The best, most economic for sending via e-mail: Probably .GIF and .JPG but read on.
.TIF are regarded as best to preserve the picture quality but not as economical.
When your are looking at the most economic way to send files over e-mail you should consider the following formats. For example, a picture in .BMP format (I tested to get the dinkum info) with a file size of 726K, if saved in another format will reduce to file size as follows,
.BMP = 726K
.TIF = 386K
.GIF = 124K
.JPG = 64K
Similarly a .BMP of 82K…………
.BMP = 82K
.WMF = 83K
.TIF = 51K
.GIF = 47K
.JPG = 23K
However, for the really high quality option for those who MUST have the best quality (like a special photo to keep maybe) the original file format is always best as each time it is changed it can lose a little quality AND those formats which compress such as .JPG and some others will degrade a little (if you’re fussy).
Note: Most modern graphic software will allow you to load in one format and save in another. Ones like ‘Paint’ which comes with Windows doesn’t have many save options even though it might load them OK it will only save as a .BMP (Bit Mapped Picture).
ANIMATED .GIF FILES:
As you will/have find/found out, some picture files are (can be) animated. This is actually done exactly the same as a Disney cartoon, frame by frame…. lot’s of fun. Each frame is slightly different, or just two frames which alternate maybe. The individual pictures are combined (via special software) into a single picture which of course has to be larger than each of the single pictures….. In fact an animated .GIF using say 14 single files each of 2K combines to make an animated .GIF of 17K ( 14 x 2K = 28K) so it’s not the actual total of all pictures, just keeps track of the changes between them.
The animated signature,[Index] & [Print] buttons are also animated .GIFs I have made.