This is the question of compression. Choosing compression formats is pretty easy; do you want the original image? Or do you want to be able to upload images to the web quickly and without worry? Lossless is for the people who want to the original, you can’t pick what size the image will end up in but there will be no loss of the original image.

Basically this is for if you want to be able to view the image but not send across the web. Lossy is all about easy transportation of images. You can pick the size of the image and transferring it is extremely easy and fast. Lossy generally ends up in the format of .jpg which is the most commonly read image format across the internet.

Lossless ends up often in the .png format which is the most accepted format amongst average image software.  When it comes down to deciding you have to think about whether you want it to be quickly accessible or completely original.