Technical reasons for not having large background images in websites

Question

Most websites tend to have either a solid color as background, or a small image that is repeated. Why aren't more websites using a large image (such as a photo) as background? I can think of the following reasons:

1) Problems with different screen resolutions. Too small and gaps start to appear on the left and/or right side for higher resolutions, too big and lower resolutions only show part of the image.

2) Bandwidth. Although this is unlikely to be a problem for most websites.

Are there any other reasons why such backgrounds are not being used more often?

Answer 1

I think that images as background have a tendency of making the text difficult to read.. :)

Answer 2

Background is not part of the content of your website, it's here to make it more clear.

Pictures are part of the content, and the complexity make the text harder to read.

Answer 3

You've pretty much identified the two main reasons, but the most important one is bandwidth. Depending on the type of image, you'd be best to consider all those users in your target audience whose technical limitations mean that sitting and waiting on a dial-up connection (they're still out there, you know) will alienate them.

In addition to the time and resource cost of sending large images down the pipe to your users, the usability issues of forcing the user to wait for the image to load and the impact of readability of content mean that background images should best be limited to tileable, scalable or small UI enhancements rather than full UI features.

Answer 4

I think that the main problem is about resolution, but with CSS3 we will forget thanks to the new property Background-size

Answer 5

Your assumption about bandwidth not being a problem is unfounded. This is an illustration of global broadband availability (source):

And that's not including cell phones, which are probably the fastest growing group of devices used to connect to the Internet. Finally, the fact that you took the ergonomic aspects out of the discussion (narrowing it to technical aspects) makes it more of an "academic" discussion as you've excluded the main reasons not to use large background images (i.e. readability).