import sqlite3

data = open('test.clip', 'rb').read()
sqlite_head = data.index(b'SQLite format 3')
with open('test.sqlite3', 'wb') as dbf:
    dbf.write(data[sqlite_head:])
sqlite = sqlite3.connect('test.sqlite3')
image_data = sqlite.execute('select ImageData from CanvasPreview').fetchone()[0]
with open('test.png', 'wb') as imf:
    imf.write(image_data)