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We occasionally hear from users who have decided not to implement Thin Clients because they have heard that they will be limited to only displaying 245 colors. This is simply not true. There are two easy solutions to this problem, both of which we present here. One involves living within a 256 color limit and the other explains how to display anywhere from 12 to 16-bit color on a Thin Client.
The first, and least expensive option is to simply convert the application to use fewer colors. Most of the people that we suggest this to, however, refuse to believe that their screens could possibly be represented in fewer than 32,767 colors. They go on to explain that many of the images they are displaying are very colorful backgrounds for their operator interface screens, some even taken directly from photographs, and when they have tried to show them in less colors they simply look horrible.
There is no doubt that this is true. A digital representation of a photograph, for instance, will use a seemingly endless number of shades of each color to produce the smooth transitions that are present in real life. The image that they start with accurately represents each of these colors with a unique number, matching these numbers up with stored color values in a look up table to determine what percent of red, green and blue each pixel on the computer screen should display. Simply throwing this on a display that will only differentiate 256 different colors results in often random color assignments, and the result is less than pleasing.
If the colors actually used in the high-color image are carefully mapped to colors in a more limited palate, it is possible to represent many of these different colors with the same color with very little effect.
Take for example the following photograph.
This picture is presented here in all of the colors of the original, which for this particular image comes to 114,226 and requires 18 'bits' to display correctly.
We then used a program we purchased off the Internet called Paint Shop Pro, by Jasc Software. This is easily one of the most popular graphics programs available today, and we have found it to be one of the best, especially considering its under $100 price. In addition to the many drawing features, this package has the ability to convert images from almost any graphic format, and allows you to save them in the format of your choice.
The particular feature that we are interested in here though is one they call "Reduce Color Depth". Rather than haphazardly making color assignments, Paint Shop Pro uses sophisticated algorithms to match colors, resulting in a much more natural image.
The image below has had its color depth decreased to 8-bit (256 colors).
As you can see, it is very difficult to tell the two pictures apart.
The second alternative, which avoids any modification of the original images, is to add software to the Windows terminal server to allow it to send more than 8-bit color to the Thin Client.
The standard ICA protocol from Citrix and supplied by ACP with our ThinManager software has set a limit of 256 colors that can be passed to the Thin Client. This is to simplify the communication traveling from the server to the client. If more than this number of colors is required, ACP Thin Clients will also support the higher color provided by Citrix MetaFrame. And since ACP Thin Client technology results in clients that are true terminals (meaning no applications actually run on the client) you can use either the full Citrix MetaFrame product or Citrix MetaFrame for Terminals.
Additionally, if you need the higher colors, make sure that the Thin Client hardware that you have selected will support the display of more than 256 colors - not all of the 40 or so different models of ACP Enabled Thin Clients have the memory required for these images.
For more information on ACP Industrial Thin Client computers, please visit our web site at http://www.thinmanager.com
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