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#!/usr/bin/env python3
#
# Turn a Futhark value encoded in the binary data format in some file
# into a PNG image in another file. Very little error checking is
# done. The following input types are supported:
#
# [height][width]u8
# [height][width]i32
# [height][width]u32
#
# [height][width]f32
# [height][width]f64
#
# [height][width][3]i8
# [height][width][3]u8
#
# Requires purepng and Numpy.
#
# Example:
#
# $ cat input | ./some-futhark-program | tools/data2png.py /dev/stdin out.png
import sys
import struct
import numpy as np
import png
if "purepng" not in png.__file__:
print("data2png works only with purepng, not pypng.", file=sys.stderr)
sys.exit(1)
def read_image(f):
# Skip binary header.
assert f.read(1) == b"b", "Invalid binary header"
assert f.read(1) == b"\2", "Invalid binary format"
rank = np.int8(struct.unpack("<B", f.read(1))[0])
type = f.read(4)
if rank == 2 and type == b" u8":
height = np.int64(struct.unpack("<Q", f.read(8))[0])
width = np.int64(struct.unpack("<Q", f.read(8))[0])
array = np.frombuffer(f.read(height * width), dtype=np.uint8).reshape(
height, width
)
return (width, height, array)
if rank == 2 and type in [b" i32", b" u32", b" f32", b" f64"]:
height = np.int64(struct.unpack("<Q", f.read(8))[0])
width = np.int64(struct.unpack("<Q", f.read(8))[0])
image = np.empty((height, width, 3), dtype=np.uint8)
if type == b" f32":
array = np.frombuffer(
f.read(height * width * 4), dtype=np.float32
).reshape(height, width)
image[:, :, 0] = image[:, :, 1] = image[:, :, 2] = np.uint8(
np.float32(array) * 255
)
if type == b" f64":
array = np.frombuffer(
f.read(height * width * 8), dtype=np.float64
).reshape(height, width)
image[:, :, 0] = image[:, :, 1] = image[:, :, 2] = np.uint8(
np.float64(array) * 255
)
else:
array = np.frombuffer(
f.read(height * width * 4), dtype=np.uint32
).reshape(height, width)
image[:, :, 0] = (array & 0xFF0000) >> 16
image[:, :, 1] = (array & 0xFF00) >> 8
image[:, :, 2] = array & 0xFF
return (width, height, np.reshape(image, (height, width * 3)))
elif rank == 3 and type in [b" i8", b" u8"]:
height = np.int64(struct.unpack("<Q", f.read(8))[0])
width = np.int64(struct.unpack("<Q", f.read(8))[0])
depth = np.int64(struct.unpack("<Q", f.read(8))[0])
assert depth == 3
image = np.frombuffer(
f.read(height * width * depth), dtype=np.uint8
).reshape(height, width, depth)
return (width, height, np.reshape(image, (height, width * 3)))
else:
raise Exception(
"Invalid rank '{}' and element type {}".format(rank, type)
)
if __name__ == "__main__":
infile = sys.argv[1]
outfile = sys.argv[2]
with open(infile, "rb") as f_in:
width, height, img = read_image(f_in)
with open(outfile, "wb") as f_out:
w = png.Writer(width=width, height=height, alpha=False)
w.write(f_out, img)
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