Photo Resolution: Sizes Needed for Printing Your Images

We are often asked what quality an image needs to be for printing. This is a great question, because sending a low quality image will result in a disappointing, low quality print. Image quality includes many factors of course, from composition (the way you set the image up if you shot it), to color choice, lighting, etc. These are really important factors when capturing original artwork, and that’s why we offer professional capture services. But here, we want to discuss the size and resolution of your images. Size isn't usually an issue if the image is to be printed in a memoir but a significant factor in a 60"x40" canvas. Let’s assume you’ve taken a fabulous image, and are just looking to make sure it doesn’t appear “blurry” or “blocky” when printed. How can you be sure it will print crisp and clear?

One SIZE Does Not Fit All

Image size is the most important factor for large prints. In the most simple terms, is the image you are giving us to print large enough to fill the space you want it printed on? If it is not, it will need to be stretched or “blown up” somehow, and that always results in quality loss.

The good news is, if you follow some basic guidelines, this should never be an issue for you. It can be very, very simple. We’d like to start with the simple, which will apply to most of you, then offer some more specific help for more specific situations.

The Really Good News

Here is the really good news folks;
If you have bought a digital camera in the past few years, and you have taken your images at the highest quality setting of that camera, you images will print just fine.

Too easy right? Let’s look a bit closer. Any camera with a good lens, good sensor, etc, that is rated at 5 megapixels or more can give a great 8 x 10 inch print, and even a decent quality 16 x 24 inch print. The 16 x 24 inch print won’t look as good when you are standing 1 inch away from it, true. But at a comfortable viewing distance, it will be just fine, even from a 5 megapixel image. Even today’s cell phones offer cameras with 5 megapixel cameras! Just make sure you are taking the image at HIGH QUALITY setting on your camera. The file format of TIFF is usually best for us, but we can also use high quality JPEG or JPG images.

Hang on  Megawhatsels?
Defining Some Terms

You got me – I said that you wouldn’t need to get complicated. And you’re probably right. Let’s review that good news; “If you have bought a digital camera in the past few years, and you have taken your images at the highest quality setting of that camera, you images will print just fine.”

This is true most of the time. But if you have a special situation, or just want to learn what’s going on “behind the curtain”, some basic understanding of terms doesn’t hurt. Let’s get to the terms first, and if you prefer you can skip to those “special situations” below.

Megapixels

What really matters for printing an image is it’s size. Digital images are measured not in inches, but in pixels. That is, the amount of individual digital dots of color it takes to build the image on a screen. A 10 megapixel image would have 10 million of those pixels (megapixel = million pixels). The way you get at that 10 megapixel number is similar to calculating the square footage of a room. Width x Height. So a 10 megapixel image could be 5000 pixels wide by 2000 pixels high, for instance (5000 x 2000 = 10 000 000 pixels). It could also be 3300 pixels wide and 3000 pixels high (3300 x 3000 = 9,900,000 pixels – rounded up to 10 megapixels).

Megapixels are important, but not as important as the electronics store salesman would have you believe. Why not? Because buying the best available is not wise, unless you need the best available. Buying what you need for your uses is what counts. We have seen images that had significant resolution but were grainy and flat when printed at the size requested. In this case sensor size was an issue.

ALL cameras made today have more than enough megapixels for common printing situations (and yes, that includes large canvas prints). You’ll have a hard time today buying a new camera with too few megapixels for a decent size print. Really. 10 megapixels is a common rating, with 18 megapixels and up becoming standard. Those are plenty big images folks. 

Tip: When buying a new camera, don’t focus on megapixels. There are enough. Focus on other factors that effect the visual quality of the images you’ll be taking, like the quality of the lens, performance in low-light (if that matters to you), color quality, image stabilization, handling, etc.

Pixel Dimensions

When we are asking for a certain size of image, we are asking for it’s pixel dimensions. That “3300 x 3000” number. When you provide us with that number, we can calculate how large the image can print at the settings we use on our printers here at PageMaster.

