Reverse Impression?

That is embossing, which usually involves a “die” which presses material into the recesses in a “counter-die”.

Example of die and counter-die:
http://www.datagraphicdesign.com/wp-content/uploads/2011/10/embossing-1....

Embossing. the die has the recesses the counter presses the stock into it to raise the image. Counters can be premade by the engraver or made on press.

Oops, thanks for the correction! (gets more coffee).

It can be done with photopolymer plates as both die and counter. Gene Becker used to have a brief tutorial on the website but it was gone the last time I looked.

The example you have posted (orumco) is produced using a sculpted die, which has multiple levels. You could get somewhat similar results with a flat embossing die, but it would lack the detail of the crease in the middle of the raised portion. The amount of embossing shown also most likely was done using heat to help stretch the fibers of the stock to fit into the die without cracking. Using heat you can get deeper embossing effects, and sharper definition of the embossed image.

Otherwise everyone is correct in what they have commented on flat embossing done with a reverse engraving and pre-made or made-on-the-press counter die.

John Henry