How do you increase the dpi of a picture?

[rayrey10]

How can I increase the dpi of a picture? We are having some unit shirts made and the printing people said that we have to increase the dpi from 90 to 300.

Any suggestions? Is a special program required (PC or Mac)?

Thanks

[Moparmike]

What software to you have at your disposal? PaintShopPro, Photoshop, etc....
IN either of those two programs, you can adjust the dpi of an image in the image size dialog.
Attached is a screenshot showing the image size box from PSP12. The "Resolution" field is the one you'll want to adjust. pixels/inch is the same as dpi (or dots per inch).

Also attached is a screenshot showing the "Resize/Resample" dialog from Irfanview (freeware and a great little image utility). You can manipulate the dpi settings of an image with it too.
www.irfanview.com

[rayrey10]

Thanks! I don't have PaintShop or Photoshop so I'll have to check out irfanview.com.

On my Mac I only have iPhoto and I'm not sure if that edits pics. I'll check it out when I home tonight.

Thanks again!

[Tako_Kichi]

300 DPI (or higher) is a 'standard' used in the print industry for any image that requires printing. 72 DPI is a 'standard' used for onscreen graphics for visuals that are only ever going to be seen on a monitor/screen.

If your image is currently at 90 DPI you may find the image quality goes down when you resize it to 300 DPI. It's far better to start with a higher resolution and reduce it for the final image than to do the reverse and try to increase the DPI of a low resolution image.

Raster graphics (i.e. photos in .bmp or .jpg format) do not like to be increased in size (they get 'jaggy' and 'pixelated') but can be reduced. Vector graphics can be resized in either direction with no loss of quality.

[Tako_Kichi]

Thanks! I don't have PaintShop or Photoshop so I'll have to check out irfanview.com.

On my Mac I only have iPhoto and I'm not sure if that edits pics. I'll check it out when I home tonight.

Thanks again!
What software was the original image created in? Chances are that it can resize the image directly.

[Cazzie]

Please be aware that increasing the dpi will decrease the print size unless you also resize that with the dpi.

Caz

[rayrey10]

Thanks for the info fellas! The images are going to be used on t-shirts for a race that we are going to participate in.

My boss emailed me the pics and just told me to find a way to increase the dpi to 300, because that's what the guy at the print shop said.

I believe the pic was done in either MS Paint or Power Point.