If an image is larger than the minimum dimensions we need, there’s no problem. If it is smaller, it still may be OK (if you cannot retake the image), but there may be some quality loss issues. If an image needs to be re-sized, it’s better that you let us re-size it for you here than do it at home, as we can do it quickly with the least quality loss and we know the best settings for our print environment, such as the PPI we are looking for (minimum of 144 PPI, 240 OK, 300 best) at PageMaster.

PPI/DPI

These two terms, DPI (dots per inch) and PPI (pixels per inch) are often used interchangeably, but they are not the same thing.  We’ll use PPI here, but know that some older programs may use DPI to define it’s “resolution” for an image. We use PPI because it actually tells us most directly how many pixels will be printed on each inch of paper. Pixels per inch. It’s how we determine the ideal pixel dimensions needed to print your image on a certain paper or canvas size. DPI is used to measure printer resolution and you need many dots to faithfully reproduce a pixel.

An example may help. Let’s say you want to create an art card of your latest photograph. Let’s assume the card is going to be 4 inches by 6 inches. At PageMaster, we work with a minimum of 240 pixels per inch (PPI) for these art cards. So, for every inch of printed space, we should have 240 pixels of image data to get the best results. This requires simple multiplication. Let’s start with the width of 6 inches. Multiply that by 240 and you get 1440. The image should be 1440 pixels across. The height? 4 inches x 240 PPI = 960 pixels. The image you provide us should be at least 1440 pixels by 960 pixels for a 4 x 6 print. We know this because we want an image with a minimum resolution of 240 PPI.

So, what is the megapixel count of that image? Hold on to your seat … a whopping 1.4 megapixels (1440 x 960 = 1382400 pixels = 1.4 megapixels). Your cell phone camera can likely do that folks. That’s why we didn’t want you to sweat the details. It’s not that the details don’t matter, it’s just that the details are most likely fine.

Let’s try one more example, at a larger print size of 11 X 17 inches.

11 x 240 = 2640
17 x 240 = 4080

Pixel dimensions required = 2640 x 4080 for an 11 x 17 print.

Megapixel count = 10.7

Again, almost any camera sold today will give you 10 megapixel images.

Photokaboom offers some great calculators for doing just this sort of thing, which you can access here. The site as a whole has many tips you may find useful for digital photography.

Viewing Distance

You can see that we are already needing some fairly large images for a 11 x 17 print, but all that really means is that the print will look as clear as the file itself when you put it right up to your nose and stare. Of course, you don’t do that. To take in the whole image, you sit back a bit. The larger you print the image, the further away you will view it. Because no one looks at 20 x 30 inch canvas print from one inch away, you can get away with even smaller pixel dimensions in your file. It’s true that it won’t look perfect up close, but it can look surprisingly good from a comfortable viewing distance, even if your file isn’t quite large enough. I once printed a 3 megapixel file on a 20 x 30 poster and, hanging in my living room, it looked perfectly clear. Next time you go for a walk, step up really close to a billboard and witness the magic of viewing distance. Chances are that billboard will look very blurry up close. Driving by, of coarse, it looks fine.

File Formats and Compression

A file format is the way your file is packaged to be read by computers. More simply, it refers to the extension – the text after the dot – in your filename. So “house.tiff” would be a TIFF file. “house.jpg” would be a JPEG file (these can have the extension of either .jpg OR .jpeg). We use TIFF files internally and high quality JPEG files when file size matters.

Image file sizes can be huge and there are two basic ways to reduce the size. Lossless and Lossy. Lossless methods reduce file size without changing the image quality. Lossy formats do reduce the image quality.

Each time you make a change and save a JPG file you will loose a bit more. The quality level you choose when saving and the number of changes are important. You can end up with an unusable image even with high resolution. Work in a lossless format and use JPG for the final files when size matters.

