Below is a list of acceptable file formats for web graphics andphotos to help you achieve the best results visually as well asreducing file size for your online community.

.jpg

JPEGs are designed to efficiently compresscontinuous colour or grayscale images, such as photographs or fineartwork. JPEGs do not work well on hard-edged images with areas offlat colour, these are better suited to GIFs or PNGs.

.gif and .png

GIFs and PNGs are used for flat-color images like logos,buttons, and graphic text, and are based on the number of colorscontained in the image. Finding the least number of colours withoutcompromising the quality of the image will yield the best resultsfor keeping your file size down for the web.

When it comes to compressing files for web PNGs tend tocompresses better than GIFs (in most cases). However, InternetExplorer 6 does not support PNG graphics while Internet Explorer 7,Mozilla Firefox, and most modern browsers do.

Use PNG files for creating transparent backgrounds that arecontinuous (uses alpha channels), not flat - for example if youhave a logo with a large drop shadow that you want to blend gentlyinto a background. GIFs also support transparencies however arebetter suited for flat transparency use, either a pixel exists orit doesn’t - for example, a button that has straight solidedges.

.bmp

BMP files format, sometimes called bitmap, is usedas the standard storage format in the Microsoft Windowsenvironment. Although it is based on Windows internal bitmap datastructures, it is supported by many non-Windows and non-PCapplications.