When you post photos online, you don't need nearly as many pixels as you do when printing. This trend also applies to images that will only be viewed on screen, such as in a slide show or presentation.
How to Share Your Family Photos | Sharing Your Digital Photos
When you post your photos on the web or send them via email, the smaller you can make them the better, to make the most efficient use of bandwidth and storage space. There are three things you can do to make your photos smaller for sharing online:
Since pixels per inch and dots per inch are only relevant to print size and quality, you only need to consider pixel dimensions for digital photos for the web. Most 24-inch desktop monitors today offer a resolution of 1920 by 1080 pixels, so your images do not need to be any larger than this for on-screen viewing. Laptops and older computers have even lower screen resolutions, so keep that in mind as well. The smaller the pixel dimensions of an image, the smaller the file size will be.
File compression is another way to make your photos smaller for online use. Most cameras and scanners save in the JPEG format, which uses file compression to keep the file size small. It is a standard file format that any computer can read. JPEG compression can be applied at different levels, with image quality and file size having an inverse relationship. The higher the compression, the smaller the file and the less quality it will have.
