When you want to train your neural network, you have to:
- Preprocess your data images, in order to "clean" your dataset
- Decide which features you want to extract (this is a very difficult task, because you have to decide which features are relevant for recognition and which are not. This passage is already done in Iris dataset)
- Proceed to training and testing your neural network
So, if you look at number two, you can see that Iris dataset it's not an image dataset. However it has a number of features that you can use to train your neural network.
So the question is:
Which features do you want to extract from your images in order to train your neural network?
If the answer is: the features already extracted in the Iris dataset (number of sepals, sepal width, etc.), then you can proceed to train your neural network.
If the answer is: I want to extract features directly on images, then you have to study this step.