Isolate all images from a pdf document

[DPaul]

For example the following image is a single image, it was created with the linux command

Sure, an image is a (jpg,png,tif...)-file with x_pixels / y_pixels, and what is on it, can be anything.
My question is:
a) Paste this picture in eg. MS Word, and "save as" pdf -> I assume the pdfReader can isolate it. (as one pic)
b) Print this image on a white page, scan the page as pdf -> I assume the pdfReader cannot see the picture.
Am I correct ? Or is pdfReader equipped with some magical algirithms.

thx,
Paul