World assets rendered incorrectly (treasure room: pouch, background after picking up diamond)

[harrytyp]

Description

Some world assets are rendered incorrectly. Two observations in the treasure hold (room 9):

1. The pouch is drawn incorrectly — wrong position and/or rendering artifacts compared to the 8-bit original.

2. After picking up the diamond behind the pouch, the background behind the diamond renders incorrectly — the area where the diamond was does not return to the correct background (stale diamond pixels remain / background artifact).

Suspected directions

• HD background "layer" files that pre-composite world objects into the background (the diamond may be baked into the HD background, so removing the in-game object leaves its pixels behind)
• The Step 2 clean-background diff not updating after an object is removed from the room

Environment

• comiupscale ScummVM fork, HD mode 4x (2560x1920)
• Room 9 (cannon treasure hold), first playable area