72 dpi pictures with Canon EOS 400D/Digital Rebel XTi

On Sep 21, 6:56 am, shaji <shajiparem... RemoveThis @gmail.com> wrote:
> Thanks a lot cmyk
>
> I was just wondering whether my pictures (with just 72 dpi) would look
> awful if I make a print. My friends Nikon D80 images show a resolution
> of 300 dpi. This really frightened me.
>
> So, you mean to say that I don't need to bother about the default dpi
> value?
>
> Shaji.
>
> On Sep 21, 3:22 pm, "cmyk" <nowh... RemoveThis @ether.net> wrote:
>
> > "shaji" <shajiparem... RemoveThis @gmail.com> wrote in messagenews:1190368976.013835.41930@t8g2000prg.googlegroups.com...
> > > Hi all,
> > > All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
> > > come with horizontal/vertical of just 72 dpi. The image quality I set
> > > is Large-Fine. The width of the pictres is 3888 pixels and hieght is
> > > 2592 pixels.
>
> > > 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
> > > XTi cameras?
>
> > No, the pitcures have no inherent print density. 72dpi is probably just the default chosen by your software in the absence of any
> > metadata in the image file to suggest otherwise.
>
> > > 2. How can I change the resolution (dpi value) of pictures on my
> > > camera?
>
> > You don't. You use your print software to print the picture at whatever size you want and it'll do whatever conversions are
> > required.
>
> > Cheers
> > --
> > cmyk

Hi Shaji,

Your friends images at 300dpi then are probably smaller (in inches)
than your images at 72dpi. They still may have the same number of
overall pixels. In most imaging software you can "resample" the image
to change the dpi value to whatever you want, but it will then change
the "size" in inches of your image.

Regardless, your 10MP shot will print fine at say 8x10 or larger.

Bates...
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

shaji wrote:
> Hi all,
> All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
> come with horizontal/vertical of just 72 dpi. The image quality I set
> is Large-Fine. The width of the pictres is 3888 pixels and hieght is
> 2592 pixels.
>
> 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
> XTi cameras?
> 2. How can I change the resolution (dpi value) of pictures on my
> camera?
>
> Thanks in advance.
> Shaji.
>
What size are the files when you download them onto your computer (int
megabytes)?
Allen
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

"shaji" <shajiparemmal.TakeThisOut@gmail.com> wrote in message news:1190368976.013835.41930@t8g2000prg.googlegroups.com...
> Hi all,
> All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
> come with horizontal/vertical of just 72 dpi. The image quality I set
> is Large-Fine. The width of the pictres is 3888 pixels and hieght is
> 2592 pixels.
>
> 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
> XTi cameras?

No, the pitcures have no inherent print density. 72dpi is probably just the default chosen by your software in the absence of any
metadata in the image file to suggest otherwise.

> 2. How can I change the resolution (dpi value) of pictures on my
> camera?

You don't. You use your print software to print the picture at whatever size you want and it'll do whatever conversions are
required.

Cheers
--
cmyk
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

shaji wrote:
> Hi all,
> All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
> come with horizontal/vertical of just 72 dpi. The image quality I set
> is Large-Fine. The width of the pictres is 3888 pixels and hieght is
> 2592 pixels.
>
> 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
> XTi cameras?
> 2. How can I change the resolution (dpi value) of pictures on my
> camera?

There is no such thing as "dpi" in a digital image file. DPI is "dots
per inch", and there are no "inches" involved in the picture until you
actually print it to a physical medium.

Short answer: don't worry about it, it's only relevant when it comes
time to print.
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

Matt Ion <soundy106.DeleteThis@gmail.com> wrote in news:CDRIi.210659$fJ5.203045
@pd7urf1no:

> shaji wrote:
>> Hi all,
>> All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
>> come with horizontal/vertical of just 72 dpi. The image quality I set
>> is Large-Fine. The width of the pictres is 3888 pixels and hieght is
>> 2592 pixels.
>>
>> 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
>> XTi cameras?
>> 2. How can I change the resolution (dpi value) of pictures on my
>> camera?
>
> There is no such thing as "dpi" in a digital image file. DPI is "dots
> per inch", and there are no "inches" involved in the picture until you
> actually print it to a physical medium.
>
> Short answer: don't worry about it, it's only relevant when it comes
> time to print.

yep, just make sure that in Photoshop, you do not resample the image, just
resize it.
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

Matt Ion <soundy106 RemoveThis @gmail.com> wrote:
>shaji wrote:
>> Hi all,
>> All of the pictures taken with my Canon EOS 400D/Digital Rebel XTi
>> come with horizontal/vertical of just 72 dpi. The image quality I set
>> is Large-Fine. The width of the pictres is 3888 pixels and hieght is
>> 2592 pixels.
>>
>> 1. Is this the default behaviour of all Canon EOS 400D/Digital Rebel
>> XTi cameras?
>> 2. How can I change the resolution (dpi value) of pictures on my
>> camera?

