If you design for magazines or books you use digital images. You need images with the right resolution. Digital images are made up of millions of coloured dots and resolution is measured in the number of dots per inch (dpi). When they are printed images must have at least 300 dots for every inch on the page. They can look fuzzy if they are not high enough resolution.
Here is a photograph of the garden of Plas Brondanw near Porthmadog. The first copy is 3,264 pixels wide by 1,840 pixels high. The second copy is 698 by 393 pixels. When you look closely you can see the detail is fuzzy or ‘pixelated’. For example, the railings look strange.
If you wanted to print this picture in a magazine you would need at least 300 dots for every inch of the size in the magazine. 3,264 pixels could be printed up to 3,264 divided by 300 = 10.88 inches wide. 698 pixels could only be printed up to 698 divided by 300 = 2.33 inches wide.
If you had the 698 dpi image but you wanted to crop it and show just the building, what would happen? The cropped picture would be about 300 pixels wide, so it could only be printed 1 inch wide.
Task
You will need some magazines and a computer with saved images to look at.
Look at some images on your computer to decide how you could use them in a magazine.
- In your folder, look up the file information for each picture.
- Note down the dimensions, which will say something like ‘3264 x 1840’ or ‘698 x 393’.
- To work out how big you could print them, divide the dimensions by 300.
- Look at a magazine and imagine how you would use one of your pictures in it.
- Measure the width you would like it to appear in inches and multiply it by 300 to get the dimensions you need.
- Does the image you chose have enough resolution?
- Imagine you want to crop your image. If you want to use half the width of the image you will only have half the dots. Is your image still big enough?