Printing "large"

[aguerra.1993]

Hello everyone, I have searched and read on the topic but I am still having some trouble understanding things when it comes to printing. I have an image that after all editing and cropping is 4941 x 3294. I shot it with an 18 mp camera if that makes any difference. I am wondering if I can have this printed at 20" x 30" and if I can, what ppi should I use? I exported it from lightroom at 300ppi but I am unsure what the difference would be if I export it at 240ppi or less. Any info would be greatly appreciated, thanks!

Edit- This print will be for my living room, I guess the viewing distance would be a couple feet.

 

[The_Traveler]

The ppi is not relevant.
When you set the print size it will adjust.
From Printing > Which Resolution? > Long Answer > 1 - Print Size & Viewing Distance

Now, if you invert this, at 150 ppi of the print, people could view at about 27" and get the impression of sharpness, even though they wouldn't be seeing the entire image in their FOV.

Some of this depends on the sharpness of the print and how well you sharpen for printing.

 

[KmH]

4941 x 3294 pixels = 16.28 MP.
You cropped away 1.72 MP.
The only editing that affected the image resolution (4941 x 3294 pixels) was the cropping.

4941 px / 30 inch = 164.7 ppi - The print resolution (ppi) needed to print a 4941 x 3294 px, 3:2 aspect ratio photograph as a 30" x 20" print.
(Note: 4941 / 3 = 1647. So does 3294 / 2 = 1647. APS-C and full size (35 mm) image sensors have a 3:2 aspect ratio).
3294 px / 20 inches = 164.7 ppi

Basic, grade school math.
A lot of daily life is a word math problem.

 

[xenskhe]

You want a 3:2 image if it isn't already. I'd use 300 ppi minimum (the more the merrier). 30x300, 20x300. If you need a way to upsize, try FastStone Image Viewer and use 'Mitchell' as the resize method.

 

[xenskhe]

So exporting the image, should I lower the ppi to 165 or should I leave it at 300?

As long as your file is 300x30 by 300x20 you're good (assuming you want 300ppi). The export thing..sorry no idea.

 

[xenskhe]

Leave it at 300ppi. Then right click the image, view propoerties of the file, and check resolution is what you want.

 

[aguerra.1993]

There seems to be 2 sides, haha. One swears by 300 ppi or more and the other says it's not relevant.
If the image I exported with the dimensions of 4941 x 3294 at 300 ppi does it make a difference if I send that file to be printed or export another version with less ppi?

 

[xenskhe]

If you want a 300ppi, 30x20" image, the file needs to be 9000x6000 pixels resolution. Anything smaller will be less ppi at 30x20". you can either scale-up your file to 9000x6000 or use it as is for a lower ppi 30x20"print.

 

[aguerra.1993]

Oh ok, that makes sense. I don't think I can upsize it that much without losing quality. Thanks for your help!

 

[xenskhe]

You on a Windows PC? FastStone Image Viewer: Resize 200% (Select Mitchell). You won't see any loss of quality. Takes about 10 seconds to do it. Will give you a 9882x6588 image.

 

[Dave442]

One of the issues is that there are a ton of comparisons of images between different cameras shown on the monitor, but not that many comparisons of the actual printed images.

I just had six prints of this size made from my 10mp D200 and standing a foot away there is no visible pixilation. I knew these images would be printed large when doing the post processing so they were not cropped more than a slight straightening on a couple of the images and processing was all done in LR.

It would be interesting to have the same shot from a higher mp camera printed out and put them side by side. At some point I will do this, but just wondering if someone else has done this.

 

[KmH]

If you want a 300ppi, 30x20" image, the file needs to be 9000x6000 pixels resolution. Anything smaller will be less ppi at 30x20". you can either scale-up your file to 9000x6000 or use it as is for a lower ppi 30x20"print.

Yep.

There's that pesky basic math stuff again.
30 inches x 300 ppi = 9000 pixels.
20 inches x 300 ppi = 6000 pixels.