JPEGonDCTV version 1.01, copyright 1994 by Nicolas Dade

What is it?

It's a jpeg viewer that can display both color and greyscale
jpegs using the DCTV display device.


Why this one?

o It's faster than VT or FastJPEG: for a 640x480 jpeg:
    JPEGonDCTV	 1:07 for color, 4plane interlaced (the usual case)
    JPEGonDCTV	 0:31 for greyscale, 3 plane non-interlaced (a quick fullsize)
    JPEGonDCTV	 0:08 for color preview, 3 plane non-interlaced (a small peek)
    FastJPEG1.00 1:35
    VT1.05	 3:10
  (times measured on 7.14Mhz 68010 machine w/ ample fastram)
o It has a preview mode (that doesn't need thumbnail images)
o It handles true greyscale jpegs too.
o It outputs directly to the DCTV display, which is a lot prettier than
  lores interlaced ham6.
o The aspect ratio of the image and the aspect ratio of the display mode
  are obeyed: no more tall faces and oval circles! (Both VT and FastJPEG
  neglect this completely)
o It sanity-checks much more of the jpeg file than VT and FastJPEG do.


What do I need?

o a DCTV display box.
o the dctv.library. This came with your DCTV unless you have an early
  version. If not, or of you want the newest version, it's available on
  aminet.
o Some jpeg images. :)


Details: (also available by entering `JPEGonDCTV ?' in a CLI,
	  and entering a second `?' at the `:' prompt)

the template is:

FILE/A, GREYSCALE=QUICK/S, PREVIEW/S, NOFILTER/S, OVERSCAN/K,
3PLANES/S, NOLACE/S, ASPECT/K, BEHIND/S, SAVEAS, VERBOSE/S:

where

FILE=jpeg picture to display.
GREYSCALE or QUICK=display the image in greyscale (which saves time
	  because the color data doesn't have to be decoded).
PREVIEW=display tiny image.
NOFILTER=do not apply dctv filter to image.
OVERSCAN=the size of the screen in which to display the picture.
	 Choose from [NOM|TXT|GFX|MAX|VID]. The default is TXT.
3PLANES=use 3 bitplanes instead of 4.
NOLACE=use a non-interlaced display instead of an interlaced one
ASPECT=x/y overriding the aspect ratio stored in the jpeg
BEHIND=load the image in a screen behind others, and then pop it
       to front once it's loaded.
SAVEAS= BUGGY, USE WITH CAUTION!
VERBOSE=print comments inbedded in the file to stdout.

so to display the file pic.jpg you could use

 JPEGonDCTV pic.jpg

to display a preview picture of pic.jpg using a non-interlaced,
3-bitplane screen in order to save memory, you would use

 JPEGonDCTV pic.jpg PREVIEW NOLACE 3PLANES

At the moment SAVEAS seems to have a bug in it---use a screen
grabber instead unless you like to see the guru once in a while.


For the moment JPEGonDCTV is CLI only, and one image per
invocation only. Both these restrictions are straitforward to
lift, but I've been caught up with other things so long that this
code has been sitting idle for a whole month now. So I'm dubbing
this version 1.00 and getting it `out there'.


Nicolas Dade / n9rzb / nicolas-dade@uiuc.edu