Photos for the Web
Digital images are measured in pixels, where printed images are measured in inches. The concept of dots per inch (dpi) is a print concept. Although standard practice on the web is to set document resolution to 72 dpi, photo dimensions in pixels are what determines screen appearance and image size. When preparing digital images, keep in mind these tips.
- Optimize photos to reduce the file size.
- Crop and resize photos before inserting them on a web page. Don't scale down the width and height of a larger photo to make it fit on a web page. You will reduce the visual size but not the bandwidth of the larger image, which will result in slow-loading images on your web page.
- Increasing an image more than its original size will make it appear grainy on the web.
- Because jpgs have lossy* compression, they should be resized from the original.
Don't use someone else's photos unless you have permission. Then as a courtesy, make sure to credit the photographer.
*lossy: compression formats that suffer from generation loss, where repeatedly compressing and decompressing the file will cause it to progressively lose quality