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                                 D G a m m a

                Screen gamma controller for VIDC 20 machines

                          by David Thomas,  1994-8
                         version 1.10 (06 Jul 1998)
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 Introduction ______________________________________________________________

  DGamma allows you to change the apparent brightness response curve of your
screen display.  It can be used to correct for deficiencies in some monitors,
or even if you just cant seem to get the colours right with those fiddly
dials!

  DGamma works by altering the colour look-up tables inside the video
controller (VIDC) to resemble that of a gamma-curve rather than the usual
diagonal line.  It should be noted that other programs that try to reprogram
the VIDC20 in the same way will not work in conjunction with DGamma.

  DGamma is mode-independent.  It will work in any screen depth and will not
affect the current desktop palette.

  DGamma requires a VIDC20 video controller chip or compatible.  This
currently means any Risc PC, A7000, NC or Phoebe series machine.


 Usage _____________________________________________________________________

  Load DGamma by double-clicking on its icon in a directory display.  It
will load and display its icon to the left of the Display Manager utility. 

  Clicking with SELECT or ADJUST on this icon will open the Gamma control
window.  This is the window you use to alter the gamma-curve.

  At the top of this window is a white box with a black diagonal line in it.
This is a representation of the gamma response curve.
 
  Clicking on either of the up or down arrows to the bottom of the window
will alter the curve.  The up arrow will make the screen brighter, the down
arrow will make the screen darker.


 Command Line Operation ___________________________________________________
 
  DGamma can accept command line parameters to control its behaviour.  They
are :

  -set g    This will automatically set the gamma level. g is the gamma
              level multiplied by 100, so 2.2 would be specified as 220.
  
  -autoquit This will make DGamma immediately quit.  This is useful for
              when you wish to only set the screen gamma up and not have
              the controller loaded.


 Versions __________________________________________________________________

1.02 (26 Jan 1996)
 - This and previous versions were not released.

1.03 (09 Nov 1996)
 - New icon, windows, tidyings, etc. for release.
 - Released under the Acorn User PD Scheme (March 1997).

1.10 (06 Jul 1998)
 - Renamed to DGamma to avoid confusion with Rob Davisons (superior!) Gamma
   application.


 Copyright & Contact Addresses _____________________________________________

  This software is copyrighted work of David Thomas, it is supplied as is;
using it is entirely at your own risk.  I make no warranty as to the fitness
of this software for any purpose.  You are free to distribute this program
toanyone you please, as long as you are not supplying it for personal or
commercial gain and it is delivered with all of the supplied files unaltered.

  If you have any comments, bug reports, suggestions for future versions or
anything else dont hesitate to contact me at -

  Mail:  Mr D.P. Thomas
         20 Rosebery Avenue
         Waterloo
         Liverpool
         L22 2BH

  Email: dpt@tristone.co.uk

  WWW:   http://www.tristone.co.uk/davespace/
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