Example 3: a copyright image

This page demonstrates how VisibleGif can be used to produce a simple image of a red icon on a transparent background with a copyright notice. The copyright notice added is "© 2000 Copyright WhyWaitForever " which is 32 bytes in length.

Adding a copyright notice makes an image less efficient. If the copyright notice increases the size of the image file by less than 0.1% then the impact on performance is insignificant. A copyright notice is a legal issue. It is for legal advisors to decide whether a copyright notice needs to be added.

The <comment> tag block is a block used to contain comments. It is not used in rendering on image on a display medium. An advantage of using the <comment> tag block is that the copyright notice is immediately visible when the GIF image in this case "exam03.gif" is viewed using a text editor such as MS Notepad.


GIF89a  €     ÿ  !ù    ,       „©Ëí£œ´ÚKƒÞ\·_È¤Çœ›y²$æ !þ
 © 2000 Copyright WhyWaitForever  ;

With more effort the copyright notice could be hidden in the <text> tag block. In this case the foreground, the background and the transparent colour could be set to be the same colour. Most image presentation software ignores the <text> tag block.

There is an even harder to detect method of marking the image with a copyright notice. The colour entries which are not used in the global or local colour table block could be used to hold the bytes of the copyright notice. There are other ways of marking GIF image files but these are quite complex. WhyWaitForever is able to provide consultancy in these specialist areas.

Step 1 - Decide on the image design, shape and characteristics

The first step is to decide on the image width and height. In this case the width is 22 pixels and the height is 17 pixels.
The next step is to decide on shape and colours. Here the image is a simple red shape on a transparent background. The colour black is selected as the transparent colour. Only two colours black and red are needed.

The "<data-rows>" part of the image takes the most time to create. The character ! represents the first colour in the table which is "transparent" black (000000). The character " represents the second character in the table which is red (FF0000). VisibleGif has defined a mapping between particular characters and the index (offset) in the colour table. 17 rows of 22 characters needs to be created.

Finally all the other tags need to be included.

Step 2 - Create the XML tagged file

A text editor program such as MS Notepad can be used to create the XML tagged file. It is usually easier to cut, paste and modify an existing file.

The file contains four tag blocks <header>, <global-color-table>, <graphic> <image> and <comment>. The <comment> tag block is the only difference between this example and that used in example 2. The "<index>" tags are not strictly necessary within the <global-color-table> but are helpful in associating indices with colours. For performance reasons the <comment> tag block is usually placed as the last block. The XML tagged file is as follows:


<?xml version="1.0"?>
<gif>

  <header>
    <signature>GIF</signature>
    <version>89a</version>
    <screen-width>22</screen-width>
    <screen-height>17</screen-height>
    <global-color-present>true</global-color-present>
    <color-resolution>1</color-resolution>
    <colors-sorted-by-importance>false</colors-sorted-by-importance>
    <global-color-size>2</global-color-size>
    <background-color-index>0</background-color-index>
    <pixel-aspect-ratio>0</pixel-aspect-ratio>
  </header>

  <global-color-table>
    <index>0</index>  <red>00</red>  <green>00</green>  <blue>00</blue>
    <index>1</index>  <red>FF</red>  <green>00</green>  <blue>00</blue>
   </global-color-table>

  <graphic>
    <blocksize>4</blocksize>
    <disposal-method>0 No disposal specified</disposal-method>
    <user-input>false</user-input>
    <transparent-color-present>true</transparent-color-present>
    <delay-time>0</delay-time>
    <transparent-color-index>0</transparent-color-index>
  </graphic>

  <image>
    <left>0</left>
    <top>0</top>
    <width>22</width>
    <height>17</height>
    <local-color-present>false</local-color-present>
    <interlaced>false</interlaced>
    <colors-sorted-by-importance>false</colors-sorted-by-importance>
    <local-color-size>0</local-color-size>

