[magick-users] How to write an 8-bit PNG even with 16 colours or less {perlmagick]

[Jon Perkin]

Hi Anthony.

Thanks for the suggestion to look at optiPNG. However, having had a look
at it optiPNG is solely for reducing the size of PNGs and can only do
the opposite of what I need: it can reduce the bit depth from 8-bit to
4-bit. I need to increase the bit depth from 4-bit to 8-bit.

Cheers, Jon.


-----Original Message-----
From: Anthony Thyssen [mailto:anthony at griffith.edu.au] 
Sent: 16 January 2008 02:46
To: ImageMagick User List
Cc: Jon Perkin
Subject: Re: [magick-users] How to write an 8-bit PNG even with 16
colours or less {perlmagick]

"Jon Perkin" on  wrote...
| Hi all.
| 
| =20
| 
| I'm using PerlMagick to generate PNG images for use on an embedded
| platform that only supports 8-bit (256-colour palette) PNG images.
| 
| =20
| 
| If one of my images has 16 colours or less, PerlMagick 'cleverly'
| creates a 4-bit (16-colour palette) PNG image, even if I've specified
| depth=3D>8. The 4-bit version does not work on my target platform.
| 
| =20
| 
| Does anyone know if there's any way I can force PerlMagick to give me
an
| 8-bit PNG, even though my image has 16 colours or less? If anyone
knows
| how to do it using one of the other APIs that would still be useful.
| 
| =20
| 
Best idea is to use  "optiPNG"  to set the PNG internal format to
what you specifically need.

  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
 
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