Resizing GIFs for HTML?

Subject: Resizing GIFs for HTML?
From: Tim Altom <taltom -at- IQUEST -dot- NET>
Date: Fri, 6 Mar 1998 13:20:38 -0500

Whoa now, Mike...I hope this was merely a demonstration of a clever
workaround, rather than a recommendation. I see some killer problems with
doing this in any volume. First off, it's impossible to do this for
hundreds of images in an HTML document. Second, it uses VBScript, something
that Netscape isn't really happy with and older browsers can't handle.

Third and most importantly, GIFs aren't really scalable because they're
bitmaps. Increase their size and you'll rapidly lose the image quality.
Screen resolutions aren't ideal at the best of times and bitmaps only
worsen the problem.

I think what Mike Johnson was talking about was plots, which can be
rescaled nicely even in PDF. Do the same in PDF with bitmapped schematics
and you'll get jaggies. There isn't any comparable vector display for HTML
at all, so the workaround isn't really practical unless you can tolerate a
great deal of display degradation. Further, a B-size vector isn't as big
(usually) as a B-size bitmap, which can, in full 24-bit color, easily be
several meg in size.

>>
>> One thing I really like about PDF images is that they are scalable. You =
>> can zoom in and really see the details - even on a laptop. It is a =
>> great way to put B-sized schematics on line. I can't imagine how I'd do =
>> that with HTML or anything else for that matter.
>>
>> Happy Friday from a snowy Salt Lake City!
>>
>> Mike Johnson
>> OEC Medical Systems
>> Michaelj -at- oecmed -dot- com
>>
>Ok, here's how. The following increases the size of the schematic GIF by a
>factor of 1.5 every time it (the image) is clicked. It decreases the size
>by a factor of 1.5 whenever the image is double-clicked.
>
><img id="MyImage" src="Schematic.gif" alt="My Schematic" WIDTH="40"
>HEIGHT="40">
>
><script language=VBScript>
>
> Sub MyImage_onclick()
> MyImage.Width = MyImage.Width * 1.5
> MyImage.Height = MyImage.Height * 1.5
> End Sub
>
> Sub MyImage_dblclick()
> MyImage.Width = MyImage.Width */1.5
> MyImage.Height = MyImage.Height / 1.5
> End Sub
>
></script>
>
>
>Mike
>
>Michael Wing (mailto:mjwing -at- ingr -dot- com)
>Principal Technical Writer
>Intergraph Corporation; Huntsville, Alabama
>http://www.ingr.com/iss/products/mapping/
>
>"Humpty was pushed!"
>
>
>
>
>
Tim Altom
Vice President, Simply Written, Inc.
317.899.5882 (voice) 317.899.5987 (fax)
www.simplywritten.com
Creators of the Clustar Method (TM)
An out-of-the-box methodology for fast task-based documentation
that's easy to port to paper, WinHelp, Acrobat, SGML, and other media.




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