20D DPI question - DPChallenge Forums

09/13/2006 11:01:46 AM · #2

ALL digital cameras shoot at 72dpi ("normal" monitor resolution). Just change your image size to 300dpi in PS without resampling and you'll get a 11.68 x 7.787" photo.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

09/13/2006 11:06:05 AM · #3

DPI is not a camera-set resolution, it is completely irrelevant to taking pictures. It's a PRINTING resolution. You set it in your editing program to specify the size of the print you'll be making. The "resolution" of your image (the amount of detail it has in it) is determined by its pixel dimensions; in your case, 3504x2336. The DPI figure simply simply indicates to the output device how much those pixels will be spread out when you make the print.

To put it another way, your image contains 8,185,344 pixels (8.2 megabytes, roughly) no matter WHAT "resolution" you choose to convey them at. That's 3504 x 2236 pixels. Printed at 72 DPI you'd have a 48.66 inch print. Printed at 250 DPI you'd have a 14.01 inch print.

Robt.

strangeghost

Canon EOS-7D

09/13/2006 11:07:55 AM · #4

Originally posted by AutumnCat:

The resulting file size/photo size was large - 3504x2336.

The critical piece of info you've got here is that you captured 8 million pixels per shot. DPI is a question asked and answered when you prepare to print. As SCalvart said, 72dpi is the default shown because that's how your computer monitor displays images. You can change the dpi to any figure you want for printing purposes. 150dpi will usually get prints that are "good enough." More like 200 or 250 will improve quality significantly, but you image size (dimension in inches) decreases as you increase resolution. Look over the site tutorials for info on resizing for prints.

too slow for the bear.

Message edited by author 2006-09-13 11:10:24.

AutumnCat

Canon EOS-5D Mark II

Canon EF 24-70mm f/2.8L USM

09/13/2006 11:14:25 AM · #5

Ok - thanks for everyone's replies.
This really helps me understand a bit better.

Not 100% - but will keep trying to learn.

Thanks again!

09/13/2006 11:55:40 AM · #6

Originally posted by AutumnCat:

Ok - thanks for everyone's replies.
This really helps me understand a bit better.

Not 100% - but will keep trying to learn.

Thanks again!

Maybe this will help:

If you take this exact same image and "blow it up" to 3504 inches, it will print at one pixel per inch. If you "shrink it down" to one inch, it will print at 3504 pixels per inch. See? All the information is still there, all 3504 pixels of it on the long dimension; the only thing that's changed is the amount of real estate the information inhabits.

R.

LoveSpuds

Canon EOS-550D Rebel T2i

09/13/2006 11:58:57 AM · #7

Originally posted by Bear_Music:

Originally posted by AutumnCat:
Ok - thanks for everyone's replies.
This really helps me understand a bit better.

Not 100% - but will keep trying to learn.

Thanks again!

Maybe this will help:

If you take this exact same image and "blow it up" to 3504 inches, it will print at one pixel per inch. If you "shrink it down" to one inch, it will print at 3504 pixels per inch. See? All the information is still there, all 3504 pixels of it on the long dimension; the only thing that's changed is the amount of real estate the information inhabits.

R.

I understood what you were talking about till you said this Bear LOL.

09/13/2006 12:11:58 PM · #8

Originally posted by LoveSpuds:

Originally posted by Bear_Music:

Originally posted by AutumnCat:
Ok - thanks for everyone's replies.
This really helps me understand a bit better.

Not 100% - but will keep trying to learn.

Thanks again!

Maybe this will help:

If you take this exact same image and "blow it up" to 3504 inches, it will print at one pixel per inch. If you "shrink it down" to one inch, it will print at 3504 pixels per inch. See? All the information is still there, all 3504 pixels of it on the long dimension; the only thing that's changed is the amount of real estate the information inhabits.

R.

I understood what you were talking about till you said this Bear LOL.

Hmmm.... Let's look at it this way: If you take an image of ten spoons and print it as a 10-inch image, you'll have one spoon per inch of image, right? Each spoon will be an inch wide. Print the same image at 20 inches, and you'll have one spoon every two inches; each spoon will be TWO inches wide. Same spoons, same information, but the spoons get bigger or smaller physically in the print.

Now let's suppose that in the original capture each spoon is composed of 100 individual pixels. So in the 10-inch print, the resolution is 100 pixels per inch. In the twenty-inch print, the resolution is 50 pixels per inch, see?

Same number of pixels in each print, they are just spread out more (further apart from each other) in the larger print.

R.

LoveSpuds

Canon EOS-550D Rebel T2i

09/13/2006 12:15:35 PM · #9

Nope, still not getting it!!!!

(wink wink, anyone wanna bet on how many explanations I can get outta the Bear?)

09/13/2006 12:19:28 PM · #10

Originally posted by LoveSpuds:

Nope, still not getting it!!!!

(wink wink, anyone wanna bet on how many explanations I can get outta the Bear?)

Metaphysical question: "How many pixels can dance on the head of a pin?"

jejejeâ�¢

R.

LoveSpuds

Canon EOS-550D Rebel T2i