Image pre-processing techniques (Justification required)

In below picture author use 8 preprocessing techniques Follwo A-H .

Can anyone Please provide justification why he use 8 preprocessing techniques with CNN.Authors use CNN for finger vein recognition.

CNN is a robust technique in which minimal preprocessing is required such as cropping and resizing even though the input images are low quality. You can refer this statement in Radzi, Syafeeza Ahmad, MOHAMED KHALIL HANI, and Rabia Bakhteri. "Finger-vein biometric identification using convolutional neural network." Turkish Journal of Electrical Engineering & Computer Sciences 24, no. 3 (2016): 1863-1878.DOI:10.3906/elk-1311-43

Refrence paper is attached below

Answer 1

[Image Analyst]

I imagine he preprocessed the images to try to improve the images before the CNN step. If you start with better images then you should be able to get better results.

[Anas Bilal]

Can you please elaborate it in detail.In the other paper they jsut use 2 preprocessing steps and then apply cnn on their own dataset consist of 50 images only.But in the given figure they use 4 different dataset with around 4000 images.

[Image Analyst]

Sorry, no - I didn't read the paper, nor do I have time to. What did the authors say when you contacted them?