
   Module name:   JPEG6.MDL 
   Module I.D.:   JPG6 
   Module type:   Import  module
   Author:        Dirk Haun @ WI2
   Status:        Freeware
   Version No:    0.11
   Version date:  01.06.1997
   Purpose:       Importer for JPEG files


Description:

Yes, a JPEG importer already exists for 'Look'n See'.
No, JPEG6.MDL was not meant to replace this originally (hallo John) - 
in the meantime however ...

As I had to deal with JPEGs anyway at the time, a 'Look'n See' module 
was anyway a useful exercise for learning more about the IJG sources.

The differences to the JPEG module by John McLoud:
- Based on the JPEG sources, Version 6a of the IJG (see Credits below)
- Can load progressive JPEGs
- Various options available ('Options/Modules list...' menu entry, select 
  the 'JPEG-6 import' module, click on 'Info', and then on 'Parameters').


Settings:

- DCT
  One can choose between two DCT implementations:
  * Integer (exact)
    Precise and moderately fast integer routines
  * Integer (fast)
    Somewhat faster, but also someone less precise integer routines.

  Note: One normally will not see a difference. And particularly not 
  if dithering takes place subsequently.

- Scale
  The picture size can be reduced during import, with a choice of half, 
  one-quarter or one-eighth of the original size.

- As grey-scale image
  True-Color pictures can be imported directly as grey-scale pictures 
  if desired.
  This option is very useful to provide previews (faster than dithering).

- Stopwatch
  For the curious and others who like to play: The time taken to depack 
  the picture is measured and displayed in the Info window.

Note: The Info window and the 'progress bar window' (which appears 
during importing) always shows the size and colour depth at which the 
picture is being imported (determined by the above settings).
The true values will only be shown if '1:1' was selected for Scale.


Known problems:

- Though CMYK-JPEGs can be loaded, their colours are not quite correct
  (too light). The conversion CMYK->RGB is apparently far from trivial,
  as an extensive(!) search of the literature revealed.

  In fact at present I only know one program that can load CMYK pictures
  in an acceptable quality: PhotoShop. And naturally those guys don't
  reveal how the do it ...

- While importing CMYK-JPEGs the bar that indicated the progress of the 
  importation will run twice. For the second run the text above it should
  actually read 'CMYK -> RGB', but 'Look'n See' ignores this request ...


Standard disclaimer:

This module fulfils its objects for me, which does not mean that 
it will do this everywhere. So should one of these modules do
something unexpected, I cannot be held responsible for any sort
of damage caused thereby (whatever it may be) -- you use it at
your own risk.


Contact address:

The author of this module can be reached in the following ways:

 By snail-mail:

   Dirk Haun
   Europastr. 8
   64569 Nauheim

 By e-mail:

   Dirk Haun @ WI2 (MausNet)


Credits

This software is based in part on the work of the Independent JPEG
Group. Or, to be exact: This software is based *mainly* on the work
of the IJG.
