How to calculate recall for image detection model based on image segementation?

I created a model based on mage segementation to detect cracks and i used jacard index to determine TP, FP, FN

I know that recall =TP/(TP+FN)

Assume I have 4 images i got 3 of them TP, Iou>0.5 for the three images and fourth one is FN , what I know I have to calculate accumulative TP and accumulative FP

thus the precision for first image =1

second image 2/2=1

third image 3/3=1

fourth image the precison=3/3=1

what about the Recall?some said the dominator will be total number of labeled images so if I have 4 images of crack as example the dominator always equal 4 but if I have one image FN from 4 images?

what i said is mentioned in Metrics on Object Detection. In this blog we will look into… | by gandham vignesh babu | Medium they applied accumalative in TP and FP , shall i applied accumalative FN too to calculate recall or direct the dominator of recall is the total number of images

Remember my condition is binary classification crack or not based on image segmentation

Answer 1

[Image Analyst]

See discussion in your duplicate post: https://www.mathworks.com/matlabcentral/answers/2049337-how-to-calculate-the-precision-and-recall-determine-fp-and-fn-for-image-detection-based-on-image#comment_2970477