You want to print large photos, right? You’ve got beautiful images and printers offer a wide range of showcase image options. Mpix, for example offers gallery wraps as large as 24×36.
You also know that your images can only be printed so large. Say that you wanted a print as large as a billboard from one of your photos. It probably wouldn’t work, because your image file doesn’t have enough pixels to stretch all the way across a billboard.
So how do you figure out the upper limit on print size for a given image? You can check this in either Elements or Lightroom. You just need to know the minimum resolution required by your printer.
Most print labs, or even your home printer manual, will make this pretty easy to find. It’s generally a 3 digit number. Read below for recommendations from Mpix for printing at their lab. But first, do you know what this number means?
When I take a full size photo on my Canon 5Dii, the image is 3744 pixels high and 5616 pixels wide. Multiply those two numbers together and you get 21,026,304 total pixels in the image. That rounds to 21 million pixels. And guess how many megapixels my camera has? You got it, 21.
So, when I take an image, I have 21 million pixels to spread out over a print. 21 million pixels squished into an 8×12 will be tiny and I won’t be able to see them. That makes for a high quality print.
However, let’s say I took an iPhone photo and saved it at a low quality of 400×600 pixels, or 2400 pixels total. What would happen if I tried to print it as an 8×12? Well, the width of 600 pixels divided by 12 inches equals 50. That means that each inch will have 50 pixels across it. I can probably see those pixels and this will be a low quality print. Compared to my full size photo with inches that are 468 pixels wide (5616/12), this is a big difference.
Ok, you get resolution now, right?
Once you find your printer’s resolution requirement, you can use Elements to tell you the maximum size an image can print. If you’re going to crop your image, crop before calculating print size. Then, go to the Image Menu, select Resize and Image Size.
Make sure the Resample box is turned off and select “inches” from the drop down box. Type your printer’s minimum required resolution in the Resolution box, and your maximum width and height will appear in the Width and Height fields. In the screen shot above, I needed a minimum resolution of 240 pixels per inch. If my printer required 240 pixels per inch, I would be able to print my full size photos no larger than 23×15 inches. That’s not exactly showcase size, is it?
When I teach my Elements classes, people always ask about this. “But I have a full-sized camera. I record my photos at the highest quality. And I can’t even print a 20×30 at 240 pixels per inch?”
I agree! So, I asked the smart folks over at Mpix about their minimum resolution and getting the highest quality prints. Here is their answer:
We require that images have a ppi of at least 100, but we recommend 200-300 for the best results. The chart attached below lists our minimum requirements for image resolution.
Photos intended for print should be taken at the highest [pixel] resolution possible for the best print quality. Printing at different sizes does not change how many pixels are in the original image. Lower resolution photos printed at larger sizes stretch the pixels beyond the point of looking clear and sharp. The best printer cannot make a low resolution photo look better than its original quality… but it sure can make beautiful prints when given a high resolution photo with which to work!
Print Size Minimum Image Resolution Wallets 150×250 4×6 400×600 5×7 500×700 8×10 800×1000 16×20 1600×2000 20×30 2000×3000
For the 24×36 Gallery Wrap print, the original file straight from the camera would need to be at least 2400×3600 to qualify for a piece in that size. If the original file is not at least that large, there is not a good way to increase the size without degrading the quality.
A good rule of thumb is to size the image for the print size desired with a ppi of 200-300.
This is great news, right? Mpix requires a minimum resolution of 100 ppi. That means we can get large prints from our cameras! As they say, higher resolutions are better, but not required.
Here’s something else to keep in mind (and this is my opinion – it doesn’t come from Mpix). Those larger sized photos aren’t generally going to be viewed close up, right? You will look at them hanging above the fireplace from across the room rather than standing right in front of the fire. Standing further away, the quality is going seem higher. Remember that a poor quality print looks pixely. You will be able to see the pixels in the image up close, but if you step back, you won’t be able to distinguish between them. I personally would rather print a larger image at 100 ppi than a smaller – we hold wallet photos in our hands to view them, and we probably will be able to detect a lower quality in them .
Lightroom users, you can get the same information. Unfortunately, you have to do the math yourself.
Just like Elements, this needs to be done after any cropping. When in the Library module, look over at your metadata on the right side of the screen. You will see the dimensions there. Divide each by the minimum required resolution to find your maximum print size.
You can view the same info in the Develop module by typing the letter i until you see the dimensions appear in the top left corner of your workspace.
Thanks to Mpix for this great info. Do you guys have other print quality questions? Post them in the comments below and I can send them to Mpix if I can’t help you with them myself.
And, if you need more help with resolution, cropping, aspect ratio, etc, check out this tutorial series right here on Texas Chicks.