>There is no such thing as "dpi" in a digital image file. DPI is "dots
>per inch", and there are no "inches" involved in the picture until you
>actually print it to a physical medium.

>Short answer: don't worry about it, it's only relevant when it comes
>time to print.

Ok. I agree. But can anyone explain something to me: I would assume
that for an image to be printed, one wants to have as many pixels in
the image as one can get on the printer. Yes, I know that the printer
will adjust to what it is given, but still, I'd like to do it, not the
printer.

Now printers advertize all sorts of resolution. But it is never clear
if that's "real" resolution, interpolated resolution (i.e. the printer
interpolates no matter what it is given), or what.

Further, I can't usually find that information on a manufacturer's web
site.

--
--- Paul J. Gans
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

Paul J Gans <gans.DeleteThis@panix.com> wrote in news:fd0ui7$42o$2@reader1.panix.com:

> Ok. I agree. But can anyone explain something to me: I would assume
> that for an image to be printed, one wants to have as many pixels in
> the image as one can get on the printer. Yes, I know that the printer
> will adjust to what it is given, but still, I'd like to do it, not the
> printer.
>

As long as you're not resampling the image in Photoshop or another photo
editor, the pixel count on your image is equal to the megapixel count of
your photo! ie: take a photo with a Canon Rebel XT (8 MP) and you get an
image that is 3456 pixels by 2304 pixels, for a total of (hit the
calculator) 7,962,624 pixels in your image. Always. (until you change it).
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

On Fri, 21 Sep 2007 03:56:44 -0700, shaji <shajiparemmal.TakeThisOut@gmail.com> wrote:
: Thanks a lot cmyk
:
: I was just wondering whether my pictures (with just 72 dpi) would look
: awful if I make a print. My friends Nikon D80 images show a resolution
: of 300 dpi. This really frightened me.
:
: So, you mean to say that I don't need to bother about the default dpi
: value?

It depends on what the meaning of the word "inch" is. You can regard the
picture as huge but of low resolution or small and of high resolution. Until
you tell the printer how big to make the picture and how many pixels to use to
do it, it doesn't matter.

Bob
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

Good Man <heyho.RemoveThis@letsgo.com> wrote:
>Paul J Gans <gans.RemoveThis@panix.com> wrote in news:fd0ui7$42o$2@reader1.panix.com:

>> Ok. I agree. But can anyone explain something to me: I would assume
>> that for an image to be printed, one wants to have as many pixels in
>> the image as one can get on the printer. Yes, I know that the printer
>> will adjust to what it is given, but still, I'd like to do it, not the
>> printer.
>>

>As long as you're not resampling the image in Photoshop or another photo
>editor, the pixel count on your image is equal to the megapixel count of
>your photo! ie: take a photo with a Canon Rebel XT (8 MP) and you get an
>image that is 3456 pixels by 2304 pixels, for a total of (hit the
>calculator) 7,962,624 pixels in your image. Always. (until you change it).

I understand that. My question was to find out the actual printer
printing density.

For example: if the printer can only handle 300 dpi and I
want to print on 3x5 paper the printer will downsize the
image to 1500x900 pixels from the 3456x2304 in the original
image.

In that case I'd rather do the cropping and downsizing myself
instead of letting the printer do it.

My question is: how do I find out what the *REAL* dpi of the
printer is? I don't necessarily believe the manufacturer's
ads since they sometimes are the result of the printer driver
resizing your image for you.

--
--- Paul J. Gans
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

Paul J Gans wrote:
> Good Man <heyho DeleteThis @letsgo.com> wrote:
<snip>
>>As long as you're not resampling the image in Photoshop or another photo
>>editor, the pixel count on your image is equal to the megapixel count of
>>your photo! ie: take a photo with a Canon Rebel XT (8 MP) and you get an
>>image that is 3456 pixels by 2304 pixels, for a total of (hit the
>>calculator) 7,962,624 pixels in your image. Always. (until you change it).
>
>
> I understand that. My question was to find out the actual printer
> printing density.
>
> For example: if the printer can only handle 300 dpi and I
> want to print on 3x5 paper the printer will downsize the
> image to 1500x900 pixels from the 3456x2304 in the original
> image.

