Thu Jun 24, 2010 7:37 am troron wrote:Because I save it as 72dpi!
It's not debatable.
Haha. I see there's a lot of confusion about dpi (which actually should be called ppi when displayed on screen, but that's a different discussion).
Let me tell you this: a .jpg file has no dpi. You can't save it as 72 dpi and expect that people can't use it. Yes, it has a label in it saying xxx dpi but that doesn't do anything. The only thing that's important is the number of pixels your file has. Then when you want to PRINT it, the size of the print and the number of pixels determine the dpi.
Look at this photo.
http://www.pbase.com/lschell/image/49493702
Now look at the EXIF. I saved it as 2 dpi.
Then look at this one.
http://www.pbase.com/lschell/image/49493718
Take a look at the EXIF again. I saved it as 2000 dpi.
Now here comes the surprise: there is no difference between the photos! They have the exact same quality! When you print them at a certain size, they will be exactly the same. Try it for yourself and you will see that this 72 dpi myth is nonsense.
If you upload your photos using the original camera resolution (say 5184 x 3456), people will be able to print it at a large size, whether you save it as 72 dpi or not. Even if you save it at, say, 10 dpi. The number of pixels (and only that) determine the quality of a print at a certain size. To prevent other people stealing your photos, you should make them smaller, downsize them, before uploading. Forget about the dpi. If people have enough pixels, they can make larger prints just by telling Photoshop how big the print needs to be. Photoshop will adapt the dpi value accordingly without affecting the quality of the image.
I had always been under the impression that DPI was set at printing, as said above based upon the total pixel count and the size of the print. I work on the premise that small files == limited data == poor print resolution.