|Lamentation by Petrus Christus, via Wiki commons, click on the picture to view it larger|
This example of using so much blue is rather unusual for Petrus Christus himself. He most often used red for Virgin Mary's robes, as was common in the Northern painting. Blue was more common in France. This is of course rough division, the geography, but this is a more factual explanation to clarify this red and blue vision, than color coding Virgin Mary and Magdalene rigidly.
Rather dogmatic is thinking in red and blue, which sometimes happens today, as art historians and art history buffs say. This means the idiosyncratic idea that Mary the mother of Jesus was depicted only in blue robes, and Mary Magdalene was depicted only in red robes. Luckily the Old Masters where not as limited, or as color blind.But some art historians complain that it is difficult for some people to understand this fact, and even those people will rather aggressively defend their pet idea, in spite the fact that their knowledge is limited.Why is it, and why some people are so fiercely attached to this specific color combination, is a mystery for me. As one art historian said, the subject of the robes of those two venerated quickly reveals how much someone knows, or rather how much someone doesn't knows about art history.
Art historians are not as ignorant as they often gladly represented as: most important, they see a lot of art; when I took history of art on the exam we had c. 600 slides,which were part of the test in the introductory course only, later things were more complicated. Art history classes were compulsory for my degree. I had strong interest in art history quite early, started when I was 13 year sold, so I didn't struggle, but for those people in general who learn art history as elective, mostly it it not an easy A class. It depends on university and who teaches the class, but in general challenges are there, if you want an A, better work hard, as it is not hobby level art history.
Art historians are very involved in general: they travel if needed, study artists' historical contracts by the patrons and artists, write books, keep current with current research. So, why this need to tell art historians they are so wrong, and specially by people whose knowledge belongs to the limitations of a hobby? Mystery, mystery...