Image Dimensions Viewer Blender add-on
Image Dimensions Viewer is a simple Blender add-on that displays image dimensions right above the image.
In Node Editor you will see image dimensions label above each Image Node. Note that label only appears above Image Node with selected image. If you still don't see the labels, open the Overlays dropdown and make sure the Image Dimensions checkbox is set to True. If you STILL don't see the labels try clicking the checkbox a few more times or relaunching Blender. Follow same instructions for Image Editor label if you don't see it BELOW the image.
Edit -> Preferences -> Add-ons
In the Preferences section, you will find several values to tweak: For Node Editor Overlay:
For Image Editor Overlay: