How do you complete level 44 on Dooors?

Get the brush on the ground and put it into your inventory.

Select the brush in your inventory, and use it to clean all the white spots on the walls.

You will see that under the spots are animal tracks. Put the picture of the associated animal in each frame.

The left picture should be a human and the right picture a bird.

The door will now open.

See related link for screenshots.