Resizing 16x20

[tara_ratliff]

<p>If I am going to make a 16x20 from a 10 megapixel Nikon D200 camera, what does the resolution need to be? I always save them to 720, but someone told me that was for a billboard size. Also was exactly does ppi mean compared to just 720 resolution? </p>

 

[alan_olander1664878205]

<p>The pixel dimensions of an image from a D200 are 3872 x 2592. If you print that image at 300ppi, the print would be 12.9 x 8.6 inches (3872/300 by 2592/300. If you printed at 100ppi, the print would be 38.7 x 25.9 inches. PPI means nothing until you print. As for saving at 720, I don't know why you'd do that, but it doesn't matter anyway. The pixel dimensions are all that matter.</p>

[alan_olander1664878205]

<p>Just to add, if you print at about 160 ppi, you can get a 16 x 20 (you'd have to crop some off the long dimension) using the native pixel dimensions of your D200. That may not give you a quality print, so you could up-rez the image some.</p>

[tara_ratliff]

<p>I guess I am still confused. I still don't know what I am supposed to save it as for a standard cd for customers to print from. When I go to image size you need to change the width and height in inches as well as the resolution. So what resolution do I save at? One customer wants a image file to be a 16x20, so I changed the inches to that, but what do I make the resolution to on the cd? </p>

[alan_olander1664878205]

<p>Perhaps this would be a place to learn about what you are asking:<br>

<a href="../learn/resize/">http://www.photo.net/learn/resize/</a></p>

[Mattman944]

<p>Like Alan said, the ppi really doesn't matter. But since the file needs to be saved with some ppi, I would use 300 ppi. If the customer isn't smart enough to change the ppi to get the print size he/she wants, they shouldn't be making prints.</p>

[Spearhead]

<p>Give the photos at the resolution (horizontal pixels by vertical pixels) they are when you are finished working on them. If they are 3000x2000 when you are done (just using round numbers to be easy), then give them that. The ppi setting will be irrelevant with the printing services most people use, they are adjusted at the printing end, not the user end. If they are doing their own 16x20 inkjet printing, then they have a fairly sophisticated setup and should know how to deal with the printing. </p>

[tara_ratliff]

<p>Well, they will either be taking the cd to a one hour photo kind of place or a professional lab. But one of my customers did bring it to a professional lab and he was complaining about my resolution being at 720. And he said he couldn't print or change it cause it was too large and that i needed the ppi at 200, but isn't that the resolution? I figured he could do that, but I guess not... </p>

[alan_olander1664878205]

<p>If the professional printer really knew what he was talking about, he wouldn't be complaining about the ppi. All he would have to do is change it. </p>

[StuartMoxham]

<p>He complains about it Alan because he likely gets hundreds of bloated files every week and often hundreds of bloated files from one customer for a printjob that the customer needed yesterday. They bog down the computer that is driving the lab or lightjet. He may not have photoshop installed on that box as it is just for the lab or lightjet so then he has to go to another box to resize the images and then transfer the files back it's all work that has to be done on top of the printing.</p>

[henry_s3]

<p>A long time ago I read about a formula to work out picture sizes and required pixels for certain sizes. It seems to work for me (maybe I'm just too dumb to understand all the other explanations!)<br>

If I have a picture of 1600 x 1200 pixels and a resolution of 300 DPI, I can calculate the picture size in cm as follows:<br>

edge length in cm = (edge length in pixels/resolution in DPI) x 2.54<br>

So my example would give 1600/300 x 2.54 = 13.54 and 1200/300 x 2.54 = 10.16<br>

So the picture would have the size 13.54 x 10.16 cm<br>

Conversely, if I require a picture 10 x 15 cm, I can calculate it as follows:<br>

edge length in pixels = (edge length in cm/2.54) x DPI<br>

This would mean a 10 x 15 cm picture requires 1181 x 1772 pixels.<br>

(I've used one inch = 2.54 cm as where I live - almost - everything is measured in cm)</p>

[alan_olander1664878205]

<p>The printer would receive no more of a bloated file with an image that was 3000 x 2000 at 300ppi than he would with a 3000 x 2000 image at 720ppi. The image is exactly the same file except that it is tagged with a different ppi. If someone re-sampled an image, then yes, it would become bloated.</p>

[StuartMoxham]

<p>He would though if it was 12x18 inches at 720ppi. People bring a whole mess of bloated files for printing and do weird things like make huge scans from 8x10 inkets. They do these thing because they heard something somewhere from someones uncles brother that the big file will make a better print.</p>

[alan_olander1664878205]

<p>Stuart,<br>

I agree that in your example that would be a big file. Unfortunately, most people don't understand ppi, pixel dimensions, resizing, etc., including some who are shooting for money.</p>