I made a collage, intially intended for the web. I made some
modifications in paint because i was new on photoshop elements, and
figured it's just for web use no big deal. Now the collage I made
is needed for print use, the collage was saved as a jpg and is one
file. I have converted the jpg to psd, but cannot figure out a way
to modify image size to 300 dpi. If it is possible how do i do it
in Photoshop elements? Will it actually hurt the quality when it
goes to print?
The number of pixels the image has are what will determine
its quality. Changing the "resolution" to 300 won't change anything
about the image.
If your image is "big enough" to print at the size you want
at the resolution of the intended output device, then great. If
not, then changing the document from 72 to 300 dpi won't change the
image at all. You can't add pixels to it to make it print better.