Read & Rhyme (Atari ST) python image file dumper

rrdump.py

#!/usr/bin/env python3

#
# Python script for dumping images from Read & Rhyme (Atari ST)
# Brad Smith, 2019
# http://rainwarrior.ca
#
# Format is very simple:
#    1 x WORD header? always 0.
#   16 x WORD palette
#  320 x 200 image packed in 4-plane WORDs (standard Atari ST image)
#

import os
import struct
import PIL.Image

def find_files(ext):
    ext = ext.lower()
    fo = []
    for dirpath, dirnames, filenames in os.walk("."):
        for fn in filenames:
            if fn.lower().endswith(ext):
                fo.append(fn)
    return fo

def dump_pal(filename,verbose=False):
    d = open(filename,"rb").read()
    head = struct.unpack(">H",d[0:2])[0] # always zero?
    if verbose:
        print("Head: %04X" % head)
    pal = []
    for i in range(0,16):
        p = struct.unpack(">H",d[2+(i*2):4+(i*2)])[0]
        r = ((p >> 8) & 7) << 5
        g = ((p >> 4) & 7) << 5
        b = ((p >> 0) & 7) << 5
        pal.append(r)
        pal.append(g)
        pal.append(b)
        if verbose:
            print("Palette %2d: %04X (%3d,%3d,%3d)" % (i,p,r,g,b))
    return pal

def dump_rhy(filename,overrides={}):
    print("Dumping: " + filename)
    d = open(filename,"rb").read()
    pal = dump_pal(filename,True)
    if filename in overrides:
        override = overrides[filename]
        print("Palette override: " + override)
        pal = dump_pal(override,False)
    img = PIL.Image.new("P",(320,200))
    img.putpalette(pal)
    for y in range(0,200):
        for x in range(0,320,16):
            pos = 34 + (y * 8 * 320 // 16) + (x * 8 // 16)
            p = struct.unpack(">HHHH",d[pos:pos+8])
            for s in  range(0,16):
                p0 = (p[0] >> (15 - s)) & 1
                p1 = (p[1] >> (15 - s)) & 1
                p2 = (p[2] >> (15 - s)) & 1
                p3 = (p[3] >> (15 - s)) & 1
                img.putpixel((x+s,y),p0|(p1<<1)|(p2<<2)|(p3<<3))
    fileout = filename+".PNG"
    print("Saving: " + fileout)
    img.save(fileout)
    print()

# these two don't have any palette data
overrides = {
    "RHYMEOVL.RHY":"RHYMEPIC.RHY",
    "ROCKETS.RHY":"ROCKPIC.RHY",
    }

for f in find_files(".RHY"):
    dump_rhy(f,overrides)