TIFF and PNG formats use an algorithms and are lossless. Enabling compression in a TIFF file will generally reduce the size by half. From a risk perspective a damaged compressed file may unrecoverable whereas a damaged uncompressed TIFF file will have missing bands. LZW is our default.

High end digital SLR cameras will take “RAW” format photos. These are great for you, because you can have finer control over the colors, sharpness, etc of the photo in a photo editing program that supports RAW file formats. RAW file editors are generally nondestructive – your changes are rendered on export from the original with no quality losses. RAW files are not great for us however, because we will likely get the unedited version of the image, which may lack some enhancements you have made. If you do use a RAW editor, like Adobe Lightroom, Apple Aperture or ON1, please export your images as JPG if e-mailing or uploading, or TIFF if sending on a disc or USB stick, before sending them to us or other service provider.

If you want to reproduce an image on a really big scale, let’s talk. Our 12 color wide format printer can print 44" wide (we do large canvas reproductions and fine art paper prints), but there is a limit to sizes that we can print. A simple laser test print is the best indication of if your image will handle the size. Once a size is determined, we will look at the ideal pixel dimensions for your file and may discuss factors like viewing distance with you if needed. 

You’ve cropped your image

This is the big “what if” that could very well invalidate that simple rule we mentioned off the top. Let’s say you took an image of a beautiful Banff mountain, but there is a bear-safe garbage can just on the right edge of the image. Photo editing software (and even many cameras) will allow you to crop an image, selecting just a portion of it and erasing the rest. This is like digitally trimming pieces of the file off. Because you are cropping away some of the image, the image is going to get smaller. A 10 megapixel image is only 10 megapixel image if you use the whole thing. If you crop away 20% of that image, it is now an 8 megapixel image. This will likely not cause problems in most situations, so long as you start with a large file (pixel dimensions) and use most of the image in your final crop. If you crop one face out of a whole crowd, however, the image of that face alone may not be large enough to print at a decent quality.

Your image is from the internet

If you’ve got an image from the internet, and it is not made specifically to be printed, it will likely print poorly at larger sizes. Without getting too technical, an image 1000 pixels wide and 1000 pixels high takes up much more space on a screen than on a high-resolution paper print. Respecting copyright and supporting creatives is important. Just like you want your work to be acknowledged and paid for (so you can create more great work), treat others with the same respect.

Most stock photography websites provide high resolution images suited for printing, but images that have been found elsewhere on the web are likely not good candidates for print.

Your image was taken at a low quality setting

You now know how to get the right images from your camera going forward, but what if you have an older image that you took before you became such an image expert? Unfortunately, there is no way to make the image larger without losing some quality. There are some neat tricks we can try, but if the image size is too small, we cannot guarantee a magic bullet solution. That being said, it’s still worth a try. Contact us with your questions.

You are buying a new camera. What should you be looking for?

Let us repeat – you can virtually ignore the megapixel buzzword. It matters, but on most cameras sold today, you’re well covered with a number of 10 or even higher. What you should be looking at is how the camera will perform in the situations you will most often be using it (lots of low-light photos, for instance?). What is the quality of the lens? How much zoom is provided (ignore digital zoom – it really does nothing but crop your image in the camera, making it a smaller size image)?

If you are going to be doing photography seriously, taking and printing a lot of images, and selling those images, we encourage you to get a Digital SLR (single lens reflex) camera. The investment may be a bit higher, but the flexibility and image quality (not image size) more than makes up for the price difference. These are the big black cameras with lenses that screw of and can be changed. These cameras work much like the SLR cameras of the past, focusing on photography basics like aperture, shutter speed, ISO light sensitivity and more. These basics are invaluable for you to learn, and you can get a lot of help online (Google is your friend), or by taking a low-cost photography course in your city (here in Edmonton, courses are offered by the City Arts Centre, among other places).

More Questions?

We’re happy to help. Get in touch with us today and play “stump the printer”!