17 August 2010

How to enable 8bit or 256 colours for remote applications

Don't get me wrong I love colours lots of them, the more the  better.  But when it comes to RDP, remote app, ICA, VNC, etc you really do not want to use more colours than are necessary.

Let me explain:

8 Bits = 256 colours
15 Bits = 32,768 colours
16 Bits = 65,536 colours
24 bits = 16,777,216 colours

If your remote application is a command line utility like notepad or a command shell you really only need two colours  - black and white.

When you remote application is a graphic application you want more colours - ideally something that is close enough to true colour so that you can't tell that there are "colours missing"

The catch comes when you need to add those colours to your remote data stream.  the more colours you need to render the more data you need to send.  Terminal server used to support 256 Colours or 8 bit colour.  This has slowly disappeared over time and now you actually need to scratch around to find a way to enable this.  Why? You may ask, well few applications today render "nicely" in 8 bit and network performance has increased to the point where this is probably not necessary anymore.  Here in South Africa of course we still have plenty of slow WAN connections so I would still like the option of using 8 bit colour for my very simple text only applications.

So how do we enable 256 colours?

Remote apps are .rdp files that are generated that contain the relevant information for launching that application.  These are plain text file and can be edited in notepad.

In Remote app manager you can add another application.  I am going to use paint.

Now you can "Create .rdp File"  Save this file and then open it with notepad  -- or open notepad and drop the file onto notepad.
You will note that there are many lines of setting and if you look closely they will actually start to make sense.
The one line we are interested in is

session bpp:i:15

That is the line that sets the maximum colour depth.  15 is the default for 15 bit if we change this to 8 for 8 bit it will reduce the number of colour used.

Save the file and launch the application.  From another machine - not through your rdp session.

Your application session is now running in reduced colours.  That's great but how do we get this into our web access?

When publishing a remote app, rdp files are generated and placed in these two locations:


Edit these corresponding files without changing the file names and it will change the file that the client will launch and this will give you the reduced colours you are looking for.

This will however not "work" for all your applications  - case in point - Paint, it just looks terrible.

8 Bit version
15 bit version

!! GOTCHA's !!

Ok so when you are busy testing this stuff you might find that you sometimes get mixed results and sometimes thing don't make any difference.  This is because sessions can be shared to the same host.  So if you have an application open on 15bit the next application will launch on the same session without creating a new reduced colour session.  Make sure you disconnect all session before testing.  Or use your buddy as a lab rat...

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