Web Safe Images
Posted in Tips For The Web, Web Browsers on February 10th, 2009 by JoeFor the most part you won’t give file formats or colour modes a second thought unless you’re a graphic designer, but there are a couple of things to bear in mind when saving images for the web:
File Formats
- GIF - 8-bit pallette, so limited to 256 colours including “transparent”. Lossless compression. Can be animated. Useful for small icons.
- JPG - 24-bit pallette (full colour). Lossy compression can mean poor image quality if set too high but good filesizes as a result. Useful for photographs.
- PNG - 24-bit pallette including alpha-channel transparency which enables any percentage transparency on any pixel regardless of colour supported by all modern browsers. Lossless compression. Ideal for more complex icons or images with crisp edges. The only downside is a relatively large filesize.
Colour Modes
It’s important to remember that images for the web should be saved in the RGB colour mode. Some image editing software (particularly on Apple Macs) will automatically save images using the CMYK colour mode. Internet Explorer 7 and Google Chrome will not display images saved in CMYK, instead putting in an image not found placeholder. Firefox, Safari and Opera are able to decode these images and display them correctly. RGB for web, CMYK for print.