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Parametrize the RGB palette to encode with, and support both NTSC and

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IIGS palettes.

Move the palette diff_matrix generation into make_data_tables.py since
that is the only place it is used.

Demand-load the edit distance matrices when transcoding.
This commit is contained in:
kris
2019-06-15 21:02:00 +01:00
parent 824154fd39
commit ca817999f6
11 changed files with 237 additions and 157 deletions
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165
transcoder/make_data_tables.py
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@@ -1,11 +1,16 @@
import bz2
import functools
import pickle
from typing import Iterable
from typing import Dict, List, Iterable, Type
import colormath.color_conversions
import colormath.color_diff
import colormath.color_objects
import numpy as np
import weighted_levenshtein
import colours
import palette
# The DHGR display encodes 7 pixels across interleaved 4-byte sequences
@@ -65,7 +70,6 @@ import palette
# contiguously into an array whose index is the (source, target) pair and
# the value is the edit distance.
PIXEL_CHARS = "0123456789ABCDEF"
@@ -74,14 +78,14 @@ def pixel_char(i: int) -> str:
@functools.lru_cache(None)
def pixel_string(pixels: Iterable[palette.DHGRColours]) -> str:
def pixel_string(pixels: Iterable[colours.DHGRColours]) -> str:
return "".join(pixel_char(p.value) for p in pixels)
@functools.lru_cache(None)
def pixels_influenced_by_byte_index(
pixels: Iterable[palette.DHGRColours],
idx: int) -> Iterable[palette.DHGRColours]:
pixels: str,
idx: int) -> str:
"""Return subset of pixels that are influenced by given byte index (0..4)"""
start, end = {
0: (0, 1),
@@ -93,52 +97,6 @@ def pixels_influenced_by_byte_index(
return pixels[start:end + 1]
# Don't even consider insertions and deletions into the string, they don't
# make sense for comparing pixel strings
insert_costs = np.ones(128, dtype=np.float64) * 100000
delete_costs = np.ones(128, dtype=np.float64) * 100000
# Smallest substitution value is ~20 from palette.diff_matrix, i.e.
# we always prefer to transpose 2 pixels rather than substituting colours.
transpose_costs = np.ones((128, 128), dtype=np.float64) * 10
substitute_costs = np.zeros((128, 128), dtype=np.float64)
# Substitution costs to use when evaluating other potential offsets at which
# to store a content byte. We penalize more harshly for introducing
# errors that alter pixel colours, since these tend to be very
# noticeable as visual noise.
error_substitute_costs = np.zeros((128, 128), dtype=np.float64)
def make_substitute_costs():
# Penalty for changing colour
for i, c in enumerate(PIXEL_CHARS):
for j, d in enumerate(PIXEL_CHARS):
cost = palette.diff_matrix[i, j]
substitute_costs[(ord(c), ord(d))] = cost # / 20
substitute_costs[(ord(d), ord(c))] = cost # / 20
error_substitute_costs[(ord(c), ord(d))] = 5 * cost # / 4
error_substitute_costs[(ord(d), ord(c))] = 5 * cost # / 4
make_substitute_costs()
@functools.lru_cache(None)
def edit_distance(a, b, error: bool):
res = weighted_levenshtein.dam_lev(
a, b,
insert_costs=insert_costs,
delete_costs=delete_costs,
substitute_costs=error_substitute_costs if error else substitute_costs,
)
assert res == 0 or (1 <= res < 2 ** 16), res
return res
@functools.lru_cache(None)
def int28_to_pixels(int28):
return tuple(
@@ -170,7 +128,77 @@ def map_int8_to_mask32_3(int8):
return int8 << 20
def make_edit_distance():
class EditDistanceParams:
# Don't even consider insertions and deletions into the string, they don't
# make sense for comparing pixel strings
insert_costs = np.ones(128, dtype=np.float64) * 100000
delete_costs = np.ones(128, dtype=np.float64) * 100000
# Smallest substitution value is ~20 from palette.diff_matrices, i.e.
# we always prefer to transpose 2 pixels rather than substituting colours.
transpose_costs = np.ones((128, 128), dtype=np.float64) * 10
