Broken Images

Roy Tennant rtennant at library.berkeley.edu
Wed Mar 26 16:07:01 EST 1997


Dan's message below made me curious as to any possible benefit of 
delivering an image at a higher dpi than you intend to display. That is, 
for example, delivering a 150 dpi image and scaling it to display as if 
it were a 72 dpi image. To test this, I put up a page at:

http://sunsite.berkeley.edu/Imaging/scaletest.html

using a scan of a russian paper note that I have. You can be your own 
judge, but I convinced myself that I could detect a qualitative 
difference between the others and the one at 150 dpi. Is it enough to 
deliver a 148K image? It may be in some cases, not in others. I viewed it 
on a Apple Multivision 17" monitor using Netscape 3.01. Your mileage may 
vary.
Roy Tennant

On Wed, 26 Mar 1997, Dan Johnston wrote:

> Can you elaborate a little on this scaling problem? While I have 
> experienced various stalls and crashes that I'd like to understand, I 
> didn't realise that Netscape (for example) performs any scaling function, 
> at least for bitmapped images - I thought I always see them 1:1, that is, 
> one screen pixel for one image file pixel, even though I gather the image 
> files for jpeg and gif do contain scaling information.
> 
>  -Dan Johnston
>   djohnsto at library.berkeley.edu
> 
> On Tue, 25 Mar 1997, Shawn J.P. West (BlackSheep) wrote:
> 
> (snip)
> > 
> > 2) The graphic was scaled badly. What i mean is sometimes to save time
> > i've seen web sites where people have scaled a  very large graphic to make
> > it very small this puts more stress on the "client ie. netscape or
> > internet explorer". Because they have to scale the graphic. Even thought
> > netscape uses height and width to draw the web page, microsoft does not
> > and this can slow your page.
> > 
> (snip)
> 



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