The difference between image size and image resolution

The difference between image size and image resolution

 

One of the most frequently asked questions from our clients is about image size or should that be image resolution? It can be confusing and one depends on the other, so we’re going to take a look at why these two terms often get confused and what they mean.

All about pixels

 Both image size and image resolution refer to how an image is measured. When you capture a digital image, via a digital camera, your phone or a scanner, it’s measured in pixels – which is an abbreviation of means ‘picture element’ and it is the smallest unit of a digital image. Pixels are also measured in terms of DPI (dots per inch) or PPI (pixels per inch)  and it is this measurement that affects resolution. The more DPI or PPI, the higher the image resolution. Because pixels are tiny, we often hear about Mega Pixels, particularly when it comes to cameras and photography.

A key selling point of digital cameras is the number of pixels a camera can capture. For example, a 16 Mega Pixel camera is capable of recording images with an image size of 4920 pixels wide x 3264 pixels high. But, one of the key rules in photography basics is: ‘Just because you can capture an image with 16 Megapixels doesn’t mean you need to’. It all depends on the size of the image that you need, which depends on what you’re going to use the image for.

You could be saving money too. If you’re using stock photography, the prices vary depending on the size and resolution of image you need. Understanding the relationship between image resolution and image size will save you making expensive mistakes.

What’s the end game?

When it comes to resolution requirements, what really matters is the end product. What are you using the image for?

  • Are you printing a poster?
  • An A4-sized photo?
  • Brochure or flyer?
  • Print advertisement?
  • Social media post?
  • Web design?

The risk with choosing the incorrect image resolution is that your photo or image will appear ‘pixelated’ or grainy, blurry and unfocussed. This happens when you are trying to use an image where the resolution is too low. There are also risks associated with choosing an image resolution that is too high. Digital images that have a very high resolution take up a lot of storage space, just ask someone with a 16MP camera. Large image files are slower to load, which is a major factor in website design.

The table below is a big help when it comes to checking if you have the correct relationship between image size and resolution.

Photo Enlargement Chart

File Size
(Pixels)
MegapixelsMaximum Print Size
@200 DPI
Maximum Print
Size @300 DPI

1,600 x 1,200

2MP

8.0 X 6.0

5.3 X 4.0

2,048 x 1536

3MP

10.2 X  7.6  

6.8 X 5.1

2,592 x 1944

5MP

12.9 X 9.7

8.6 X 6.4

3,072 x 2304

7MP

15.3 X 11.5

10.2 X 7.6

3,264 x 2,448

8MP

16.3 X 12.2

10.8 X 8.1

3,648 x 2,736

10MP

18.2 X 13.6

12.1 X 9.1

4,000 x 3,000

12MP

20.0 X 15.0

13.3 X 10

4,288 x 3,216

14MP

21.4 X 16.8

14.2 X 10.7

More information?

We’re living in an image-saturated culture, yet a surprising number of businesses are still unsure about which images to use and how they should use them. At iFactory, we help a wide range of businesses achieve their marketing goals by creating award-winning websites, digital strategies and best practice brand integration.

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