What Is Image Resolution? Why Does It Matter? :: Digital Photo Secrets

What Is Image Resolution? Why Does It Matter?

by David Peterson 7 comments

If you’ve been around since the beginning of digital photography, you no doubt understand how much progress we’ve made. Today’s models make the first digital cameras look incredibly weak, and the reason is resolution. For a lot less than you would have paid back then, you can get a digital camera with ten times the resolution. Does that mean your images will be ten times better? To answer that question, we need to get a better understanding of what resolution is and what it isn’t.

[Photo Above By Andrew Magill]

Think of resolution as “image quality”

Put into some very basic terms, resolution is the quality of the image. As the resolution goes up, the image becomes more clear. It becomes sharper, more defined, and more detailed as well. Why is that? Because there’s more information in the same small space. Your computer, laptop and your smartphone (if you’re lucky enough to have one) both have image resolutions. There is a certain number of dots in the space that is the screen. Put even more simply, the more dots you jam into the width and height of the screen, the higher the resolution. The less dots, the lower the resolution.

If you remember those old computer monitors from the 90s, you'll remember how blurry the images were. These days, most basic laptops and LCD screens have a much higher resolution. You get more detail in the space of your screen because there are more dots to display the details of the images. That’s all resolution is. It’s the number of dots (i.e. pixels) in any given space.

Piecing it together even more

Sometimes a good example does what words will never do. So let’s create an image of the letter “a,” going from the lowest possible resolution to something much larger than that. At a resolution of 1 by 1, (a square that’s one dot by one dot), we end up with an “image” that looks like this:

Well that’s pretty boring. Why no letter A? There is no letter A because there are no more dots than the single dot we used. So let’s bump up the resolution and go with a 10 by 10 square.

Alright. That looks like an A. Hopefully you can see what’s going on here. The more we increase the resolution of the graphic, the clearer the A becomes. Now let’s multiply the 10 by 10 resolution by 5 to get a 50 by 50 square.

That’s closer to what we want, but it still doesn’t have that crisp quality I’m used to seeing on my laptop. To get that, we’ll need to increase the resolution even more. Let’s multiply it by 2.

That’s better. Actually this image is at full resolution for the screen I’m using to view it. That is to say, I cannot improve upon its quality because my laptop cannot display images at a higher resolution than that.

Cheating Resolution

You can cheat resolution and make an image seem smoother than it otherwise would by using a technique known as anti-aliasing. This smooths out the jagged edges in text, or angled lines in your image. I've turned on anti-aliasing for this last 'A' and you'll see it appears smoother.

Also, it's possible to 'cheat' and that's what LCD screens do - each pixel is made up of small red, green and blue sub-pixels like the image at the top of this article. By cleverly changing the amount of red,green and blue, a computer screen can manipulate the sub-pixels to give the illusion of having a higher resolution. That results in a better image. Microsoft calls this Clear Type and it's mostly used for text.

The difference between print resolution and screen resolution

Resolution starts to become a bit more complicated when you want to print your images. Now, instead of dealing with a screen that doesn’t change, you have the option to print the image at any number of resolutions. Which one is right? What should you use to get the best quality?

First of all, realize that resolution oftentimes takes a back seat to the paper you’re printing on. If you don’t have the right kind of paper, the ink will bleed, and it just won’t matter how detailed you’re trying to get.

Print resolution tends to be much larger than screen resolution. That’s because the ink dots when printing can be much closer together than normally seen on a screen. You can fit more 'pixels' in a printed photo than you can fit on a screen.

Because of this, you should never print your image at the same resolution of the screen you are viewing it on. That’s a fast way to get some very strange results. Most computer monitors display images at 72 dots per inch. When you print, you should be anywhere from 300 dots per inch up to 1,800 dots per inch with the most sophisticated equipment.

What does resolution mean to the photographer?

Today’s digital cameras already have all the resolution you will ever need, so don’t have to consider image resolution nearly as much as you once had to. You can easily get a digital camera that meets the basic resolution requirements, which is somewhere around 6 megapixels for most printing and viewing. You only need to consider a beefier camera if you always need to create larger poster-sized prints.

