You don't get to decide whether or not a picture appears on the listing. Google determines that.

Hillary knows more than she thinks she does!! ;-)

The original development of the ALT tag was in case an image didn't "render" the way it should (which happened a LOT in the old days) a set of words would appear in place of the image.

Nowadays, these images are searchable when you go to Google Search and switch from Web to Images. All the images related to your keywords come up via the ALT tag (and some other related information) So, this is indeed one way to do it. ALT tag those images with your keywords - the first one is most important, use LSI keywords (secondary keywords) and variations of your keywords if you have multiple images in the same post.

As your page gets indexed in the "web" search, your images also get indexed within the "image" search function. It will, of course, take some time.

Hi Diem,
I don't know the answer to that one. I hope you get the answer soon. Have a good evening.

Sorry I can't help, but I am very interested to hear the answer, many thanks for raising it :)

from my understanding, you need to use the alt tag to make sure you name your photos the same as your keyword. then they will show up in search engine results for that keyword.