questions about digital printing

I have a few digital pics from vacation I am thinking about doing some enlargements of for the Rec room. Most of them were shot at 7+ megapixels and file sizes average about 3.5 meg. Is there any type of reference guide for pixels ratio to pic size? I previewed them on my 55″ TV and they look as good as the regular definition TV…but not as clear as the High Def stations as a comparison. Looking to do 16 x 20’s and 20 x 24’s. Possibly one larger poster size. But I don’t want to fork out the funds to find out they are too grainy

You should have no problem printing to the sizes you mentioned with a 7mp camera provided the photos have not been cropped significantly. Just keep in mind that when printing that large, minor quality issues such as under/over exposure, lack of sharpness, digital noise and other lens aberrations will be exaggerated. If they look good on that 55″ screen, they should look great when printed. Check out the online lab Mpix. They make all of my prints and do a fantastic job, but won’t break the bank. Feel free to PM me if you have any further questions.

Hi Randy,
There are rough guides. Say your file is 1000 x 1000 total pixels and you wanted to print it at 10″x10″, you then have 100 pixels per inch for printing. (1000/10) That is good for lower end production. For nice crisp images to be viewed up close, we like to shoot for 300 to 600 pixels per inch for good quality prints at our shop. So, a 20″x20″ finished file could be 6000 x 6000 total. FYI, we have raster image processing software that can upsize pics to any size if you want to go big. Thanks, Signsmith. PS Those pictures look great.