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View Full Version : Making digital prints - how to change image dpi?


Pseudolus
12-14-2002, 12:11 PM
I'm trying to get some of my digital image files into the proper format to be taken to a professional digital photo lab for printing. I'm using Paint Shop Pro, but I think things are done similarly in Photoshop and other programs.

The lab told me that they want JPG files, 300dpi, so an 8x10 image would be 8*300*10*300 = 7.2 Mpixels. I have more than enough pixels in my image, but when I look at the "image information" of my file, there's a "pixels per inch" property that's set at 1200, which I think is the resolution I had my scanner set on when I scanned the original slide. Naturally, I don't want a print the same size as a 35mm slide. (Hard to find a frame that small.) This number being so high makes the listed physical image size teeny tiny (as listed in "image information"), although I can make it appear on my monitor any size I want.

My questions:

1) Is it important for me to change what the ppi setting of the file is, or is having the required # of pixels good enough for the lab to print it the size I want?

2) If answer to 1 is "yes", how do I go about doing it?

3) The help files to PSP recommend a ppi of 80-100ppi for a file to be printed at 300dpi. (Ppi is screen, and dpi is paper, right?) Any idea why this is? Should I have 8*100*10*100 = 0.8 Mpixels in my image for printing? That seems awfully low.

4) Are these the dumbest questions, or what? (feel free to skip this one)

Any help much appreciated!

Obi-Wan Kenobi
12-14-2002, 12:57 PM
1) I would think that more pixels than requested should not be a problem, other than that it will take up more space on the CD.
2) Photoshop Elements will do this. I suspect Graphics Workshop (http://download.com.com/3000-2192-10135052.html?tag=lst-0-1) will as well,
3) That seems low to me, as well.
4) No.

If you don't mind the minor expense, you can always save various formats, have them print each, see how they turn out, and note the results for future reference.

Cho Da
12-14-2002, 02:23 PM
2) Photoshop Elements will do this. I suspect Graphics Workshop (http://download.com.com/3000-2192-10135052.html?tag=lst-0-1) will as well,
The GIMP (http://www.gimp.org/) will as well. It's free! (http://http://www.fsf.org/)

Obi-Wan Kenobi
12-14-2002, 06:28 PM
Good call. I should have thought of that.

Pseudolus
12-15-2002, 12:14 PM
I found how to do it in PSP - just a matter of clicking on the right tab. Turned out it was on the "Resize image" menu.