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tools: rle_encode: Optimize the 2-bit encoding slightly

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This results in a image that is entirely ROMable.
This commit is contained in:
Daniel Thompson 2020-04-10 20:20:48 +01:00
parent a1badfd95d
commit 906c313e49
1 changed files with 36 additions and 17 deletions
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53
tools/rle_encode.py
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@ -59,6 +59,8 @@ def encode_2bit(im):
this encoding is about 30% larger than a 1-bit encoding.
"""
pixels = im.load()
assert(im.width <= 255)
assert(im.height <= 255)
rle = []
rl = 0
@ -87,6 +89,11 @@ def encode_2bit(im):
else:
rle.append((px << 6) + rl)
# Issue the descriptor
rle.append(2)
rle.append(im.width)
rle.append(im.height)
for y in range(im.height):
for x in range(im.width):
newpx = pixels[x, y]
@ -105,7 +112,7 @@ def encode_2bit(im):
# Handle the final run
encode_pixel(px, rl)
return (im.width, im.height, bytes(rle))
return bytes(rle)
def encode_8bit(im):
"""Experimental 8-bit RLE encoder.
@ -212,29 +219,41 @@ parser.add_argument('--2bit', action='store_true', dest='twobit',
help='Generate 2-bit image')
parser.add_argument('--8bit', action='store_true', dest='eightbit',
help='Generate 8-bit image')
args = parser.parse_args()
extra_indent = ' ' * args.indent
if args.eightbit:
encoder = encode_8bit
depth = 8
elif args.twobit:
encoder = encode_2bit
depth = 2
else:
encoder = encode
depth =1
for fname in args.files:
if args.eightbit:
image = encode_8bit(Image.open(fname))
depth = 8
elif args.twobit:
image = encode_2bit(Image.open(fname))
depth = 2
else:
image = encode(Image.open(fname))
depth = 1
image = encoder(Image.open(fname))
if args.c:
render_c(image, fname)
else:
print(f'# {depth}-bit RLE, generated from {fname}, {len(image[2])} bytes')
# Split the bytestring to ensure each line is short enough to be absorbed
# on the target if needed.
#print(f'{varname(fname)} = {image}')
(x, y, pixels) = image
extra_indent = ' ' * args.indent
print(f'{extra_indent}{varname(fname)} = (\n{extra_indent} {x}, {y},')
if len(image) == 3:
print(f'{extra_indent}# {depth}-bit RLE, generated from {fname}, '
f'{len(image[2])} bytes')
(x, y, pixels) = image
print(f'{extra_indent}{varname(fname)} = (')
print(f'{extra_indent} {x}, {y},')
else:
print(f'{extra_indent}# {depth}-bit RLE, generated from {fname}, '
f'{len(image)} bytes')
pixels = image[3:]
print(f'{extra_indent}{varname(fname)} = (')
print(f'{extra_indent} {image[0:1]}')
print(f'{extra_indent} {image[1:3]}')
# Split the bytestring to ensure each line is short enough to
# be absorbed on the target if needed.
for i in range(0, len(pixels), 16):
print(f'{extra_indent} {pixels[i:i+16]}')
print(f'{extra_indent})')