The Google Accelerated Science team has published an ImageJ plugin, Microscope Focus Quality, for assessing the focus quality of microscope images using a pretrained TensorFlow model.
The Microscope Focus Quality plugin classifies image tiles into 11 classes (hue) with varying confidence (brightness).
For details, see the Google Research Blog post Using Deep Learning to Facilitate Scientific Image Analysis, as well as the publication in BMC Bioinformatics:
