さんによって 2021 年 9 月 17 日 に MATLAB Answers では不適切 としてフラグが設定されました。
It's not clear how this is related to MATLAB. Asking for help implementing an image processing algorithm is IMO appropriate for Answers; asking for the algorithm itself seems better suited for a different forum.
In this image can anyone tell me how to find out if a mushroom is diseased?
I suggest you try deep learning. Input dozens or hundreds of images you say are healthy and an approximately equal number that are diseased. Train the deep learning model to classify it. It will figure out what it needs and give you the answer.