I found this slim softcover in this Little Free Library in Nashua NH
, while dropping off some books of my own. It's about a boy who becomes apprenticed to a well-known artist, who recognizes his talent - for realistic landscapes, but not for portraits. It isn't that his portraits are bad, just that they're too realistic for then-current tastes - people want to be prettied up before their images go on the wall! And then the boy is summoned to the castle to paint a huge group portrait, while all of the subjects are insisting that he tweak their images as they dictate, under threat of horrible penalties. Poor guy...
The illustrations are lovely in themselves, showing the artists at work, the local scenery, and more - all in the style of the real-life artist on which the boy is based.
As for the story: luckily for the boy, he gets an unexpected respite from all the pressure when the king sees his lovingly accurate portrait of the king's young daughter, and all is well!