Create precision/recall with TP FP FN

Hello,

I want to create a graph showing total of True positives False Negatives and False Positive results. Im doing a project where i detect smoke regions from images and seperate these from fog objekts. I test 40 images, 20 contain smoke and 20 contain fog. The fallowing results show:

For smoke images:

18 TP

2 FN

0 FP

For fog images:

0 TP

0 FN

4 FP

How can i create this graph with precision/recall? or is there a better way to visulize this ?

thanks for all the help in adnvace!