Possible: graphic opacity(alpha) ?

I want to do some sheets educationnal stuff for children with graphics: I tried to find how modify the opacity (alpha) of graphics in Dorico without to do it in other external program before to import it in Dorico. Is it possible?
Best regards

Export graphics as Color, not Mono.

My english is not very good , so perhaps I badly expressed.
When I put graphics on a page I want to change their opacity
You tell me about option we find in the print page… don’t really undestand??
Best regards

You cannot change the opacity of graphics in Dorico, but Dorico will respect the alpha value of any imported graphics, so you will have to edit them in an external application before you import them into graphics frames in Dorico.

Thanks Daniel for your answer but:
That’s what I did till now but need often a lot of test to find the right ratio of alpha that works!(How many test did you do, to fixed the ratio in the watermark option in the print page?)

The possiblity to change the z-index (bring to front, send to back,send Backward…) could be great. Dorico choosed the option to allways put the graphics over everything but often in publication with images (children publication), it’s the opposite: the picture or graphic are under the music so we can still see the lines and notes at 100% black without disturb reading a lot the music (like Dorico did in the print option with the watermark: the watermark is underlay of the music)
Here is examples of a php script (fpdf and fpdi) to see and understand this kind of nuance.
Best regards