             Image Viewer - Quality Images on 16-bit Video Cards

There are so many image viewers available as freeware, you may reasonably ask,
"Why another?".  Well, I could not find a viewer that made the best use of a
64K colour (16-bit) display using algorithms that avoid the image defects
resulting from having a limited number of bits per colour.  These algorithms
are well known in the audio field, and are used to get, for example, 20-bit 
master recordings onto 16-bit CDs.  They work by redistributing the errors 
that result from a reduction of the number of bits into frequency bands that
the ear cannot hear so well.  Similarly, by applying these algorithms to 
images, the errors change from unpleasant banding (low spatial frequency) to
a fine pattern that is much less visible to the eye.  The correlation between
the picture and the error is much less, so the picture appears a lot better.

In simple terms, if you have a 16-bit (65536 colour) video card, this is the 
image viewer program for you.  It will work with 256-colour displays as well,
but the noise introduced will be more perceptible, however even on 256-colour 
cards, JPEG images should still be far better than loading the file into a 
standard Web browser.


Using the Image Viewer:

Simply extract IMG_VIEW.EXE from the archive, install it to a folder of your 
choice, say C:\ImageViewer\, and either execute the program or create a new 
shortcut in your SendTo folder pointing to IMG_VIEW.EXE.  You can then right-
click an image and send it to the viewer.
If you create a shortcut for the image viewer, ensure that the program can be 
passed a single parameter.  This means that in the shortcut's properties, on
the Shortcut tab, the Target entry should look something like this:

  C:\ImageViewer\img_view.exe "%1"

The %1 means pass a parameter on the command line, and the quotes round the 
%1 ensure that if there is a space in the folder or file name that the shell
passes to the viewer, the parameter will be preserved as a whole and not
treated as several parameters.  If you omit the quotes, files with embedded
spaces in the name will not display.

To check the properties of a shortcut, right click the shortcut and choose 
the properties menu from the pop-up list.


Runtime library:

If you don't already have Borland's run-time library, vcl40.bpl you will also 
need to download it.  See:

  http://www.davidtaylor.freeserve.co.uk/software/runtime.html
  http://www.user.globalnet.co.uk/~hermes02/Freeware/VCL40.zip

Extract the file VCL40.BPL from this archive and copy to your Windows System
folder (e.g. \Windows\System or \WinNT\System32).  


Notes:

The program is written with Borland's Delphi 4.01, and most of the source is 
included.  You do not need access to Delphi 4.01 to run Image Viewer.  You 
would need other Delphi units (not included in the archive) in order to re-
compile Image Viewer.


Release information:

V1.0.0   1997 Apr 05  First released version
V1.1.0   1997 May 04  Add 16-bit BMP support in Image_Rd.pas
V1.2.0   1997 May 18  Delphi 3.0
V1.2.2   1997 May 24  Correct interlaced reading code in GIF, overwriting buffer
V1.2.4   1997 Jul 06  Add '.JPE' as valid file extension (for .JPEG)
                      Add About box reading version info from the .EXE file
                      Add grey-scale JPEG input
V1.2.6   1997 Nov 15  Recompile for Borland Delphi 3.01
V1.3.0   1998 Mar 14  Recompile for Borland Delphi 3.01
                      Faster JPEG image loading by using Borland's JPEG unit
                      Make image dither after image loading
                      Get About box, Copyright from the .EXE version information
                      Make properties form Modal (or wrong file info results)
                      Allow escape key to close the form
V1.3.2   1998 Mar 27  Update GIFimage unit to give transparency data
                      GIF unit is now self-registering (for .GIF files)
                      Add version information to form title
                      Don't lower case the file name
V2.0.0   1998 Oct 12  Version for Delphi 4.0
                      Add auto resizing for JPEG images
V2.0.2   1998 Oct 24  Add auto resizing for TBitmaps
                      Correct handling of very small images, incorrectly stretched.
V2.0.4   1998 Nov 20  Better error messages for file not found and bad formats


Contacting the author:

This program is freeware, and remains copyright of David J Taylor, Edinburgh, 
1997-8.  This program is provided "as is", without any support.  Whilst I cannot 
answer queries relating to the use of this program, I'd welcome any comments 
or suggestions for improvements you may have.

This software is based in part on the work of the Independent JPEG Group.
The version information unit came from Brad Stowers.


E-mail:    david.taylor@writeme.com
Web site:  http://www.davidtaylor.freeserve.co.uk/
1998 November 20
