Understanding DPI vs Resolution

Hello I am trying to have an image of mine printed professionally. However the print house I have sent my image to has asked that my image be submited at 300 DPI. My image is already 7200 x 4055 pixles with a resolution of 300. My question is what is the major difference between resolution and DPI and how can I go about correcting the dimensions of my image?

Hello,
I am real leary about answering because the dpi/ppi is issue is a very confusing one!!! and i don't want to look like a fool too much...lol.... there thousands of articles and almost none of them explain really in a way the difference..... almost always it comes down between the two parties having a full understanding what of each other...

and when talking is between a printing commercial house and a user..... each one is is in a seperate world......

and the reason is that first the word resolution has a lot of different meanings ie; deminsion resolution, pixal count resolution, pixal density resolution and then you have the problem of people using dpi and ppi interchangably.. and in fact there different... ppi -pixal per inch and dpi- dot per inch are different, dpi is printer specific and ppi is the image density......

so bottom line... is that each side understand the other... and what there really saying...... in your case your thinking in terms of ppi and the other guy thinking interms of dpi...... maybe even lpi ... and there confusion....

always number pixals or pixal deminsions in a image is important...... that will help determine the max printing size for a certain quality of printing... and along with this.... ppi ......example a 640 x480 will get about
3x2" at 200ppi or 2x1" at 300 dpi ....

note: good quality ,when adjusting the images for printing on hp/canon type printers you set ppi of the image to about 300 for epson you set for about 360 ..... in many case you want your image ppi about equal to your printer dpi ....

now.... there no conversion tables for converting ppi to dpi.....!! and that where there generally a lot of confusion..... and this is my understanding.... rule of thumb.... when working with commercial outfits... if there talking in terms of dpi.. multiply that by 2 to get the ppi number you need that they require.... but always verify that with the printing house.....

now.. smiling... i have below some links that I think is representiive on the issue.... just a few out of thoussands that vail... but i hope it helpfulll......

has table to show relation ship between pixal size and printing size with ppi....
http://www.nikonians.org/html/resources/guides/resolution_and_prints/resolution_and_print_size_2.html
http://www.design215.com/toolbox/print_guide.php

general info....
http://www.naturephotographers.net/articles1002/tg1002-1.html

this article,toward the bottom give rule thumb on on dpi and ppi....
http://www.articlejoe.com/Article/The-Difference-Between-DPI-and-PPI/27436

this article i thought was good because it shows a nice relation ship between dpi and ppi and that factor of two that involved...
http://www.deedoos-digital-scrapbooking.com/scrapbook-articles-Resolution.html
this thread work nicely with the article just mentioned...
http://photo.net/digital-darkroom-forum/00EfEw

I apologized for getting too lengthy and probably wordy... smiling.. but i hope it helps you....!!

razorbeam said:

Hello I am trying to have an image of mine printed professionally. However the print house I have sent my image to has asked that my image be submited at 300 DPI. My image is already 7200 x 4055 pixles with a resolution of 300. My question is what is the major difference between resolution and DPI and how can I go about correcting the dimensions of my image?