Also, because most memory cards store tons and tons of images, you should never feel the need to conserve space. Go ahead and snap those pictures at full resolution and don’t modify the resolution settings later on. Doing absolutely nothing is the best way to ensure great quality so far as image resolution is concerned.

I haven’t changed the resolution, but my images are still blurry. What’s wrong?

Nothing is wrong with the resolution settings on your camera or your computer monitor, but there are a number of other things that can wrong in the course of a photo shoot. You may have shaken the camera too much while taking the picture at a slow shutter speed, or you could have focused on the wrong part of the scene. Either of these will create blurry images even though your camera is capable of getting 10 megapixels.

This happy dog isn’t blurry because the camera has a low resolution. The dog is blurry because the photographer and the dog were moving while the picture was being taken.
Photo By Flickr User texasrexbobcat

The one mistake that totally destroys resolution!

As a last word of advice, I want to remind you not to do this one thing that will totally destroy all quality in your images. If you ever need to crop an image or make it smaller, never ever resize it back up to the original size! Doing so will kill the quality of the image, and you’ll be left with nothing but a blurry mess. Just remember that you can always go down in size, but once you do, it’s irreversible. You can’t go back up. That's one of the main reasons I recommend you always keep a backup of your original photo when editing.

And long-time readers will know I recommend avoiding the “digital zoom” feature on any cameras as well. Digital zoom is a bogus feature that camera makers build into their cameras to make them seem more capable. When you use the digital zoom, you aren’t really zooming in. You’re simply magnifying the image that’s already stored on the camera. It’s no different from going into Photoshop, cropping the image, and then resizing it back up. Avoid it, and you’ll always have crystal clear images.

Resolution isn’t too hairy of a concept once you break it down into the fundamentals. It’s image quality. Plain and simple. As it is with many things, doing nothing and avoiding the big no-no’s is often the best course of action.

Most people think this post is Awesome. What do you think?


  1. John Scriber says:

    Hi David,
    I am about to embark on the daunting ask of scanning all my pre digital photos and slides, and since starting my research I have found that I can actually scan the negatives to get even better resolution. I have been searching information on scanning, types of scanners and of course information on pixels, resolution and dpi ? The big question for many people undertaking such a task is "what resolution" (or pixel dimensions to use for various mediums). Your article is very informative and explains it in easy to understand terms. Thanks very much.
    John Scriber

  2. Shaey A says:

    Taking photos of clients and I edit with Picasa. I set photos at 8x10... Then I find out they wanted 11x14 and company is saying resolution is too low. Can I fix this?!? Thank you for article

  3. promytius says:

    Resolutions are always rectangular, because pixels are rectangular.

  4. Steve says:

    To say that "resolution is the quality of the image" is not quite accurate.

    There are many technologies within an imaging device that will determine image quality, such as:
    - quality of image sensor
    - level of compression applied
    - type of codec

    All of these impact image quality.

    For example, I have a 12 megapixel Canon 5D and an 18 megapixel Sony cybershot. The Canon captures 30% less resolution, but produces vastly superior image quality.

  5. walking for weight loss says:

    Its such as you learn my thoughts! You appear to grasp a lot approximately this, like you wrote the ebook in it or something. I feel that you simply can do with a few percent to drive the message home a bit, however instead of that, that is magnificent blog. An excellent read. I'll definitely be back.

  6. shivam says:

    Could you please tell what is with the screen resolutions like 600*800 , why don't they use both the same 600*600 or 800*800.

  7. Stephen says:

    Wow great articles David, please keep them coming. I have learned so much from your articles. My wife also reads your articles. Thanks for all the effort. Stephen & Angela

Leave a Comment

Your email address will not be published. Required fields are marked *

10 minutes
About David Peterson
David Peterson is the creator of Digital Photo Secrets, and the Photography Dash and loves teaching photography to fellow photographers all around the world. You can follow him on Twitter at @dphotosecrets or on Google+.