// start picker to get image for cropping and then use the image in cropping activity
CropImage.activity()
  .setGuidelines(CropImageView.Guidelines.ON)
  .start(this);

// start cropping activity for pre-acquired image saved on the device
CropImage.activity(imageUri)
 .start(this);

// for fragment (DO NOT use `getActivity()`)
CropImage.activity()
  .start(getContext(), this);