Importing dicom files

Operating system: desktop
Slicer version:4.6.2
Expected behavior:good visualisation
Actual behavior:lack clariy
when i wan to load a dicom directory, when the directory contains dcm files. there is no problem, but when gt a directory where the file are named IM0, IM1, IM2… AND N THE FILES TYPE IT IS WRITTEN ONLY FILE, I AM GETTING A VERY POOR QUALITY IMAGES AN ONLY THE AXIAL VIEW IS SOMEWHAT BETTER.
WHY DOES THIS HAPPEN?

Use latest nightly version of Slicer and the DICOM module to load DICOM images.

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