Best way to up a photo's resulution.

Hi all,

I'm working on a project in which I will be making 24" x 36" posters of my images. The printer I'm using wants me to send them files sized to 24" X 36" at 300dpi. I'm using a Canon 5DMark II, but even with it's large 21 migapixel sensor, the images are well short of 300dpi at 24" x 36".

So, what should I do?

I know that I can simply increase the file size in Photoshop, but it's always been my experience that doing this degrades the image quality. I haven't done that in a long time, though. Have things changed at all these days? Can this now be done without affectimg image quality much?

Or, am I better to go with an up-rezzing plug-in? Years ago, I tried a trial version of one and it worked well, but I can't remember the name of it. Any suggestions?

Thanks for any help you can give.

Software such as One on One's Genuine Fractals do a very nice job. 24x36 would be no problem. They claim success up to about 6 feet, but I haven't tried that myself.

I wouldn't worry at all about using Photoshop to res up your 5D Mark II images to 24x36. I have a couple of images that size from my 5D (not Mark II). They look great, even up close. Try it on your computer and then look at them critically. You'll be able to tell if they will look decent as prints. Or if you don't believe that, rez them up then take a crop out of the rezzed up image and print just that section as an 8x10 or so and see what it looks like. I think you'll be pleasantly surprised.

Take a look at this other thread about upsizing. I, personally, think Photoshop is just fine, and there's nothing magical about any of the plug-ins out there.

I just used PS CS5 to increase another six scans of quite small photos - snapshots, really - to 48 x 72 inches for wall display at an antique car museum. From more than six feet away, they look amazingly good. PS can't create detail that isn't there, but it does a very good job of preserving what you have got.

Kory, one trick I've used in the past is to upres in Photoshop in 10% increments, which gives you the best shot at preserving detail without having to spend any $$ for a third party program.

PS is excellent; one trick I have learned though is to opt for the maximum file size at RAW conversion. So instead of choosing for the default camera file size opt for the maximum that ACR can handle (25.2MP or so). For the 21MP5D2 this may not make a big difference, but for cameras with less pixels it can. After that upres in PS to whatever you require. I have printed image from a 10MP camera that large and even larger, no props!.

Kory, one trick I've used in the past is to upres in Photoshop in 10% increments, which gives you the best shot at preserving detail without having to spend any $$ for a third party program.

According to the software engineers at Adobe who created the relatively recent Bicubic Smoother/Sharper resampling algorithms, this step is no longer necessary and may even degrade image quality now.
I agree with David (as usual) that PS will do just as good a job as any 3rd party plugin until you start getting into extremely large enlargements.
However, I had a 20"x30" poster created some time ago using a 6MP DSLR at El-Co Color labs. They just had me send in the file at its native resolution and then let their RIP printer software do the upsizing. I was blown away by the quality and have used them ever since. Note that the original file was of utmost quality (tripod, good lens, RAW capture, etc.).

WHCC will do a wonderful job of enlarging these for you. Their print work is supurb, and pricing affordable. I recently sent in a 325kb file, and they enlarged it to a 24 X 36. It is beautiful. On smaller prints say, I need a size 16 X 20 ) I too increase and save the file size to 300mb, but they instructed me not to save and send this file at 300dpi, but to send as was, that their printers will add the extra need resolution. I did call them first so that I could tell them exactually what I wanted.

I'm curious what printer you are using? I've made prints that big, and all I do is send them the native file, which they uprez as needed. (places like Bay Photo and Meridian) The rip software that comes with their very expensive printers should do a better job than any software most of us can afford.

Kory,
You've gotten a lot of good advice from all the listings above, but I'll throw my experience in with the list. I also shoot the Canon 5D II. I prep my images in PS & save as max rez JPG files. For sharpening purposes, I usually reduce the size of the image to 3600 x 2400 & do the final sharpening. I then upload it to MPIX.com. They have no problem printing 24 x 36 prints from that size image & they do fabulous work. A print that large is $45, but they process it the next day & ship it to you. I usually get 16 x 24 prints for any hangings I do. They will adjust the color slightly to match their printer profiles as well, unless you specify that they don't. I recommend you let them do that. I hope this helps.

I use West Coast Imaging for nearly all my prints. I love them, and they do absolutely beautiful work. My only complaint is that I have to size and sharpen all the images before sending them over. They allow you a folder to store the files in, but you have to have as many versions as different sizes you might want. I really like the idea of sending the native file and letting their printer do the upsizing. But I do all mine in Photoshop, and have had pretty good results.

Chris