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Digital Printing: Decoding the Relationship Between Pixel Dimensions, Resolution & Print Size

Ever had the disappointment of printing photos that appeared fantastic on your phone but blurry in the printout? As technology advances and phone cameras continue to improve, it has become easier than ever to print amazing photos and images. But doing so requires taking measures to ensure you always get the high-quality prints you’re expecting. 

It can be easy to get lost in the confusion of pixel dimensions, resolution and print size. For those of you looking to better understand this information and avoid wasting money on prints that don’t meet your expectations for clarity and quality, we’ve got the expert insights you need.  

In this article, we'll explain the relationship between digital capture and print output, shedding a spotlight on how megapixels, resolution, pixel dimensions and print size interrelate. With a stronger grasp of these concepts, you’ll be better positioned to achieve optimal results from your fine art and professional photo printing services.

Breaking Down the Basics 

 

First, let’s look at some basic information using the example image below.

 

A cat sitting in the sunlightA cat sitting in the sunlight
This photo was captured using an 8-megapixel iPhone 5s, and its JPG file size is 1.5MB.
Basic image information in PhotoshopBasic image information in Photoshop

If we look at the Photoshop dialog box for this image, the information shows its pixel dimensions, current settings for document size and resulting resolution.

The chain link symbol to the right of these values signifies their interdependence. In other words, as the resolution increases, the print size decreases—and vice versa. Why? Because a digital image lacks absolute size or resolution; it's all determined by the pixel dimensions at which it was first captured. 

That’s why it’s SO important to set your camera to capture images at the highest possible pixel dimensions and quality. It’s always easier to size down (if necessary) after a photo is taken than to try to “create” more pixels in editing after the fact.

Keep in mind that while the example above uses Photoshop, you don't necessarily need it to determine these size values. You can also check the image file properties and perform some simple math.

Image file properties Image file properties

For instance, take the width of your image (in pixels) and divide it by your desired print width (in inches) to figure out what the resolution of the image will be (in pixels per inch, or ppi). With the example above, this looks like:

3264 pixels ÷ 25 inches = 130.56 resolution

So if printed at 25 inches wide, the image will have a resolution of 130 ppi.

Then, you can then calculate the corresponding height (in inches) by dividing the height (in pixels) by the resolution (ppi). This looks like:

2448 pixels ÷ 130.56 ppi = 18.75 inches

A Streamlined Approach to Resolution 

Now, let's shift our focus toward resolution. Because after all, that seems to be one of the biggest questions: What resolution do I need for the best print? 

Here, we’ll discuss the significance of resolution based on the intended viewing or printing medium:

  • For online images or website display, a resolution of around 72 ppi is typically sufficient. Since online images are usually viewed at smaller sizes, a lower resolution helps reduce file size, enabling faster loading times.
  • Printed images, on the other hand, require higher resolution due to their larger physical size compared to screen viewing.

In the context of digital versus physical media, it's worth clarifying two related terms:

  • PPI (Pixels Per Inch): used to measure images on monitors, digital cameras, scanners and other digital mediums
  • DPI (Dots Per Inch): used to measure the physical output of digital images, such as printed photos

While these terms may seem interchangeable, understanding when to use each is important. PPI applies to the digital realm, while DPI pertains to physical printing processes.

So, how much resolution do you need for optimal printing? 

Well, the more complex answer involves additional math and debate regarding factors like the printer’s max DPI, number of color cartridges, type of paper and so on. But we want to keep things simple for you. So, here’s what you should know:

At American Frame, we recommend that your image have a minimum print size of 130 ppi. Upon request, however, we will print lower-resolution images. (Be sure to read the next section on how lower resolution can affect your image.)

On the flip side, there is no max resolution size for our printing services, only a max physical file size of 100 MB. So if you desire your image to be printed at 360 ppi and it is sized accordingly, we can print at that resolution as long as the file size is below 100 MB. 

Here is a helpful visual chart to give you a rough estimate of how large you can print an image depending on the MegaPixel specifications of your camera. We recommend that your image stay within the “better” to “superb” range as shown below:

A print size versus camera resolution chartA print size versus camera resolution chart

More information like the chart above can be found here.

When Low Resolution Results in Pixelation

Now that we’ve laid out the insights for recommended resolution, there remains the question of what happens when your image is too small. Sure, we can go ahead and print it, even if the resolution is lower than our recommended 130  ppi. But that may result in pixelation—which is not conducive to quality prints. 

Ever noticed how an image can look smooth and seamless when you're zoomed out, but as you zoom in, the individual pixels that make up the image become more visible, revealing jagged edges? This is pixelation, and it occurs when an image is blown up to a size at which the pixels become discernible. 

To see this in action, let’s use our original cat image.

Pixelation in the cat imagePixelation in the cat image

To achieve the recommended resolution of 130 ppi, this image has a maximum print size of 25 by 18.5 inches. If we wanted to print larger at, say, 40 by 30 inches, the resolution would drop down to 81.6 ppi. With this decreased resolution, we would start to see pixelation. And the larger we increased the inches, the more apparent this pixelation would become.

If you find yourself in this conundrum with one of your images, we recommend ordering a Resolution Proof. These proofs allow you to have an 8"x10" section of your image printed at full size so you can see it up close and decide for yourself if the pixelation is too apparent. If it is, you have a couple of options:

  • You can choose to print at a smaller size that maintains a higher resolution, thereby reducing the visibility of pixelation.
  • If you have access to editing software, you can consider a technique called “up-ressing” or “ressing up.” This is basically a software fix to create or add extra resolution to a digital image.
Original close-up of the cat's whiskers next to the up-ressed versionOriginal close-up of the cat's whiskers next to the up-ressed version

It's important to exercise caution when using the up-ressing method because the software essentially generates pixels that weren't originally there. As a result, the overall effect tends to blur the image more than a standard print. The reason for this is that larger prints are usually viewed from a greater distance, and the blurring effect becomes less noticeable when you step back and view the print from afar.

Digital Prints That Delight

To order high-quality prints that meet your expectations, understanding pixel dimensions, resolution and their impact on print quality is crucial. The more pixels your image has at the outset, the more clarity your printout will show.

Remember to set your camera to capture images at the highest possible pixel dimensions and quality so as to access the greatest number of printing size options. And be sure to follow the recommended parameters for resolution when printing. When in doubt with lower-resolution images, consider ordering Resolution Proofs to assess pixelation (and color) up close, and make adjustments accordingly. 

With this knowledge and insight, you'll be able to unlock the full potential of digital printing services and create stunning prints that showcase the beauty of your images.

Ready to begin your next printing project? Start here.

 

May 3, 2023
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