r/MachineLearning - [D] GUI tools for data manipulation for machine learning?

I am aware of several awesome Python libraries that allow me to do image manipulation, cropping, etc. to prepare my data for training input to Neural Nets. Are you aware of nice looking tools with a graphical interface specifically for the purpose of data preprocessing (resize, crop, brightness) and manipulation (say, assign classes to multiple images easily)? I know every problem is unique and everybody has its own setup, but are there tools out there that do this well?