Challenge: The Mysterious Painting

Difficulty: Hard (3/4.4)
Social skills: None required
Motor skills: None required
Detective skills: Very good skills needed; may require coding and/or third party tools
Prize: A packet of Bird’s Instant Custard (Smooth and Creamy!) + £5
Closes: A few days after the first correct entry
Eligible: All members and alumni of ECS (except Helpdesk)

Peter’s hand trembled slightly as he slid the tiny memory card into the reader. He paused to swallow another long draught of whisky to steady his nerves and then fired up Nautilus to browse the card’s contents. On the screen before him he saw two files. His lips drew into a faint smile as he recognised the first – a MIDI file of Gorda Stara Planina.

“For all his faults, Kolyo was a patriot to his dying breath,” he mused, “and never without a sense of humour.”

The second was an image file, a JPEG. He double-clicked on it and the picture popped up in the centre of his screen. A painting.

Peter stared at the image blankly. What did it mean? He knew for certain that Nikolay was trying to tell him something of the utmost importance. The old man had died making sure the memory card reached him. But what was it?

Q: Here is the painting. What was the message? (Update: check out the next clue)