Segmentation of leaf with different views in images for classification

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Hello guys, for leaves of a plant, I have different images. The distances that the images are taken are different. Also, I have different views of the leaves. Now I have to do a pre-processing and then classification. For the classification part, I know what to do for classification. Unfortunately I have not found any suitable method for pre-processing part and segmentation. I have done various segmentation methods too. Due to the situation and condition of leaves in images, what should I do? What are the steps to reach the goal?

C:\fakepath\10.jpg C:\fakepath\11.jpg C:\fakepath\12.jpg Thanks.