https://ieee-dataport.org/documents/coal-and-gangue-infrared-images . These data are infrared images of coal and gangue in BMP format. You can use them to train and test your classifier such as SVM, CNN, etc.

These data are licensed under a Creative Commons Attribution 4.0 License.

You can use variety of datasets on Kaggle. You can even view the codes written by other people on the dataset that you need.

https://www.kaggle.com/datasets

One of the most simple image datasets for training deep networks is MNIST: https://www.kaggle.com/datasets/hojjatk/mnist-dataset

Please note that many deep learning libraries have interfaces for this dataset, for example in PyTorch you can use: https://pytorch.org/vision/main/generated/torchvision.datasets.MNIST.html