You can easily prevent Google from indexing your pictures by doing below steps.
1.Login to your blogger dashboard--> layout- -> Edit HTML
2.Scroll down to where you see <head> tag .
3.Copy below code and paste it just after the <head> tag .
Best royalty free stock photos, illustrations and vector images at Depositphotos.com.
<meta content='noimageindex' name='robots'/>4.Now save your template and you are done.