JPG (.jpg) is generally the best format for sending photographs. PNG (.png ) is better for sending graphics with a relatively few colours.
Bear in mind that JPG is only a file format and jpg files can be output all the way from no compression right through to extremely compressed.
If you’re starting with an image directly from a camera, setting the compression between 60% and 80% should retain a good level of image detail while maintaining an acceptable file size.
Do not submit raw images
Bitmap files (.BMP) and Tiff files (.TIF or .TIFF) are raw files, i.e. very large files which contain every last pixel of data captured when a photograph was taken. They’re great for printing but the filesize is way too large for sending over the web. Raw files can be upwards of 20MB each, whereas a file for the web should be less than 1MB.
File size is important
Raw images direct from your camera are great for printing but they’re overkill for reviewing on a screen. Tutors receive a lot of files and they have to download them all, so the less time it takes, the better. Reducing your images will also help your images files getting corrupted or timing-out when you’re submitting your work.