What size should my image be?Posted: July 3, 2012
One question I get asked a lot by colleagues and students is how big should their image be?
There are two related sides to this question – the first is resolution and the second is actual size. I will discuss resolution in more detail in later posts but as a rule of thumb you should have a resolution of at least 300dpi for print or publication. If the image will only ever be used in a presentation you can (and should) take the resolution down to 75dpi.
With regard to the actual size – it depends on the destination of the image. Ask yourself the following questions:
- Is the image for a publication? In this case, look at the dimensions of the journal in question. Do you want your image to fill a whole page or just one column? You may not have the final say in the positioning of images in your paper but you can plan whether to create wide or narrow images to help with an appealing layout.
- Is the image for printing in a thesis or dissertation? In this case you will likely have your image on a page of its own with a caption. I suggest you make the image approximately half the size of the whole page. If you will be printing on A4 paper, making your image A5 size (148mm x 210mm) is a good start. An A5 page, in portrait orientation, fits beautifully on an A4 portrait page leaving plenty of room for margins, binding and a caption. Much bigger and your page will look crowded, much smaller and your image will look insignificant in the middle of all that white space.
- Is your image for a presentation? Take a look at your slide layout – do you want the image to fill the page or just a portion of it? Set the appropriate dimensions before you start creating your image.
The other thing to take into consideration is the dimensions of your original data image (if you are compiling a montage like the one shown here). You will need to think about how many rows and columns you need, whether you need room for labels, and whether the images are to be used as is or cropped.
Whatever you decide to do it is always worth thinking about these things before starting to put together your figure – it is much easier than changing things around later.
Have you discovered any useful rules of thumb for sizing images?