How to plot a graph (Area vs. Distance) when doing image processing of an image?

I would like to add to my program a graph Area (y-axis) vs distance (x-axis). My program is to process images. For example, I have an image taken at distance 2 m and after processing it, I found the area to be 200 m2. Another image at distance 3m, the area is 400 m2. I want to first ask the user that the image he is entering is at what distance and then process those images to get the area respectively. I want the program to the distance of each image and the processed area. Later, I want to get the area under the curve to get the volume from the plotted graph.