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Image size

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Anonymous
February 20, 2005 3:55:22 PM

Archived from groups: rec.photo.digital (More info?)

Sorry for such an obvious question but being relatively new to digital
photography I am still trying to understand file sizes etc.
I have been asked if I can save and send an image at 420mm x 300mm at
300 dpi.
I'd appreciate any advice on how to save the image at 300 dpi using
Photoshop as i'm not sure wether is the same as pixels per inch at the
moment.

Rob.

More about : image size

Anonymous
February 20, 2005 4:11:11 PM

Archived from groups: rec.photo.digital (More info?)

For that aspect ratio you will have to crop I would imagine.
The cropping tool will allow you to specific the size of the new image
as well as the DPI. Then you just need to save the photo and you should
be all set.

Scott
Anonymous
February 20, 2005 5:04:54 PM

Archived from groups: rec.photo.digital (More info?)

Joseph Meehan wrote:
>
> That is a rather strange request. In any case that would be
>
> 126000 x 90000 or 126K X 90K
>
> Normally someone who knows what they are doing and wants a
specific size
> image file will not specify a size and dpi but rather pixels. An
image file
> does not have dpi or a lineal size. I can print a 126 foot by 90
foot print
> or a .126 mm by .09 mm print from that same file.
>
I am not sure where you are coming up with 126K x 90K, if we are
talking about pixels I get 4960 x 3543.

It is not that odd to specify size and dpi. Many file formats do imbed
the dpi as part of the file. You might want to have a photo scaled like
this if other elements are going to be added to it that are also scaled
at 300 dpi.

Scott
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Anonymous
February 20, 2005 6:19:29 PM

Archived from groups: rec.photo.digital (More info?)

"Eos" <eos9@hotmail.com> wrote in message
news:1108932922.894974.239720@g14g2000cwa.googlegroups.com...
> Sorry for such an obvious question but being relatively new to digital
> photography I am still trying to understand file sizes etc.
> I have been asked if I can save and send an image at 420mm x 300mm at
> 300 dpi.
> I'd appreciate any advice on how to save the image at 300 dpi using
> Photoshop as i'm not sure wether is the same as pixels per inch at the
> moment.
>
> Rob.

My question is, you can do just about anything with Photoshop. So, why do
people, who seem to know all about resolutions, dpi, megapixels, and whatnot
just take your original image and do what they want with it? I hate it when
I'm told that a publisher "must" have the image as a TIFF file. Just take
my JPEG or RAW image and convert it, as I will have to do on my end. Before
I got broadband it was faster to burn images to a CD and drive them where
they had to go instead of e-mailing them.

Sorry 'bout the rant, but I just had to do it. :-)
Anonymous
February 20, 2005 6:59:48 PM

Archived from groups: rec.photo.digital (More info?)

Eos commented courteously ...

[sip]
> I'd appreciate any advice on how to save the image
> at 300 dpi using Photoshop as i'm not sure wether
> is the same as pixels per inch at the moment.

Rob, PPI has *no* meaning whatsoever unless/until you want to
print the image. PPI can easily be changed in PS or PSP
without resampling the image (i.e., making it bigger or
smaller in pixels).

I'd size the image in pixels (sometimes people call this
"resolution" - e.g., 1280 x 960.

If you're trying to resize to a specific size in units such as
inches or mm, that would change as you vary the apparent PPI.

My experience has been that it is best to set the resize units
to "pixels", resize down to what your target audience is, then
save to the appropriate file format.

If using JPEG, that'd also include knowing the approximate
file size limit is, if any, and compressing the image to near
that size, but avoiding overcompression which can damage the
image.

Hope this helps...

--
ATM, aka Jerry
Anonymous
February 20, 2005 8:20:29 PM

Archived from groups: rec.photo.digital (More info?)

Scott W commented courteously ...

> It is not that odd to specify size and dpi.

It is to me, Scott. Could you help me understand your
reasoning by pointing out where inch/mm units and DPI are
used outside of printing? I'm not being a smart aleck, I
don't know and graphics experts that I trust reinforce my
opinion

> Many file formats do imbed the dpi as part of
> the file. You might want to have a photo scaled like
> this if other elements are going to be added to it that
> are also scaled at 300 dpi.

Yes. JPEG is one. PSP 8/9 preserve DPI in JPEG EXIF, but
the number is arbitrary unless you either change it with
or without resampling, or the image came from a scanner
(where DPI is the correct term).

Are you saying here that someone would *want* to create a
specific "as-printed" size for an image in inches/mm and
the DPI that created it?

Excuse my ignorance, but I can't track how this could be
of use to people, since I can change PPI to whatever I
want in PSP 8/9 without changing the image in any way
(except for EXIF, of course).

--
ATM, aka Jerry
Anonymous
February 20, 2005 8:26:22 PM

Archived from groups: rec.photo.digital (More info?)

Sheldon commented courteously ...

[snip]
> I hate it when I'm told that a publisher "must" have
> the image as a TIFF file. Just take my JPEG or RAW
> image and convert it,
[snip]

I fully agree with you, Sheldon on TIFF vs JPEG. But,
publishers can set arbitrary rules, which may well be
decades old, just because they can. And, if you don't do
it their way, you don't get published.

And, while I'm on a rant (for the whole 9 yards, including
pixels, resolution, DPI/PPI, et al), I've also never
understood why a so-called custom printing lab would
steadfastly refuse to accept JPEG and insist on TIFF.

RAW is another story, though, because publishers and print
shops don't to clutter up with IT system with lots of
graphics apps and RAW converters, nor try to keep up with
the rapidly expanding RAW market today.

Again, they get away with it, too, because they can.

End of rant, I now return you to the regularly scheduled
broadcast...

--
ATM, aka Jerry
Anonymous
February 21, 2005 12:39:33 AM

Archived from groups: rec.photo.digital (More info?)

Eos wrote:
> Sorry for such an obvious question but being relatively new to digital
> photography I am still trying to understand file sizes etc.
> I have been asked if I can save and send an image at 420mm x 300mm at
> 300 dpi.

That is a rather strange request. In any case that would be

126000 x 90000 or 126K X 90K

Normally someone who knows what they are doing and wants a specific size
image file will not specify a size and dpi but rather pixels. An image file
does not have dpi or a lineal size. I can print a 126 foot by 90 foot print
or a .126 mm by .09 mm print from that same file.

> I'd appreciate any advice on how to save the image at 300 dpi using
> Photoshop as i'm not sure wether is the same as pixels per inch at the
> moment.
>
> Rob.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math
Anonymous
February 21, 2005 2:00:35 AM

Archived from groups: rec.photo.digital (More info?)

Scott W wrote:
> Joseph Meehan wrote:
>>
>> That is a rather strange request. In any case that would be
>>
>> 126000 x 90000 or 126K X 90K
>>
>> Normally someone who knows what they are doing and wants a
>> specific size image file will not specify a size and dpi but rather
>> pixels. An image file does not have dpi or a lineal size. I can
>> print a 126 foot by 90 foot print or a .126 mm by .09 mm print from
>> that same file.
>>
> I am not sure where you are coming up with 126K x 90K, if we are
> talking about pixels I get 4960 x 3543.
>
> It is not that odd to specify size and dpi.

It has been odd in my experience. Not unknown but a bit odd. There are
a few places that seem to like to use it. While I am sure some feel
otherwise, but I see little use in including print size in the file,
although I know it can be done, at least in some file formats.

And yes, you are right, I did miscalculate, your calculations are likely
correct, mine I know are wrong. Thanks for correcting that. Maybe that is
why I don't like including the size. :-)

> Many file formats do
> imbed the dpi as part of the file. You might want to have a photo
> scaled like this if other elements are going to be added to it that
> are also scaled at 300 dpi.
>
> Scott

--
Joseph Meehan

26 + 6 = 1 It's Irish Math
Anonymous
February 21, 2005 3:02:05 AM

Archived from groups: rec.photo.digital (More info?)

That's 4961 x 3543
Your working in millimeters not inches

"Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
news:p s7Sd.47589$i42.21366@fe1.columbus.rr.com...
> Eos wrote:
>> Sorry for such an obvious question but being relatively new to digital
>> photography I am still trying to understand file sizes etc.
>> I have been asked if I can save and send an image at 420mm x 300mm at
>> 300 dpi.
>
> That is a rather strange request. In any case that would be
>
> 126000 x 90000 or 126K X 90K
>
> Normally someone who knows what they are doing and wants a specific
> size image file will not specify a size and dpi but rather pixels. An
> image file does not have dpi or a lineal size. I can print a 126 foot by
> 90 foot print or a .126 mm by .09 mm print from that same file.
>
>> I'd appreciate any advice on how to save the image at 300 dpi using
>> Photoshop as i'm not sure wether is the same as pixels per inch at the
>> moment.
>>
>> Rob.
>
> --
> Joseph Meehan
>
> 26 + 6 = 1 It's Irish Math
>
Anonymous
February 21, 2005 3:11:23 AM

Archived from groups: rec.photo.digital (More info?)

Open your image file in Photoshop
I'm not sure which version of Photoshop your using, so this might not be the
same in all versions. I'm using CS
Go to: Edit>preferences>units&Rulers
Set the Units to mm Click OK

Use the Crop tool
Set the dimensions in the width and height boxes, set the resolution to 300
pixels/inch
Crop away and save the file (in new folder and/or new name). Resulting image
size should be about 4961 x 3543 pixels
You can check this: Image>Image Size..................

Hope this is helpful
Helge

"Eos" <eos9@hotmail.com> wrote in message
news:1108932922.894974.239720@g14g2000cwa.googlegroups.com...
> Sorry for such an obvious question but being relatively new to digital
> photography I am still trying to understand file sizes etc.
> I have been asked if I can save and send an image at 420mm x 300mm at
> 300 dpi.
> I'd appreciate any advice on how to save the image at 300 dpi using
> Photoshop as i'm not sure wether is the same as pixels per inch at the
> moment.
>
> Rob.
>
Anonymous
February 21, 2005 4:06:03 AM

Archived from groups: rec.photo.digital (More info?)

"Eos" <eos9@hotmail.com> wrote in message
news:1108932922.894974.239720@g14g2000cwa.googlegroups.com...
> Sorry for such an obvious question but being relatively new
> to digital photography I am still trying to understand file
> sizes etc. I have been asked if I can save and send an image
> at 420mm x 300mm at 300 dpi.

420mm = 16.5 inch, and 300mm = 11.8 inch.
So you need to produce an image of 4961x3543 pixels, if printed at 300
ppi.

> I'd appreciate any advice on how to save the image at 300 dpi
> using Photoshop as i'm not sure wether is the same as pixels
> per inch at the moment.

Dpi is a misnomer for all printers that do not use one dot for one
pixel. Photoshop (correctly) calls it Pixels Per Inch (=PPI) in the
Image|Image size dialog. There you first uncheck the "Resample image"
box and enter the 300 PPI (actually doesn't change the file size).
Then you check the "Resample image" box and enter 4961 by 3543 pixels.

Bart
Anonymous
February 21, 2005 11:44:40 AM

Archived from groups: rec.photo.digital (More info?)

Eos wrote:
> Sorry for such an obvious question but being relatively new to digital
> photography I am still trying to understand file sizes etc.
> I have been asked if I can save and send an image at 420mm x 300mm at
> 300 dpi.
> I'd appreciate any advice on how to save the image at 300 dpi using
> Photoshop as i'm not sure wether is the same as pixels per inch at the
> moment.
>
> Rob.
>
I am not sure I completely understand your question. Do you already
have the image in a file? That is, is it already saved in some format,
and you wish to convert it to the size and resolution the party is
asking for.

BTW, he is asking something pretty weird- why does he specify size in
metric units, but pixel pitch in Imperial units?

Anyway, if you already HAVE the image, that is different than if you
need to scan or shoot the image. What he is asking for is quite large-
16.5 x 12. If that is at 300 ppi that is a really large file. Be sure
the image you have already has enough pixels. By my calcs, that is in
excess of 17 megapixels.

If you have to create the image first, do you have a source with that
high a res? It would take a pretty good digicam to create it. However,
if you have a good 8 x 10 (or thereabouts) print from film, you could
scan it at 600 ppi and get what you need.
Anonymous
February 21, 2005 8:40:18 PM

Archived from groups: rec.photo.digital (More info?)

>> It is not that odd to specify size and dpi.
>
> It has been odd in my experience. Not unknown but a bit odd. There
> are a few places that seem to like to use it. While I am sure some feel
> otherwise, but I see little use in including print size in the file,
> although I know it can be done, at least in some file formats.

It has been quite common for me! I prepare files every day that are sent to
designers and printing companies that specify exact size and resolution.
They don't want to have to edit the images any more than necessary, they
just want to drop them into their layout and move on. The original poster
didn't tell us what the intended use for the file was, so we can't conclude
without further investigation whether the given parameters are valid or not.
However, if these parameters were specified by a customer, then they are
valid.

KB
!