usually required to enable the new datatype.

From CLI:
Copy Classes/Datatypes/ilbm.datatype Sys:Classes/Datatypes/
Copy Devs/Datatypes/ILBM Devs:Datatypes/

From WB:
Drag the ILBM icon from Devs/Datatypes of this distribution
to SYS:Devs/Datatypes and drag Classes/Datatypes/ilbm.datatype
to SYS:Classes/Datatypes.


Troubleshooting

Malformed IFF ILBM files

Some slightly malformed IFF ILBM files are known that they
can be loaded in popular imaging programs but sometimes fail
to be recognised by datatypes. In such cases, stringent checks
in Datatypes.library and IFFParse.library alongside the
requirement to actually rely on these two libraries prevent
the invocation of ilbm.datatype.

This package contains a commandline tool called "fixiff"
which is able to fix some commonly encountered problems with
IFF ILBM files. It takes two arguments. The first argument
is the input file and the second argument is the resulting
copy.

Example: fixiff Workbench:broken_iff.iff ram:fixed_iff.iff

The fixiff tool will correct incorrect IFF FORM header sizes,
convert out-of-spec run-length encoding to valid encoding,
trim extra data and fill up incomplete BODY data with zeros.

The latest fixiff got two additional switches:
NOMASK will omit the mask in the output
ADDGRAB converts a masked picture into a brush.


CPU compatibility

The datatype is an all-in-one binary for any 68k Amiga. Some
68020+ optimizations are enabled at runtime, if applicable.



History
47.6 - dynamic HiRes and dynamic HAM support (PCHG,SHAM) by
promoting such images to 24 bit (V43 picture.datatype)

47.5 - Mask support in 24 Bit mode
- Transparency masks will only be handed to picture.datatype
for brush type IFFs (i.e. some pictures contain a mask plane
that is actually a drawing stencil)

47.4 - Replaced Datatypes descriptor (DEVS:Datatypes/ILBM) by
a different variant that relies on pattern matching
instead of detection code. This fixes issues with
clipboard operations. Datatypes.library 45.4 now likes
the new descriptor, too.

47.3 - first Aminet release

Upload Date:Dec 24 2021
Category:System/Datatypes
Download:ILBMdt_47.6.lha
Size:59 KB
Downloads:27
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