    <lzw-minimum-code-size>2</lzw-minimum-code-size>

    <data-rows>
      <row count="0"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="1"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="2"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="3"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="4"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="5"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="6"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="7"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="8"   >!!!!!!!!!!!!!!!!!!!!!!</row>
      <row count="9"   >!!!!!!!!""""""""""""!!</row>
      <row count="10"  >!!!!!!!""""""""""""!!!</row>
      <row count="11"  >!!!!!!""""""""""""!!!!</row>
      <row count="12"  >!!!!!""""""""""""!!!!!</row>
      <row count="13"  >!!!!""""""""""""!!!!!!</row>
      <row count="14"  >!!!""""""""""""!!!!!!!</row>
      <row count="15"  >!!""""""""""""!!!!!!!!</row>
      <row count="16"  >!!!!!!!!!!!!!!!!!!!!!!</row>
    </data-rows>

  </image>
 
 <comment>
  <blocksize>32</blocksize>
  <message>© 2000 Copyright WhyWaitForever </message>
 </comment>

</gif>

This tag file is assumed to be saved as "exam03.xml".

Step 3 - Run VisibleGif to create the GIF image file

A command file needs to be run. This command file reads the XML file called "exam03.xml" and creates the GIF file called "exam03.gif". The command file which is best run in a command window (MS DOS window) is as follows:


rem   exam03.cmd   VG - Example 03 - Create GIF from XML

rem   Set the variables for the program and the run folder
set exelib=h:\vg\bin\vg
set runlib=h:\vg\exam\exam03
set license=########

rem   Change directory to the correct disk drive and run folder
h:
cd %runlib%

rem   Execute vg and send run report to exam03.txt
%exelib% exam03.xml  exam03.gif  %license%  >exam03.txt

After the command file is run successfully the GIF image is created. It can be viewed using web browser software. This provides assurance that the image appears as expected. The run report a copy of which follows should be checked.


I001 Run report for VisibleGif 

     I002 Start time is Wed Mar 01 19:51:52 GMT 2000

     I004 Parameters
          1: exam03.xml
          2: exam03.gif
          3: license: ##################

     I010 File exists and will be read :
          ( exam03.xml )
     I012 File will be created :
          ( exam03.gif )
     I015 Report file is being used :
          ( system )

     I006 Conversion of a XML file to a GIF file 

     I007 List of processed blocks (tags) 
          <header>
               <signature>
               <version>
               <screen-width>
               <screen-height>
               <global-color-present>
               <color-resolution>
               <colors-sorted-by-importance>
               <global-color-size>
               <background-color-index>
               <pixel-aspect-ratio>
          </header>
          <global-color-table>
               <red>     <green>     <blue>
               <red>     <green>     <blue>
          </global-color-table>
          <graphic>
               <blocksize>
               <disposal-method>
               <user-input>
               <transparent-color-present>
               <delay-time>
               <transparent-color-index>
          </graphic>
          <image>
               <left>
               <top>
               <width>
               <height>
               <local-color-present>
               <interlaced>
               <colors-sorted-by-importance>
               <local-color-size>
               <lzw-minimum-code-size>
               <data-rows>
                    <row count="0"   >
                    <row count="1"   >
                    <row count="2"   >
                    <row count="3"   >
                    <row count="4"   >
                    <row count="5"   >
                    <row count="6"   >
                    <row count="7"   >
                    <row count="8"   >
                    <row count="9"   >
                    <row count="10"  >
                    <row count="11"  >
                    <row count="12"  >
                    <row count="13"  >
                    <row count="14"  >
                    <row count="15"  >
                    <row count="16"  >
               </data-rows>
          </image>
          <comment>
               <blocksize>
               <message>
          </comment>

     I000 Processing completed normally 

     I003 End time is Wed Mar 01 19:51:55 GMT 2000

I001 Run report for VisibleGif

Step 4 - Run VisibleGif to double check the created GIF image

It is always a good idea to use the created GIF image as input to VisibleGif to produce a new XML tagged file. The resultant tagged file is listed below. It contains additional information.


