Can I use one big picture to fill instead of a gradient fill? Also conditional formatting

Hi all,

I am currently working on a project and want to use a picture of a cauldron and have that filled in as opposed to a bar graph filled with cauldron pictures. Is this possible? I picture something similar to how someone would fill a picture on a piece of paper until they hit their goal.

Secondly, If I need to do a bar graph I know I can do conditional formatting on the values within their cells but can I create this formatting specifically to the graphs themselves?