TestDTAlpha 1.2 (27.1.2008)

Short:        Env-test if pic-dt supports alpha channel
Author:       Andreas R. Kleinert
Uploader:     info ar-kleinert de
Type:         gfx/misc
Version:      1.2 (27.1.2008)
Architecture: m68k-amigaos >= 3.1.0; ppc-morphos >= 1.4.5

TestDTAlpha - Freeware.

This tool is freely redistributable and usable upon the conditions that this
notice remains intact and that modified versions of this archive are not distributed
in any way. The author makes no warranty of any kind with respect to this product
and explicitly disclaims any implied warranties of merchantability or fitness for
any particular purpose.

If you are going to this tool within one of your programs and include
it into your program's distribution, feel free to do so. In this case you have
to add the following statement into your program's documentation:
"This program makes use of TestDTAlpha @ 2008 by Andreas R. Kleinert".

Note: This tool requires dtimage.library - Freeware.
      (included is V3.1 for testing purposes)

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There is at least one V44/45 version of picture.datatype in some OS version
which does NOT support alpha channel export (always returns fixed value
for alpha byte, no matter what is set by the corresponding image Datatype).

This makes it hard for image datatypes to decide whether to support alpha
channel or not.

This tool does the following:

 It checks if the first RGBA pixel of a given image - after loading via
 datatypes - equals 21190385 ($15130355). Actually only the last byte is of
 interest, which contains an alpha value different from $00 or $FF.

 If the check is successful, the following ENV variable is created:

    ENV:Datatypes/PICDTALPHA            ALPHA=OK        [linefeed]

 otherwise

    ENV:Datatypes/PICDTALPHA            ALPHA=BAD       [linefeed]

 The ENV variable must have this entry in the first line.
 Any further content is optional.

Syntax:

    TestDTAlpha 1pixelimage-withalpha.ext

 Three 1 pixel test files for PNG, TIFF and SVG are included.

How to interpret the ENV variable:

 If it does not exist, assume that pic-dt does support alpha channel
 and allow the end-user manual control over any kind of settings.

 If it exists and contains "BAD" then pic-dt does not support alpha channel.
 If it exists and contains "OK" then pic-dt does support alpha channel.

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Main changes since previous versions:

V1.2 (27.1.2007):

 - now using dtimage v3.3, which fixes an issue with PDTA_Remap
   (-> Bernd Roesch)
 - fixed V1.1 history

V1.1 (26.1.2007):

 - now using dtimage v3.2, which always sets PDTA_DitherQuality to 0,
   (-> Thomas Klein)
 - some pic-dts (e.g. with alpha.tif) crashed on 1x1 pixel images on some
   systems (could not reproduce)
   (-> Thomas Klein)
 - added 8x8 pixel image versions

************************************************************************************

© 2008 by Dipl.-Ing. Andreas Kleinert. All rights reserved.