Thanks for this, just a minor thing:
You have price per hour and performance per second. Thus that ratio is not performance per image per $, you need to scale that. Also, the metric is not "images per second per $", but just "images per $".
You have price per hour and performance per second. Thus that ratio is not performance per image per $, you need to scale that. Also, the metric is not "images per second per $", but just "images per $".