On Tue, Sep 15, 2009 at 9:40 AM, Patrick Horgan <phorg...@yahoo.com> wrote:
> Jaime Seuma wrote:
> This is an interesting question also to me.
> David Gowers wrote:
> No, if you turn off View->Dot for dot then the DPI relative to your
> display DPI is used to scale your view of the image.
> That much I had already found; but still, when I open a file that has
> been scaled only in resolution (for instance 300->700), still the
> different imageviewers display the same image.
> A 400 pixel wide image will always have exactly 400 pixels across, so on any
> given display device it will show the same irregardless of the resolution.
> On a 70dpi device it will be 5.71 inches wide, on a 90dpi device it will be
> 4.44 inches wide, on a 300dpi device it will be 1 1/3 in.
> If you set the dpi for the image to match the device you intend to show it
> on, then if, for example you change units on the bottom of the drawing
> window to inches, it will accurately report to you the sizes of things as
> you expect to display them.
> It won't make it display any differently though.
In GIMP (and Photoshop, and some other editing software)
it will make it display differently. If your display reports its size
correctly and Dot for Dot is off, the image will display at the
correct size, closely matching the original DPI (of course you do not
get any more actual dots out of this -- it just means that the
relative scale of things is correct).
It's easy to see this if you halve the DPI for one dimension (eg. so
DPI == 36x72) and then turn off Dot for Dot
> On a 300dpi device it will
> still display as 1 1/3 in, even if you set the resolution to 70dpi.
This is true for most simple 'viewing' software, which doesn't scale
the view to be accurate. Not for editors that try to be accurate, such
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