substitute_costs = np.zeros((128, 128), dtype=np.float64)
# Substitution costs to use when evaluating other potential offsets at which
# to store a content byte. We penalize more harshly for introducing
# errors that alter pixel colours, since these tend to be very
# noticeable as visual noise.
error_substitute_costs = np.zeros((128, 128), dtype=np.float64)
def compute_diff_matrix(pal: Type[palette.BasePalette]):
# Compute matrix of CIE2000 delta values for this pal, representing
# perceptual distance between colours.
dm = np.ndarray(shape=(16, 16), dtype=np.int)
for colour1, a in pal.RGB.items():
alab = colormath.color_conversions.convert_color(
a, colormath.color_objects.LabColor)
for colour2, b in pal.RGB.items():
blab = colormath.color_conversions.convert_color(
b, colormath.color_objects.LabColor)
dm[colour1.value, colour2.value] = int(
colormath.color_diff.delta_e_cie2000(alab, blab))
return dm
def make_substitute_costs(pal: Type[palette.BasePalette]):
edp = EditDistanceParams()
diff_matrix = compute_diff_matrix(pal)
# Penalty for changing colour
for i, c in enumerate(PIXEL_CHARS):
for j, d in enumerate(PIXEL_CHARS):
cost = diff_matrix[i, j]
edp.substitute_costs[(ord(c), ord(d))] = cost # / 20
edp.substitute_costs[(ord(d), ord(c))] = cost # / 20
edp.error_substitute_costs[(ord(c), ord(d))] = 5 * cost # / 4
edp.error_substitute_costs[(ord(d), ord(c))] = 5 * cost # / 4
return edp
@functools.lru_cache(None)
def edit_distance(
edp: EditDistanceParams,
a: str,
b: str,
error: bool) -> np.float64:
res = weighted_levenshtein.dam_lev(
a, b,
insert_costs=edp.insert_costs,
delete_costs=edp.delete_costs,
substitute_costs=(
edp.error_substitute_costs if error else edp.substitute_costs),
)
assert res == 0 or (1 <= res < 2 ** 16), res
return res
def make_edit_distance(edp: EditDistanceParams):
edit = [
np.zeros(shape=(2 ** 16), dtype=np.int16),
np.zeros(shape=(2 ** 24), dtype=np.int16),
@@ -191,8 +219,8 @@ def make_edit_distance():
second_pixels = pixels_influenced_by_byte_index(
pixel_string(int28_to_pixels(second)), 0)
edit[0][pair] = edit_distance(first_pixels, second_pixels,
error=False)
edit[0][pair] = edit_distance(
edp, first_pixels, second_pixels, error=False)
first = map_int8_to_mask32_3(i)
second = map_int8_to_mask32_3(j)
@@ -202,8 +230,8 @@ def make_edit_distance():
second_pixels = pixels_influenced_by_byte_index(
pixel_string(int28_to_pixels(second)), 3)
edit[3][pair] = edit_distance(first_pixels, second_pixels,
error=False)
edit[3][pair] = edit_distance(
edp, first_pixels, second_pixels, error=False)
for i in range(2 ** 12):
print(i)
@@ -218,8 +246,8 @@ def make_edit_distance():
second_pixels = pixels_influenced_by_byte_index(
pixel_string(int28_to_pixels(second)), 1)
edit[1][pair] = edit_distance(first_pixels, second_pixels,
error=False)
edit[1][pair] = edit_distance(
edp, first_pixels, second_pixels, error=False)
first = map_int12_to_mask32_2(i)
second = map_int12_to_mask32_2(j)
@@ -229,22 +257,23 @@ def make_edit_distance():
second_pixels = pixels_influenced_by_byte_index(
pixel_string(int28_to_pixels(second)), 2)
edit[2][pair] = edit_distance(first_pixels, second_pixels,
error=False)
edit[2][pair] = edit_distance(
edp, first_pixels, second_pixels, error=False)
return edit
def main():
edit = make_edit_distance()
for p in palette.PALETTES.values():
print("Processing palette %s" % p)
edp = make_substitute_costs(p)
edit = make_edit_distance(edp)
# TODO: error distance matrices
with bz2.open(
"transcoder/edit_distance.pickle.bz2", "wb",
compresslevel=9) as out:
pickle.dump(
edit, out, protocol=pickle.HIGHEST_PROTOCOL)
# TODO: error distance matrices
data = "transcoder/data/palette_%d_edit_distance.pickle" \
".bz2" % p.ID.value
with bz2.open(data, "wb", compresslevel=9) as out:
pickle.dump(edit, out, protocol=pickle.HIGHEST_PROTOCOL)
if __name__ == "__main__":