Read Metadata and Image data from 10-bit DPX files in Python 3

dpx.py

"""
dpx.py

Read Metadata and Image data from 10-bit DPX files in Python 3

Copyright (c) 2016 Jack Doerner

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
""" 

import struct
import numpy as np

test_filename = "test.dpx"

orientations = {
	0: "Left to Right, Top to Bottom",
	1: "Right to Left, Top to Bottom",
	2: "Left to Right, Bottom to Top",
	3: "Right to Left, Bottom to Top",
	4: "Top to Bottom, Left to Right",
	5: "Top to Bottom, Right to Left",
	6: "Bottom to Top, Left to Right",
	7: "Bottom to Top, Right to Left"
}

descriptors = {
	1: "Red",
	2: "Green",
	3: "Blue",
	4: "Alpha",
	6: "Luma (Y)",
	7: "Color Difference",
	8: "Depth (Z)",
	9: "Composite Video",
	50: "RGB",
	51: "RGBA",
	52: "ABGR",
	100: "Cb, Y, Cr, Y (4:2:2)",
	102: "Cb, Y, Cr (4:4:4)",
	103: "Cb, Y, Cr, A (4:4:4:4)"
}

packings = {
	0: "Packed into 32-bit words",
	1: "Filled to 32-bit words, Padding First",
	2: "Filled to 32-bit words, Padding Last"
}

encodings = {
	0: "No encoding",
	1: "Run Length Encoding"
}

transfers = {
	1: "Printing Density",
	2: "Linear",
	3: "Logarithmic",
	4: "Unspecified Video",
	5: "SMPTE 274M",
	6: "ITU-R 709-4",
	7: "ITU-R 601-5 system B or G",
	8: "ITU-R 601-5 system M",
	9: "Composite Video (NTSC)",
	10: "Composite Video (PAL)",
	11: "Z (Linear Depth)",
	12: "Z (Homogenous Depth)"
}

colorimetries = {
	1: "Printing Density",
	4: "Unspecified Video",
	5: "SMPTE 274M",
	6: "ITU-R 709-4",
	7: "ITU-R 601-5 system B or G",
	8: "ITU-R 601-5 system M",
	9: "Composite Video (NTSC)",
	10: "Composite Video (PAL)"
}

propertymap = [
	#(field name, offset, length, type)

	('magic', 0, 4, 'magic'),
	('offset', 4, 4, 'I'),
	('dpx_version', 8, 8, 'utf8'),
	('file_size', 16, 4, 'I'),
	('ditto', 20, 4, 'I'),
	('filename', 36, 100, 'utf8'),
	('timestamp', 136, 24, 'utf8'),
	('creator', 160, 100, 'utf8'),
	('project_name', 260, 200, 'utf8'),
	('copyright', 460, 200, 'utf8'),
	('encryption_key', 660, 4, 'I'),

	('orientation', 768, 2, 'H'),
	('image_element_count', 770, 2, 'H'),
	('width', 772, 4, 'I'),
	('height', 776, 4, 'I'),

	('data_sign', 780, 4, 'I'),
	('descriptor', 800, 1, 'B'),
	('transfer_characteristic', 801, 1, 'B'),
	('colorimetry', 802, 1, 'B'),
	('depth', 803, 1, 'B'),
	('packing', 804, 2, 'H'),
	('encoding', 806, 2, 'H'),
	('line_padding', 812, 4, 'I'),
	('image_padding', 816, 4, 'I'),
	('image_element_description', 820, 32, 'utf8'),

	('input_device_name', 1556, 32, 'utf8'),
	('input_device_sn', 1588, 32, 'utf8')
]

def readDPXMetaData(f):
	f.seek(0)
	bytes = f.read(4)
	magic = bytes.decode(encoding='UTF-8')
	if magic != "SDPX" and magic != "XPDS":
		return None
	endianness = ">" if magic == "SDPX" else "<"

	meta = {}

	for p in propertymap:
		f.seek(p[1])
		bytes = f.read(p[2])
		if p[3] == 'magic':
			meta[p[0]] = bytes.decode(encoding='UTF-8')
			meta['endianness'] = "be" if magic == "SDPX" else "le"
		elif p[3] == 'utf8':
			meta[p[0]] = bytes.decode(encoding='UTF-8')
		elif p[3] == 'B':
			meta[p[0]] = struct.unpack(endianness + 'B', bytes)[0]
		elif p[3] == 'H':
			meta[p[0]] = struct.unpack(endianness + 'H', bytes)[0]
		elif p[3] == 'I':
			meta[p[0]] = struct.unpack(endianness + 'I', bytes)[0]

