Despite the Princess of Wales -- or someone at the palace -- having sketchy photo editing skills, Photoshop's parent company, Adobe, saw a spike in its stock price after Monday's trading ... affirming the old adage of any publicity's good publicity.

Here's the breakdown ... Adobe (ADBE) went from $551.69 on Friday, did a little Monday morning stretch to $552.45, and by the end of the day, they were ridin' high at $560.42. The numbers don't lie!

Business writer Trung Phan immediately put the company's $3B market cap to Princess Kate's claim she'd used Adobe's product.

Of course, it's unclear if the Kate saga really is behind the fluctuation -- but the whole thing is a bit of a coincidence.

It also seems like everyone's getting a kick out of imagining Kate as just another regular Joe, clicking away on Photoshop like the rest of us mere mortals.

One person joked on X, "I like the idea that kate middleton got a royal discount on adobe creative cloud and started poking around in Photoshop," ... and another added, "The Palace now upgrading to the full Adobe suite to fix the Kate Middleton pic."

Nonetheless, while a whole set of conspiracy theories are floating about why the royals doctored the pic ... KM's official Kensington Palace statement claims she just did a crappy job using Photoshop to improve her Mother's Day snap with her 3 kiddos.

Her apparent falling on the sword doesn't explain why the Palace lied, in the first place, about when the photo was taken -- nor does it shed any light on what's really going on with Kate's now 2-month-long recovery from abdominal surgery.