Re: Interlaced vs. Non-interlaced GIFs

Bill O'Donnell x3378 (
Sat, 19 Nov 1994 19:30:18 +0100

From: (David Koblas)
Date: Sat, 19 Nov 1994 09:43:02 -0800 (PST)

> I'm working on a software package that produces HTML documents and
> GIFs (and other files) from a variety of input formats. Currently,
> all GIFs produced by the package are interlaced, so viewers that have
> the capability (e.g. netscape) can get the incremental display that is
> nice to have over slow connections.
> My question is this: is there any downside to always producing
> interlaced images, or should I make it a user preference? For
> example, are there viewers that would choke on interlaced gifs?
> (Mosaic doesn't). Any other issues I should be aware of?

[ useful info deleted- thanks David ]

ps. On this product of yours, are we going to get the option
of specifing what DPI resolution we would like the images
generated for? Since on of the things that I do a lot of
is when I rasterize line drawings is the following process:
Frame -> postscript @ 150 dpi -> scale 50% -> GIF
This results in an nice anti-aliased image.

That's a good question, and I've been wondering what to do about this.
The product (Cyberleaf, it's been announced, so I can finally talk
about it.) uses "Styles" to determine how various components (text,
graphics and tables) should be converted into
HTML/GIF/Postscript. For graphics, these styles include a resolution
parameter (in dpi) for rasterization. Currently, there is no nice GUI
for modifying these styles, but you can add new ones by dropping files
into a directory. A graphic style looks something like this:

(:gif :inline nil nil 75)
:output "<IMG $=SRC $=ALT $?ISMAP>")


What I've been wondering is how important it will be to include a nice
GUI for creating these style descriptions. Basec on your comments, it
seems like I should definitely do it. In any case it'll have to be in
the next release, because I'm getting real close to ship (code freeze
in 11 days, yikes)...

The specification is not very orthogonal, but if covers what people
need to do most of the time. I suppose I'll add and Interlace option
to the style as well.

Thanks again for the help.