Re: permanent page cacheing by WWW browsers

Marc H. (
Wed, 7 Dec 1994 20:55:32 -0800 (PST)

> > I know .gif supports a 'postage
> > stamp' minature embedded within the file, but I'm not aware that .gif
> > also supports multiple resolution versions.
> The phenomena
> you experienced with loading gifs in low res, than progressively higher
> res is accomplished by the GIF "interlace" feature. This allows an image
> to be loaded by every other line, or every second line or fourth line,
> etc...

There's a more likely explanation.

Netscape supports an extension to the <img> tag that looks like this:
<img src="big.gif" lowsrc="small.gif">
When the browser encounters a tag such as this, it loads and displays the
"lowsrc" image, and then gradually replaces the "lowsrc" with the "src"
image. That is the effect you were probably seeing. I've used this for
purposes other than resolution, such as displaying a picture and gradually
replacing it with a labelled version of the same picture.

[In a desperate attempt to avoid losing another mailing list to Netscape

I'm pretty fond of lowsrc as a bandwidth solution in gif display, since
I'm working for a high-end graphics house that doesn't like 16-bit
"trash" littering their pages. Might something of this nature work to
overcome bandwidth problems in vrml? For instance, deliver a "framework"
and then fill it in with textures?

[....well, I did say it was a _desperate_ attempt.]