You submitted this question a few weeks ago and without a workbook example, it's hard to do more than refer you to anything other than some examples. I like this one - Endangered Safari | Tableau Public
but check out Tableau Public's gallery for examples of what you are trying to do as a great resource to get going.
Thanks for your response. Before posting the question I had seen this dashboard in tableau public but I was not sure if I knew a way to make the size of the image proportional to the metric value.It seems the question was not very clear and I could have phrased it in a better way.
Would you know if we can make image size proportional to the metric value?
Try placing the measure/metric on the size shelf - that should make it do what you like. A sample workbook with a few images to attached in a .twbx would be helpful to assist if you get stuck.