You want all your product images to be indexed by google images? ensure they all appear on indexed pages, have suitable alt text and Google should do the rest.
Here are the three things you need to do to show up your website product images on Google: image filename alt tag supporting text
Having images that take a long time to load, will affect your whole website ranking. Ideally they should load within 1 second. Having unique images that nobody else has will increase their chances of being shown in Google images.