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On Thu, Mar 30, 2006 at 09:06:35PM +0100, [EMAIL PROTECTED] wrote:
>
> As usual when I read these sorts of discussions I end up more confused -
> perhaps someone can explain better.
>
> If I generate say a 800 x 800 pixel image in a program, it is just that.
> It has no size in the file. It has no business being assigned a size in
> any image header.
>
> If I display it on my computer screen I can tell to display as 800 x 800
> pixels (say), full size, or scale it by interpolation to any size (in
> pixels) that will fit on my screen. It still has no ruler size in inches
> or any other unit (what is this "inch" anyway?). How big is my 1280 x 854
> pixel screen? Who cares?
>
> If I submit it to a publisher for a paper, they will decide how big to
> print it (usually too small in my experience). All they need is sufficient
> detail that they can degrade it to their preference.
>
> It's only if I send it to a printer that the ruler size becomes relevent,
> and that should be decided (by me) when I print it.
>
> Am I missing something?
>
No, that sounds about right - the problem is that most image headers
do have information about what one pixel should equal in terms of a
real metric (1 pixel = 0.3mm x 0.4mm or whatever), and if that isn't
set in the image header, some software may get confused or assign some
arbitrary value (usually 72 dpi), so in some cases it isn't being
decided by you how big the ruler is. For example, if I take two
identical 1200x1200 PNG images, one with 300dpi in the header and the
other with a blank dpi setting, GIMP will want to print the latter
figure on 17x17" and the 300dpi figure on a 4x4" square.
Now here's the zinger: if you don't define the dpi in the image
header, how does the journal know how big you want the image to
appear? I honestly haven't the foggiest as to how this works at the
journal end.
Hope this clears it up a bit.
Regards,
Tim
--
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Tim Fenn
[EMAIL PROTECTED]
Stanford University, School of Medicine
James H. Clark Center
318 Campus Drive, Room E300
Stanford, CA 94305-5432
Phone: (650) 736-1714
FAX: (650) 736-1961
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