Converting 72 dpi to 300 dpi

[boxfan]

Hi,

I'm new to IM and image manipulation but here is what I am trying to do.

I have a jpg at 72 dpi and I need to convert to 300 dpi for print. Is this possible? I have read that I can increase the size of the image by 4.166 and then change to 300 dpi which would resize the image back to its original size but I can't see how that would make the image 300 dpi print quality. Wouldn't the quality be the same as the original?

Is this possible?

Thanks in advance!!

[fmw42]

convert image.jpg -density 300 newimage.jpg

see http://www.imagemagick.org/script/comma ... hp#density

[boxfan]

Yeah, the problem with just converting is the image print size is significantly smaller. I need the new 300 dpi image to be the same print size.

Thanks

[fmw42]

I don't use this much, but try -resample rather than -density.

see http://www.imagemagick.org/script/comma ... p#resample

[boxfan]

Cool. I actually stumbled onto that and it created the image in the correct print size with a DPI of 300. Now we're taking it to the printer to see what the print quality is.

Thanks

[anthony]

Just remember that -resample is a resize operator with density adjustment. It resizes the image (number of pixels) so that the image appears to be the same size at the new given density.
http://www.imagemagick.org/Usage/resize/#resample

Of course the IM resize command is extremely good, especially in enlargements, but different filters can also control the quality of the results, but also may need some trial and error or expert help to get right.