Increasing DPI of image

Can Gimp increase the DPI of a PSD file without affecting the physical
dimensions of the image? We have a wedding invitation in PSD that is
72 DPI and the printer needs 300 DPI. Thanks in advance.

Hi,

2008/11/17 Dotan Cohen <dotancohen@gmail.com>:
> Can Gimp increase the DPI of a PSD file without affecting the physical
> dimensions of the image? We have a wedding invitation in PSD that is
> 72 DPI and the printer needs 300 DPI. Thanks in advance.
You need to scale your image up to 300/72 (~416.6%) of it's current
size as well as setting DPI to 300.

To understand why, you need to realize that your original question is
like asking 'How can I make this small while keeping it big?' -- DPI
is literally how many pixels are printed per inch. Less pixels in the
source image == less physical size.

David

2008/11/17 David Gowers <00ai99@gmail.com>:
> Hi,
>
> 2008/11/17 Dotan Cohen <dotancohen@gmail.com>:
>> Can Gimp increase the DPI of a PSD file without affecting the physical
>> dimensions of the image? We have a wedding invitation in PSD that is
>> 72 DPI and the printer needs 300 DPI. Thanks in advance.
> You need to scale your image up to 300/72 (~416.6%) of it's current
> size as well as setting DPI to 300.
>
> To understand why, you need to realize that your original question is
> like asking 'How can I make this small while keeping it big?' -- DPI
> is literally how many pixels are printed per inch. Less pixels in the
> source image == less physical size.
>
> David
>

That is actually what I had done, David, however I figured that it was
worth asking if there is a better way in Gimp. Lots of people smarter
than myself have worked on Gimp, and I should imagine that my
situation is not unique.

Thanks!

Hi,

On Tue, Nov 18, 2008 at 1:24 AM, Dotan Cohen <dotancohen@gmail.com> wrote:
> 2008/11/17 David Gowers <00ai99@gmail.com>:
> That is actually what I had done, David, however I figured that it was
> worth asking if there is a better way in Gimp. Lots of people smarter
Well, you could create a script which only requires you to specify
target DPI, and it would then read the current DPI, calculate the
scaling factor from that vs target DPI, scale the image, and finally
set the DPI.

gimp-image-(set|get)-resolution,
gimp-image-scale (or scale-full) would be the PDB calls you'd need for this.

David

2008/11/18 David Gowers <00ai99@gmail.com>:
> Hi,
>
> On Tue, Nov 18, 2008 at 1:24 AM, Dotan Cohen <dotancohen@gmail.com> wrote:
>> 2008/11/17 David Gowers <00ai99@gmail.com>:
>> That is actually what I had done, David, however I figured that it was
>> worth asking if there is a better way in Gimp. Lots of people smarter
> Well, you could create a script which only requires you to specify
> target DPI, and it would then read the current DPI, calculate the
> scaling factor from that vs target DPI, scale the image, and finally
> set the DPI.
>
> gimp-image-(set|get)-resolution,
> gimp-image-scale (or scale-full) would be the PDB calls you'd need for this.
>

Thanks. I'm only working on one image, but it is good to know for the
future if I run into this again.

Hi,

On Tue, 2008-11-18 at 09:40 +1030, David Gowers wrote:

> Well, you could create a script which only requires you to specify
> target DPI, and it would then read the current DPI, calculate the
> scaling factor from that vs target DPI, scale the image, and finally
> set the DPI.

You could as well go to the Scale dialog, set the desired print
resolution and the desired print size in physical units and click OK.


Sven