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How to increase dpi??

 
 
LoShue
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      08-31-2003, 10:44 PM
I have a jpg image which has 230 dpi. Can anyone advise how I can increase
the dpi of that image to 300 or more? Thanks.


 
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J Stafford
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      09-01-2003, 03:19 PM
In article <ZYI4b.1528$f7.138556@localhost>, "LoShue" <(E-Mail Removed)> wrote:

> I have a jpg image which has 230 dpi. Can anyone advise how I can increase
> the dpi of that image to 300 or more? Thanks.


Let me be the one to break this in a gentle way. There is no such thing
as DPI. But you mean pixels-per-(inch,cm,mm,whatever) and the answer is a
qualified Yes. Yes, you can add pixels. Just reset the Image Size. BUT you
will not increase 'resolution', per se. You cannot add detail that is not
there in the original.
 
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Eric Gill
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      09-01-2003, 03:37 PM
(E-Mail Removed) (J Stafford) wrote in
news:(E-Mail Removed):

> In article <ZYI4b.1528$f7.138556@localhost>, "LoShue" <(E-Mail Removed)>
> wrote:
>
>> I have a jpg image which has 230 dpi. Can anyone advise how I can
>> increase the dpi of that image to 300 or more? Thanks.

>
> Let me be the one to break this in a gentle way. There is no such
> thing as DPI. But you mean pixels-per-(inch,cm,mm,whatever) and the
> answer is a qualified Yes. Yes, you can add pixels. Just reset the
> Image Size. BUT you will not increase 'resolution', per se. You cannot
> add detail that is not there in the original.


And upsampling tends to damage the image. If you have been told you need a
higher-rez image and you have no way of getting one without upsampling,
just tell them this is the best you've got.
 
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edjh
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      09-01-2003, 04:15 PM
LoShue wrote:

> I have a jpg image which has 230 dpi. Can anyone advise how I can increase
> the dpi of that image to 300 or more? Thanks.
>
>

Your image does not have 230 dpi. That is a fictional number. You can go
to Image>Image Size and increase to 300 dpi with Resampling OFF but you
will still have the same number of pixels. The "physical size" will
appear smaiier.

--
Comic book sketches and artwork:
http://www.sover.net/~hannigan/edjh.html


 
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Peter
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      09-01-2003, 05:57 PM
Surely the Dpi or Ppi reading refers to the picture at the stated size. So
that changing the resolution without resampling results in a smaller image.
I know that when I have a large image and need to resize for a magazine
picture I ask for the size at which it will be published and then resize to
that leaving the resolution to increase to the maximum the new size will
allow. It always works in practice but am I totally wrong?
And of course referring back to an earlier reply. Dpi does exist - once the
image goes to print.
Cheers,
Peter


 
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Johan W. Elzenga
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      09-01-2003, 09:06 PM
Peter <(E-Mail Removed)> wrote:

> Surely the Dpi or Ppi reading refers to the picture at the stated size. So
> that changing the resolution without resampling results in a smaller image.
> I know that when I have a large image and need to resize for a magazine
> picture I ask for the size at which it will be published and then resize to
> that leaving the resolution to increase to the maximum the new size will
> allow. It always works in practice but am I totally wrong?


Yes, you are. You should not allow the resolution to increase above the
resolution the magazine is printed at, because it only means you are
sending a too large file. The printing resolution is normally 300 dpi.
If needed, you SHOULD resample to downsize the image to the requested
size @ 300 dpi.


--
Johan W. Elzenga johan<<at>>johanfoto.nl
Editor / Photographer http://www.johanfoto.nl/
 
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edjh
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      09-01-2003, 09:48 PM
Peter wrote:

> Surely the Dpi or Ppi reading refers to the picture at the stated size. So
> that changing the resolution without resampling results in a smaller image.
> I know that when I have a large image and need to resize for a magazine
> picture I ask for the size at which it will be published and then resize to
> that leaving the resolution to increase to the maximum the new size will
> allow. It always works in practice but am I totally wrong?
> And of course referring back to an earlier reply. Dpi does exist - once the
> image goes to print.
> Cheers,
> Peter
>
>

Once you go to print. But you have to be clear that the picture consists
of a set amount of pixels. Resampling will add or throw out pixels but
can only degrade picture quality. Size expressed in anything other than
the pixel dimensions is a fiction. There are no inches, centimeters,
etc. in the computer.

--
Comic book sketches and artwork:
http://www.sover.net/~hannigan/edjh.html


 
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Adrian McKenna
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      09-02-2003, 05:59 AM
I should have said s-spline - they have a gallery at the webiste also.


"Adrian McKenna" <(E-Mail Removed)> wrote in message
news:bj1bh6$1bsf$(E-Mail Removed)...
> Just for everyone's info - this is a sample of a product called S-PLINE
> (www.s-pline.com) which someone told be about a while back. It's

resampling
> includes the ability to recognise edges so when increasing an image size,
> produces very good and clear results. I have a friend who owns it and

have
> seen the results.
>
> Cheers,
>
> Adrian McKenna
> www.viewfx.com.au
>
>
> "LoShue" <(E-Mail Removed)> wrote in message
> news:ZYI4b.1528$f7.138556@localhost...
> > I have a jpg image which has 230 dpi. Can anyone advise how I can

increase
> > the dpi of that image to 300 or more? Thanks.
> >
> >

>
>
>



 
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Peter
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      09-02-2003, 12:24 PM
Thanks for that. Just to clarify one point. Does resampling down also
degrade the quality?
Peter


 
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Eric Gill
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      09-02-2003, 01:38 PM
"Peter" <(E-Mail Removed)> wrote in news:bj225j$klo$1
@news6.svr.pol.co.uk:

> Thanks for that. Just to clarify one point. Does resampling down also
> degrade the quality?


The technical answer is "yes", as you are throwing out information.
Downsampling also tends to blur the image.

However, if you are downsampling to hit the target resolution of an output
device (and you do it properly), you will not be able to tell the
difference. I do so all the time with the magazines I produce and it makes
for much smaller files, a big time saver in transmitting and outputting the
files.

Further, remember that downsampling is a one way trip. If there is any
possibility you will need to output that image again at a larger size, keep
a copy of the original.
 
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