Re: dpi of scans/jpg's: 300 or 72?

Jesse Kercheval wrote:

>dpi is actually Dots per Inch, it's carried over from printers which
>print little dots to create solids and it's standard 'here' whereas
>I guess Metric Countries would use dpc Dots per Centimeter though I've
>never dealt with it.. You want 72 as that's what screen's display and
>that's all you get on the web.. for now.

Well, take care here. There's some other things to consider.

1) Not ALL screens are 72 dpi. Some of the latest high res screens are
closer to 96 dpi I believe. So, it's safest to develop graphics at
more than 72 dpi for better clarity.

2) If you scan at 72 dpi you will end up with a pretty scrappy scan.
Much better to scan at 300 dpi and then downsize your image to
whatever pixel size you want for the web (Photoshop is great for doing
this as it downsizes/rescales much better than any other software I
know). When you subsequently save the graphic into JPEG or GIF format
it will no longer have any dpi information anyway, but if you
originally scanned it at 300+ dpi you'll end up with a sharper image.
Don't believe me? Scan an image at 72 dpi and resize to say 200 pixels
wide. Then scan the same image at 300+ dpi and resize to 200 pixels
wide. I'm sure you'll find the latter is sharper.

3) dpi is really only of relevance to printing. Once you save a
graphic in a web viewable format such as JPEG or GIF the dpi
information is lost. That said, when I develop my web graphics and
interfaces I usually work at 150 or 200 dpi so that if I wanted to put
them into print at some future stage I could. If working on logos I
always work at 300+ dpi because normally the customer will want to be
able to have their logo professionally printed at some stage. I've had
several customers end up using their web logo as their main paper logo
and I've been relieved I worked at 300 dpi and didn't need to rework
it (because you can't just upscale from 72 dpi to 300 dpi for print
without heaps of blur creeping in).

4) It's always better to work in higher dpi and downscale than to work
in lower dpi and then run the risk of needing to upscale. Downscaling
rarely causes loss of quality. Upscaling always will because the
software has to interpolate the missing pixels. Of course, working at
300 dpi on large images will strain your memory and processor
resources so probably isn't worth it. But I feel it is always worth
working at either 150 dpi or 200 dpi as this gives room for manoeuvre.

Regards
Martin Eager
Runic Design
http://www.runic.com

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