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Help System > Image resolution

Image resolution and sharp prints

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checking for image sharpness in Photoshop
Check to be sure your image is sharp before you send it to a printer.

Here's how to make sure your image will be sharp. You'll learn about how to calculate image resolution in pixels per inch and how that relates to print sharpness.

Ensure your image is sharp

First, make sure that the picture you want printed is sharp. If a picture is blurry, this whole conversation won’t matter.

So, in your image editing program, zoom in to 100% and make sure that your image is in sharp focus before you send it to any printer.

In Photoshop, click Ctrl/Cmd-1 to zoom into 100%. Look around the image to ensure the details are sharp.

What is a pixel?

100 by 100 pixel image
A 10x10 pixel image, for a total of 100 pixels. We need more pixels! (A lot more.)

We’re going to talk a lot about pixels per inch, so let’s define the term “pixel” first. A pixel is a tiny colored square, made up of a mixture of red, green, and blue, also known as R, G, B.

Red, green, and blue can be combined to produce a pixel that can have millions of different colors..

Every image you see is just a giant grid of lots and lots of these pixels. The more pixels you have, the sharper and clearer the picture will look.

Here’s a picture that’s ten pixels wide, and ten pixels tall. Ten times ten equals 100. So, this is a 100 pixel image, which is obviously not enough pixels.

As the number of total pixels goes up, the image gets clearer and sharper.

 
1000 by 1000 pixel image
A 1000x1000 pixel image, for a total of 1,000,000 pixels, or one megapixel. Much better.

Here’s the same picture at one megapixel, or one million pixels.

And this brings us back to the question about resolution. Many people ask, “How many megapixels do I need in order for a print to look good?”

The answer is that the number of megapixels alone is not enough. You also need to know how big the print will be, and calculate the pixels per inch of the image.

That number will tell you how sharp the print will be.

 
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Pixels per inch versus dots per inch

We print everything at 2400x1200 dots per inch on our world-class fine art printers.

If a print we produce is blurry, it's not due to our printers; it's because the pixels per inch value was low for the print size, or the original image was itself blurry.

Follow what's on this page and on the video at the top, and you'll be thrilled with what you get, every time!

What do pixels per inch look like?

photo of a 300 pixel per inch print
An actual photograph of a 300 pixel per inch print, with zoomed-in inset. The white text is part of the print. The pencil is for scale.

Before we jump into the calculation part, let’s see what different pixels per inch values look like as actual prints.

We produced multiple prints of the same image at different pixel per inch resolutions so you can see them in detail.

Pictured here is a 300 pixel per inch print. The pencil is for scale.

We know from experience that anything over 300 pixels per inch will yield extremely sharp results that exceed the requirements of the most demanding visual artists.

 
pixel per inch comparison photograph
Actual studio photographs of three prints, from left: 550, 400, and 300 pixels per inch. There is no perceptible increase in print quality above 300 pixels per inch.

Here's a photo with three prints, from left: 550 pixels per inch, 400 pixels per inch, and 300 pixels per inch. There’s one at 400, and here’s one at 550. As you can see, there’s not much difference between these and the ones that was 300 pixels per inch.

From 200 to 300 pixels per inch, you’ll get very good results that are satisfactory to nearly everybody. As you approach 200 pixels per inch there might be a tiny bit of softness in very sharp areas that can be seen when you look at the print close up.

 
photograph of 100 pixel per inch print
Close-up photo of a 100 pixel per inch print, with zoomed-in inset. Note the blurriness that's starting to appear in fine details.

As you go down from 200 to 100 pixels per inch, your print will begin to look a little soft and you’ll start seeing jagged edges if you look close up. As you approach 100 pixels per inch, when you look at a print close up, it will look a little blurry.

As the pixels per inch value drops below 100, then blurriness is an issue. If the print is large, for example 20x40, then a number close to 75 might be OK, since the print will be seen from a distance. If the number approaches 50, then only a very large print will look OK, such as a 40x60 print.

Calculating pixels per inch

screenshot of Photoshop's image size box
In Photoshop, click "Image", then "Image size", and the print dimensions will appear as shown.

In order to calculate pixels per inch, you need to know two things:

  1. The image’s pixel dimensions, and
  2. the print dimensions.

Then, to calculate pixels per inch:

  1. Take the larger of the two pixel dimensions, and
  2. Divide it by the larger of the two print dimensions.

To see an image’s pixel dimensions, find the image in a folder. Hovering over the image in Windows will show you the image’s pixel dimensions. Or, right-click on the image, then click “Properties,” then click “Details.” On a Mac, single-click the image file and press Command-I, to get Info, and the file’s pixel dimensions will appear.

Another option is to open the file in an image editing program. If you open the image in Adobe Photoshop, click Image, Image Size, and the dimensions are shown here.

screenshot of an image in Photoshop
This image is 6592 x 3152 pixels. If you want to print the image shown, first calculate the pixels per inch value at the print size you want.

Once you have the dimensions, write them down.

Now think about how big you want your print. To calculate the pixels per inch of any print, take the larger of the pixel dimensions and divide it by the larger of the print dimensions.

Here’s an example. Let’s say you want to print this image at 20”x40”. To calculate the pixels per inch, take the larger of the pixel dimensions, which is 6592, and divide it by the larger of the print size dimensions, which is 40. 6592 divided by 40 gives us about 165 pixels per inch. That’s enough pixels per inch to produce a beautiful, large print. It might be a little soft if you look at it up close, but it will look beautiful hanging on a wall, viewed from a few feet away.

 

Our "Sharpness Checker" can help

screenshot of our Sharpness Checker
Our ordering system has a Sharpness Checker feature, which shows you what your image looks like up close for any print size.

If you want to do this a different way, our ordering system has a cool feature called the Sharpness Checker that can help with all of this if you don’t feel like doing all the math. It will show you what any image looks like up close.

All you have to do is upload an image and pick a print size, and the Sharpness Checker will show you a closeup, so you can determine if the print will be sharp enough for you.

If you have any questions, please allow us to help you. Also, check out our YouTube channel!

Why not place an order today?

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