# Still confused about PPI/DPI (not verses each other)



## prodigy2k7 (Jul 17, 2008)

Okay I did some searching and I understand about printing and not. What about just the default? Like what does a computer monitor show? I often do prints at target because its quick for 8x10's if nobody is there. Do you think they print at 300dpi?

I dunno im just all confused, im confused i dunno how to ask a question my mind is just blank! ha...

Is there even a default for PPI on your images? Or is DPI/PPI just for viewing an image and your "output" device chooses how to display ur image such as your computer monitor or a printer?


----------



## Mike30D (Jul 17, 2008)

Try this.... DPI and PPI

There is no "default" for ppi, it depends on the size of the file.


----------



## nynfortoo (Jul 17, 2008)

Monitors generally display at 72dpi.


----------



## davebmck (Jul 17, 2008)

Your camera has a fixed pixel size in height and width.  For instance, my camera is a 10mp camera and has a pixel size of 3888 x 2592.  You can set your default resolution on your camera to whatever you want to.  I have mine set to 300ppi and I think that is pretty common.  When you view your photo in your software (or print it), it will set your picture size by dividing the pixel size (height and width) by your resolution.

Most software has a resample option.  If it is turned off, your pixel size is held constant.  So if you change your picture size, you will increase or decrease your resolution accordingly.

If you turn resample on, it will permit the software to change your pixel size.  If you reduce your pixel size, you throw away pixels.  That's generally not a problem.  If you increase your pixel size the software must create pixels via some complicated algorithms.  This "upsampling" can degrade your picture, so be cautious when using it.  If you resample, typically, your resolution is held constant, so if you increase your picture size, you will add pixels (upsample).  If you decrease the picture size, you will throw away pixels.

As far a printing is concerned, most people say that 240ppi is fine for inkjet printing.  If you are going to a professional printer 300ppi is prefered.  As mentioned in a earlier post, 72ppi is all most monitors can use.


----------



## astrostu (Jul 17, 2008)

There is nothing in the photograph that dictates DPI.  Only PPI.  The two have nothing to do with each other as far as going from a digital file to a printed copy.  I have no idea what Target uses, but you could try asking them.  It's unlikely, though, that the people who run the printer actually know.

And contrary to popular belief, most newer monitors these days are NOT actually 72 ppi.  I just measured mine and it's around 100 ppi.  An older monitor I have (from 2001) is around 80 ppi.


----------

