Russian Stamp Sc#56 Groundwork Inverted?

I think that my stamp is Sc#56
It is the best I can with my mobil phone:





I made another with my minimicroscope Bresser (the groundwork and the open "b" russiam charactere)




What you think?
It is a groundwork inverted?
The open russian "b" it is a vatiety?

The stamp is from 1902-04 vertically laid paper.No inverted background but it has a slightly shifted background towards the right.Not enough shift to make it worth more.Common occurrence in this stamp.The b break could be a cliché variety,but not certain.
.

Thanks for the answer, perf12

I checked the stamp again and noticed that the background image had to be rotated 180 (in the minimicroscope objective the image is rotated)
Can you explain the groundwork recognition methodology?
Thanks.

This is the correct image

Thank you rod222
The background look inverted.The question is: "it's applicabily to my type stamp"? In your image I saw the different design stamp and value 4 and 10k.

It's correct?

Cupram,
I do not have a Russian special catalogue, to answer your question.
Others shall need to respond.

I hope so
Thank for your aid rod222

In the stamps with the crown above;inverted background means there is a ghost or blank spot at the bottom where the crown should be placed.The stamps were printed in two steps and in the case of colored centers 3 steps.First the background then the center (crown letters and shield).Below a 1902 stamp (same serie as yours) with inverted background:



____________________________________________________________________________
The inverted backgrounds everyone mistakes for.These are inverted and have no ghost
white areas because the design is symmetrical.The famous 4K & the more common 10Kbelow:

So, each of these two different designs can exist with inverted background. But the method for detecting the inversion is not the same in each. For the design that cupram submitted, the crown is supposed to be printed on a space in the background that has been left blank for it. If that blank space appears at the bottom of the stamp, the background has been inverted. So cupram's stamp is not inverted background.

The explanation that Rod222 provides is for the other stamp design (the one without a large crown), where the location of dots in the rhombus shapes of the background is determinative.

Thank you very much ,perf12.
Very good explanation and logic in the same time.

Yes, thanks for clarification.
I did have the information, recall failure
https://goscf.com/t/12645&whichpage=2#115487