Wow Dude….He clearly states he is talking about online and print. Everything he goes over is very relevant if you’re dealing in some combination of these two formats. Reading comprehension my friend…try it.

If my images came out as 72 DPI and the graphic company needs it higher quality, is there a way to change it or do I need to reshoot?

dpi is important when scanning, it is irrelevant when printing to a photo printer.

you are as misinformed as the original author. First dpi is only important in graphic arts – as in when you go to print on a printing press. It makes no difference at all in photographic arts when you print to a photographic printer. This whole 300 dpi for good reproduction in photography is an urban myth propagated by those that think they know more than they actually do.

It’s origin goes back to the first Apple Laser printers and what you needed to do so that line art (Black and White – no grey) angled lines would print with no apparent stair stepping. It NEVER applied to half-tones. For half-tones you would screen the print on a copy camera and the line screen you would use depended on the press and the paper you were using. Typically you would use a 65 line screen for newsprint on a web press, but if your press was better, or you were printing on a higher grade of newsprint you could use a 85 line screen. For hard gloss paper on a sheet fed press like you would see in magazines then a 133 line screen could be used.

The above is over simplified but accurate.

If you go to the library and pick up old copies of newspapers and magazines and use a loupe you can actually see the screen. And you will see that in even the lightest greys the dot size is the same as the deepest blacks. It is just the space between the dots changes. Light areas fewer dots, darker areas more dots. With white being no dots and black being all the dots bleeding together.

But even in the graphic arts industry that is no longer as relevant because the new imaging equipment uses a different type of screening so the dot patterns have changed but that is for a different story.

Now for photographs on a photo printer. No dots needed. The best way to explain the difference is look at a Georges Seurat painting and a Rembrandt painting. Seurat used a series of distinct dots (like a printing press) while Rembrandt used brush strokes. Today’s modern photo printers are more like Rembrandt and so the dpi of the original is not relevant – only the total number of pixels, and you do not need nearly as many pixels as people are led to believe. to use your numbers that same 2400×3000 image that you say you need for an 8×10 will also print a perfect 24×30 inch print on glossy paper on something like a canvas that will give you an excellent 48×60 inch image. I have actually had a 2000×3000 image used to create a mural that measures 16 feet by 90 feet.

If you are old enough, and you don’t have to be that old, to remember the very first commercial digital cameras that cost in the range of $20,000 but only created a 1 MB image, and they were used to create thousands of billboard sized images across the country.

Well if you have a camera capable of producing a 6 MB image, then you have all the pixels you need to create any sized photographic print that you want. No fancy resizing, upsizing or other fancy technique needed. Just send the full res file to the printer.

and for those of you that are saying NO, you need that 300 dpi, spend some money and see for yourself. Take a 2400×3000 image to your local costco or walmart and have them print a 24×30 poster. If you want you can set the dpi to whatever number you want – just do not resample the image. Run it a 100 dpi, 300 dpi, hell go all the way and run it at 600 dpi – look at the resulting prints at normal viewing distances – you will see NO difference.

Hi Esther, as far as I know there are no printers with a higher resolution than 350 dpi. So you would be getting a smaller image (becasue the distribution of pixels would make them closer together) but achieving no sensible increase in the quality of your print. I hope that helps.

@debragroninger:disqus
These are the conversions for you into inches.

3456 x 460px = 48 x 6.389inch
4608 x 456 = 64 x 6.333in
3264 x 2448 = 45 x 45.333in
2272 x 1704 = 31.556 x 23.667in
1600 x 1200 = 22.222 x 16.667in
640 x 480 = 8.889 x 6.667in
4608 x 2592 = 64 x 36in

I hope this helps you with the size you need to print.

@disqus_GBsRFFeKCS:disqus
Hi Clifford,
If you were to change your image from 56″ at 72dpi to 5″ at 300dpi, you would be best to do this at once. If you were to change it to 5 x 5 at 72dpi first and then try to upscale it to 300dpi, you will lose image quality.
If you change it at the same time you have more pixels to play with at 56″ (4032x4032px).
If you were change your 56″@72dpi to 300dpi for print, you can have a max print size of 13.44inches without losing pixel quality. So that leaves you room to play.
I hope that helps.
Cheers