Using a model sounds wrong, this is image/pixel data, not something shown in an item view.

Since you likely want to show the same image in parallel in both views, using two threads sounds also like more trouble than necessary.

There are likely two approaches

1)
* Worker thread receives the data and created an image
* Creates second image applying the crop region
* Stores both images in variables accessible by the main thread (obviously under protection of a mutex)
* Notifies the main thread via signal of the new images

* Slot on the main thread retrieves the two images and puts them into each QLabel
* Conversion from QImage to QPixmap can take a bit of processing time if the image data formats are not the same, e.g. color depth begin different

2)
* Worker thread receives data and creates an OpenGL texture
* Performs cropping in OpenGL generating a second texture
* Use OpenGL widgets for displaying the two textures

Cheers,
_