The best way to make an inkjet print that looks as good as a photolab
print is to not go below 200ppi (pixels per inch) and to use your
printer manufacturer's ink and paper.
300ppi is considered the benchmark for "photo quality", but depending on
paper and printer may not make a difference.

This can be checked by dividing the image size in pixels by the output
size in inches, eg: your 3456x2304pixel jpeg/tiff/png/bmp printed at
17.2x11.5 inches would give you a 300ppi printout.
With modern software and inkjet printers, it is best to not resample
(unless you're making your print so large that it will go below 200ppi),
as printing a smaller sized printout increases the ppi and gives the
inkjet printer more information to use when dithering the ink droplets
across the page.

The connection between dpi and ppi is rather circuitous:
dpi as inkjet printer manufacturers state is the combined desinty of ink
nozzles and how finely the printhead carriage can be repositioned (it's
how densly the droplets can be dithered across the page to form smooth
tone transitions), many droplets (the "d" in dpi) are required to render
each image pixel onto paper;
ppi is how densly the image pixels are spread across the paper and if
you go below 200ppi, the image will sart to look pixelated (showing
"jaggies" on sloped and curved edges in the printed picture).
In order to print at 200ppi, your printer must have a stated resoultion
of at least 800dpi (most modern inkjets are 2400x4800dpi), so your
printer if it's only able to go up to 300dpi will produce very coarse
looking results, almost as though you've used the same process as
newspaper printing does (it's particularly bad on gradients of
colour/tone and looks "dotty").
If you have an old inkjet printer which proudly proclaims on the box
something like "Able to print at an amazing 300dpi!", then it's time to
upgrade to a modern inkjet (even the cheapest today don't have dithering
resolution of less than 2400x4800dpi).
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

On 2007-09-22 20:46:43 -0700, dj_nme <dj_nme.TakeThisOut@hotmail.com> said:

> This can be checked by dividing the image size in pixels by the output
> size in inches, eg: your 3456x2304pixel jpeg/tiff/png/bmp printed at
> 17.2x11.5 inches would give you a 300ppi printout.

Actually, this would be 200 pixels per inch.
--
Cease then to grieve for your private afflictions, and address
yourselves instead to the safety of the republic
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

dj_nme <dj_nme.TakeThisOut@hotmail.com> wrote:

>Paul J Gans wrote:

[snip]

>> I understand that. My question was to find out the actual printer
>> printing density.

[snip]

>The connection between dpi and ppi is rather circuitous:
>dpi as inkjet printer manufacturers state is the combined desinty of ink
>nozzles and how finely the printhead carriage can be repositioned (it's
>how densly the droplets can be dithered across the page to form smooth
>tone transitions), many droplets (the "d" in dpi) are required to render
>each image pixel onto paper;

Again, I understand that. The question is: where does one
get the information on that for most printers?

>ppi is how densly the image pixels are spread across the paper and if
>you go below 200ppi, the image will sart to look pixelated (showing
>"jaggies" on sloped and curved edges in the printed picture).
>In order to print at 200ppi, your printer must have a stated resoultion
>of at least 800dpi (most modern inkjets are 2400x4800dpi), so your
>printer if it's only able to go up to 300dpi will produce very coarse
>looking results, almost as though you've used the same process as
>newspaper printing does (it's particularly bad on gradients of
>colour/tone and looks "dotty").

Yes. The question is then given 2400 dpi, how many ppi is that?
I understand this depends on the number of different colors the
printer cartridges hold and on the actual color of the image
pixel -- a blue corresponding to the cartridge blue should only
require one dot while a more complex color might require six,
if the printer has six different colors.

The ultimate goal is to tailor the image to the paper on which
the image is being printed while relying as little as possible
on the algorithms in the printer (other than the color response
curve, of course).

--
--- Paul J. Gans
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi 

sheepdog 2007 wrote:
> On 2007-09-22 20:46:43 -0700, dj_nme <dj_nme.DeleteThis@hotmail.com> said:
>
>> This can be checked by dividing the image size in pixels by the output
>> size in inches, eg: your 3456x2304pixel jpeg/tiff/png/bmp printed at
>> 17.2x11.5 inches would give you a 300ppi printout.
>
>
> Actually, this would be 200 pixels per inch.

You're correct.
Perhaps I shouldn't try posting things that require calculations when
I've got a hangover?
 >> Stay informed about: 72 dpi pictures with Canon EOS 400D/Digital Rebel XTi