I have to send an image via the Internet. The person to whom I am sending the image is requesting the photograph be 300 dpi. I am being told by a friend that in order to have a finished image of 300 dpi resolution it must be twice that (600) PPI that matches the physical size of the finished product, which will be 12.5X9 inches.

So . . . he is saying I need to produce the photograph to 600 PPI in order to have a 300 DPI 12.5X9 inch print.

Is this true?

Marilyn

There is some confusion as to the term DPI and PPI. It was general practice to rate monitor resolution as DPI in the past so it became a common language when referring to digital imaging. It should have been PPI all along and has begun a gradual transition to call it what it is ( Dot Per Inch (Printer), Pixels Per Inch, Monitor). If you look at the image resize box in Photoshop 7, It refers to DPI. Photoshop CS now says Pixels.
Some people, out of habit, still call PPI DPI. You need to find out what your friend is saying. I'm sure he means PPI.

Your problem is that if the original image is at 300 ppi at a given size ( WxH), then it will do you no good to upsize it to the same dimensions at higher resolution since the computer is going to be interpolating it (Making up pixels) to get what you want. Nothing they can't do on the other end if that's what they need. At best I would send the native resolution of the original image which is the best you can do. Any upsizing would be left up to the person printing. If you took a 300ppi TIFF image and made it 600ppi, it would end up being about 4 times bigger (30mb would end up equaling 120mb, aprox.)

Professional printing has a much better algorithm for upsizing than anything you or I can afford.
You may also run into problems sending such a large file through the email system unless the other end can accommodate the storage. The average email user mailbox can hold about 5 mb.

Bottom line is if your friend is asking for 300 dpi, I would find out what he really means. Also note that a 300 dpi 12.5x9 in. file is quite large to be sending email, unless youre sending JPG which would be smaller depending on the quality setting. It may get kicked back or not delivered at all.

There are lots of sites on the net that discuss this and a simple search on Google will get you a lot of answers if you want to understand it better. But the bottom line is 300 ppi is about the best you can do without upsizing the print (unless you have one hell of a camera sensor).

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