Matisse Nude Among The Waves Print

It is a poster size. No visible signatures. Should I take it out of the frame to check for publisher/printer text or it would not matter as it is most likely an offset print rather than a linocut?
Had to edit the photo because of the reflections on the glass. It is pitch black ground with white images.

 

Well...it isn't blue...

 

Mattise did make linocuts on black ground.

 

I guess I will take it out because I can't tell what kind of print that it with the glass one.
The visible size of the paper is about 22" x 34".


I see the original is from 1938 but can't find anything about sizes, editions etc.

 

Finally found some time to take it out of the frame. Nothing new. The mat is glued ( who would do that ?) so I can't check the edges for text. It's on glossy paper laid over paper board. Still no idea what kind of print, offset litho, glicee ...
Interesting why there are no other reproduction that I can find online.