<?xml version="1.0"?>
<gif>

 <start-time>Wed Mar 01 19:51:52 GMT 2000</start-time>

 <file>exam02.gif</file>

 <header>
  <signature>GIF</signature>
  <version>89a</version>
  <screen-width>22</screen-width>
  <screen-height>17</screen-height>
   <global-color-present>TRUE</global-color-present>
   <color-resolution>1</color-resolution>
   <colors-sorted-by-importance>FALSE</colors-sorted-by-importance>
   <global-color-size>2</global-color-size>
  <background-color-index>0</background-color-index>
  <pixel-aspect-ratio>0</pixel-aspect-ratio>
 </header>

 <global-color-table>
  <index>0</index> <red>00</red> <green>00</green> <blue>00</blue>
    <edit>!</edit>
  <index>1</index> <red>FF</red> <green>00</green> <blue>00</blue>
    <edit>"</edit>
 </global-color-table>

 <graphic>
  <blocksize>4</blocksize>
  <disposal-method>0 No disposal specified</disposal-method>
  <user-input>FALSE</user-input>
  <transparent-color-present>TRUE</transparent-color-present>
  <delay-time>0</delay-time>
  <transparent-color-index>0</transparent-color-index>
 </graphic>

 <image>
  <left>0</left>
  <top>0</top>
  <width>22</width>
  <height>17</height>
  <local-color-present>FALSE</local-color-present>
  <interlaced>FALSE</interlaced>
  <colors-sorted-by-importance>FALSE</colors-sorted-by-importance>
  <local-color-size>0</local-color-size>

  <lzw-minimum-code-size>2</lzw-minimum-code-size>
  <data-packed>

   <blocksize>29</blocksize>
   <bytes>848FA9CBED0FA39CB4DA4B83DE5CB70E065FC88DA4C79C9B79B224E614</bytes>

   <blocksize>0</blocksize>
   <bytes></bytes>

  </data-packed>

  <data-codes>
   <code size="3" >4</code>    <code size="3" >0</code>
   <code size="3" >6</code>    <code size="3" >7</code>
   <code size="4" >8</code>    <code size="4" >9</code>
   <code size="4" >10</code>   <code size="4" >11</code>
   <code size="4" >12</code>   <code size="4" >13</code>
   <code size="4" >14</code>   <code size="4" >15</code>
   <code size="5" >16</code>   <code size="5" >17</code>
   <code size="5" >18</code>   <code size="5" >19</code>
   <code size="5" >20</code>   <code size="5" >21</code>
   <code size="5" >22</code>   <code size="5" >23</code>
   <code size="5" >20</code>   <code size="5" >1</code>
   <code size="5" >26</code>   <code size="5" >27</code>
   <code size="5" >28</code>   <code size="5" >26</code>
   <code size="5" >13</code>   <code size="5" >29</code>
   <code size="6" >32</code>   <code size="6" >1</code>
   <code size="6" >31</code>   <code size="6" >33</code>
   <code size="6" >28</code>   <code size="6" >35</code>
   <code size="6" >36</code>   <code size="6" >30</code>
   <code size="6" >12</code>   <code size="6" >39</code> 
   <code size="6" >27</code>   <code size="6" >38</code> 
   <code size="6" >39</code>   <code size="6" >44</code>
   <code size="6" >36</code>   <code size="6" >24</code>
   <code size="6" >14</code>   <code size="6" >5</code>
  </data-codes>

<used-colors>
<cin>0</cin> <ced>!</ced> <rgb>000000</rgb> <nin>0</nin> <ned>!</ned>
  <count>290</count>
<cin>1</cin> <ced>"</ced> <rgb>FF0000</rgb> <nin>1</nin> <ned>"</ned>
  <count>84</count>
</used-colors>

<data-rows>
<row count="0"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="1"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="2"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="3"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="4"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="5"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="6"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="7"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="8"   >!!!!!!!!!!!!!!!!!!!!!!</row>
<row count="9"   >!!!!!!!!""""""""""""!!</row>
<row count="10"  >!!!!!!!""""""""""""!!!</row>
<row count="11"  >!!!!!!""""""""""""!!!!</row>
<row count="12"  >!!!!!""""""""""""!!!!!</row>
<row count="13"  >!!!!""""""""""""!!!!!!</row>
<row count="14"  >!!!""""""""""""!!!!!!!</row>
<row count="15"  >!!""""""""""""!!!!!!!!</row>
<row count="16"  >!!!!!!!!!!!!!!!!!!!!!!</row>

</data-rows>

 </image>

 <comment>
  <blocksize>32</blocksize>
  <message>© 2000 Copyright WhyWaitForever </message>
 </comment>


 <end-time>Wed Mar 01 19:51:55 GMT 2000</end-time>

</gif>

The new XML file can be used to produce a new GIF image. This is left as an exercise to the reader.