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                       DOCUMENTATION NOTES
                               FOR
        Informix Image Foundation Datablade Module, Version 2.00
                         DATE: 01/17/2001

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TABLE OF CONTENTS

   I. Overview of Documentation Notes

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I.  Overview of Documentation Notes
===================================

These documentation notes describe features not documented in the 
"Informix Image Foundation DataBlade Module User's Guide."  Informix 
reserves the right to drop support for any of these functions in future 
releases.


SETCOLOR GIF Property
---------------------
The user can force specific colors to appear in a GIF image. GIFs can 
have at most 256 colors so it is sometimes necessary to reduce the number 
of colors in an image when displaying or saving it as a GIF. Specifically, 
this means that most colors in the original image will not appear in the 
resulting GIF. 

When colors are reduced, the server creates a palette for the image by 
finding clusters of similar colors in the image and replacing them with a 
single representative color. The reduced color image is created by 
replacing colors in the original image with the nearest color in the 
palette. The server tries to chose representative colors to minimize the 
difference between the original image and the reduced color image. The 
setcolor property allows specific colors to be inserted into the palette; 
any remaining colors are determined as before.

The format for the setcolor property is exemplified below: 

execute function NewImage(
  CVT('photo.psd', 'wid=200'), 
  'photo.gif?fmt=image/gif,setcolor=0x00RRGGBB'
);

where 0x00RRGGBB represents the color hexadecimal value that determines 
the color you want to be present in the palete.

The setcolor GIF property specifies the color that is to be preserved as a 
6-digit hexadecimal number with two digits for each of the red, green and 
blue components of the color (in that order). 


TRANSPARENCY GIF Property
-------------------------
The following illustrates an example of how the transparency property 
would be used in creating transparent GIF images:

To create a transparent GIF, an index for the transparent color must be 
specified. This index is set using the "transparency" option. In order to 
make a specific color in the original image appear transparent, that color 
should be inserted into the palette using the setcolor option. Setcolor 
also ensures that the transparent color will be at a certain index because 
colors specified using the "setcolor" option are indexed as each "setcolor" 
option is encountered from left to right. The first setcolor is indexed as 
0, the next is indexed as 1 and so on. 

The CVT command for creating a transparent GIF would be as follows: 

execute function NewImage(
  CVT('photo.psd', 'wid=200'), 
  'photo.gif?fmt=image/gif,setcolor=0x00RRGGBB,transparency=0
);

This example assumes that white is the transparent color and inserts it 
into the palette using the property setcolor=ffffff. The inserted color 
is placed at the first palette index, which is 0. The option 
'transparency=0' specifies that palette index 0 is to represent the 
transparent color in the resulting GIF image.