	return meta

def readDPXImageData(f, meta):
	if meta['depth'] != 10 or meta['packing'] != 1 or meta['encoding'] != 0 or meta['descriptor'] != 50:
		return None

	width = meta['width']
	height = meta['height']
	image = np.empty((height, width, 3), dtype=float)

	f.seek(meta['offset'])
	raw = np.fromfile(f, dtype=np.dtype(np.int32), count=width*height, sep="")
	raw = raw.reshape((height,width))

	if meta['endianness'] == 'be':
		raw = raw.byteswap()

	image[:,:,0] = (((raw >> 22) & 0x000003FF)/ 0x000003FF)
	image[:,:,1] = (((raw >> 12) & 0x000003FF)/ 0x000003FF)
	image[:,:,2] = (((raw >> 2) & 0x000003FF)/ 0x000003FF)

	return image

def writeDPX(f, image, meta):
	endianness = ">" if meta['endianness'] == 'be' else "<"
	for p in propertymap:
		if p[0] in meta:
			f.seek(p[1])
			if p[3] == 'magic':
				bytes = ('SDPX' if meta['endianness'] == 'be' else 'XPDS').encode(encoding='UTF-8')
			elif p[3] == 'utf8':
				bytes = meta[p[0]].encode(encoding='UTF-8')
			else:
				bytes = struct.pack(endianness + p[3], meta[p[0]])
			f.write(bytes)

	raw = ((((image[:,:,0] * 0x000003FF).astype(np.dtype(np.int32)) & 0x000003FF) << 22) 
			| (((image[:,:,1] * 0x000003FF).astype(np.dtype(np.int32)) & 0x000003FF) << 12)
			| (((image[:,:,2] * 0x000003FF).astype(np.dtype(np.int32)) & 0x000003FF) << 2)
		)

	if meta['endianness'] == 'be':
		raw = raw.byteswap()

	f.seek(meta['offset'])
	raw.tofile(f, sep="")

if __name__ == "__main__":
	with open(test_filename, "rb") as f:
		meta = readDPXMetaData(f)
		if meta is None:
			print("Invalid File")
		else:
			import binascii
			print("\nFILE INFORMATION HEADER")

			print("Endianness:","Big Endian" if meta['endianness'] == ">" else "Little Endian")
			print("Image Offset (Bytes):",meta['offset'])
			print("DPX Version:",meta['dpx_version'])
			print("File Size (Bytes):",meta['file_size'])
			print("Ditto Flag:","New Frame" if meta['ditto'] else "Same as Previous Frame")
			print("Image Filename:",meta['filename'])
			print("Creation Timestamp:",meta['timestamp'])
			print("Creator:",meta['creator'])
			print("Project Name:",meta['project_name'])
			print("Copyright:",meta['copyright'])
			print("Encryption Key:","Unencrypted" if meta['encryption_key'] == 0xFFFFFFFF else binascii.hexlify(bin(meta['encryption_key'])))


			print("\nIMAGE INFORMATION HEADER")
			print("Orientation:", orientations[meta['orientation']] if meta['orientation'] in orientations else "unknown")
			print("Image Element Count:", meta['image_element_count'])
			print("Width:", meta['width'])
			print("Height:", meta['height'])

			print("\nIMAGE ELEMENT 1")
			print("Data Sign:", "signed" if meta['data_sign'] == 1 else "unsigned")
			print("Descriptor:", descriptors[meta['descriptor']] if meta['descriptor'] in descriptors else "unknown")
			print("Transfer:",transfers[meta['transfer_characteristic']] if meta['transfer_characteristic'] in transfers else "unknown")
			print("Colorimetry:",colorimetries[meta['colorimetry']] if meta['colorimetry'] in colorimetries else "unknown")
			print("Bit Depth:",meta['depth'])
			print("Packing:",packings[meta['packing']] if meta['packing'] in packings else "unknown")
			print("Encoding:",encodings[meta['encoding']] if meta['encoding'] in encodings else "unknown")
			print("End of Line Padding:",meta['line_padding'])
			print("End of Image Padding:",meta['image_padding'])
			print("Image Element Description:",meta['image_element_description'])

			print("\nIMAGE SOURCE INFORMATION HEADER")
			print("Input Device Name:",meta['input_device_name'])
			print("Input Device Serial Number:",meta['input_device_sn'])

			print("\n")

			image = readDPXImageData(f, meta)

			if image is None:
				print("DPX Type not Implemented")
			else:
				from matplotlib import pyplot as plt
				plt.imshow(image, interpolation='nearest')
				plt.show()