def read2DImageROI(path, dimensions, interval, pixelType=UnsignedShortType, header=0, byte_order=ByteOrder.LITTLE_ENDIAN):
""" Read a region of interest (the interval) of an image in a file.
Assumes the image is written with the first dimension moving slowest.
path: the file path to the image file.
dimensions: a sequence of integer values e.g. [512, 512, 512]
interval: two sequences of integer values defining the min and max coordinates, e.g.
[[20, 0], [400, 550]]
pixeltype: e.g. UnsignedShortType, FloatType
header: defaults to zero, the number of bytes between the start of the file and the start of the image data.
Supports only these types: UnsignedByteType, UnsignedShortType, FloatType.
Returns an ArrayImg of the given type.
"""
ra = RandomAccessFile(path, 'r')
try:
width, height = dimensions
minX, minY = interval[0]
maxX, maxY = interval[1]
roi_width, roi_height = maxX - minX + 1, maxY - minY + 1
tailX = width - roi_width - minX
#print minX, minY
#print maxX, maxY
#print roi_width, roi_height
size = roi_width * roi_height
n_bytes_per_pixel = pixelType().getBitsPerPixel() / 8
#print n_bytes_per_pixel
bytes = zeros(size * n_bytes_per_pixel, 'b')
# Read only the 2D ROI
ra.seek(header + (minY * width + minX) * n_bytes_per_pixel)
for h in xrange(roi_height):
ra.readFully(bytes, h * roi_width * n_bytes_per_pixel, roi_width * n_bytes_per_pixel)
ra.skipBytes((tailX + minX) * n_bytes_per_pixel)
# Make an image
roiDims = [roi_width, roi_height]
if UnsignedByteType == pixelType:
return ArrayImgs.unsignedBytes(bytes, roiDims)
if UnsignedShortType == pixelType:
shorts = zeros(size, 'h')
ByteBuffer.wrap(bytes).order(byte_order).asShortBuffer().get(shorts)
return ArrayImgs.shorts(shorts, roiDims)
if FloatType == pixelType:
floats = zeros(size, 'f')
ByteBuffer.wrap(bytes).order(byte_order).asFloatBuffer().get(floats)
return ArrayImgs.floats(floats, roiDims)
finally:
ra.close()
def readFIBSEMdat(path, channel_index=-1, header=1024, magic_number=3555587570):
""" Read a file from Shan Xu's FIBSEM software, where two channels are interleaved.
Assumes channels are stored in 16-bit.
path: the file path to the .dat file.
channel_index: the 0-based index of the channel to parse, or -1 (default) for all.
header: defaults to a length of 1024 bytes
magic_number: defaults to that for version 8 of Shan Xu's .dat image file format.
"""
ra = RandomAccessFile(path, 'r')
try:
# Check the magic number
ra.seek(0)
if ra.readInt() & 0xffffffff != magic_number:
print "Magic number mismatch"
return None
# Read the number of channels
ra.seek(32)
numChannels = ra.readByte() & 0xff # a single byte as unsigned integer
# Parse width and height
ra.seek(100)
width = ra.readInt()
ra.seek(104)
height = ra.readInt()
print numChannels, width, height
# Read the whole interleaved pixel array
ra.seek(header)
bytes = zeros(width * height * 2 * numChannels, 'b') # 2 for 16-bit
ra.read(bytes)
print "read", len(bytes), "bytes" # takes ~2 seconds
# Parse as 16-bit array
sb = ByteBuffer.wrap(bytes).order(ByteOrder.BIG_ENDIAN).asShortBuffer()
shorts = zeros(width * height * numChannels, 'h')
sb.get(shorts)
# Deinterleave channels
# With Weaver: fast
channels = w.deinterleave(shorts, numChannels, channel_index)
# With python array sampling: very slow, and not just from iterating whole array once per channel
# seq = xrange(numChannels) if -1 == channel_index else [channel_index]
#channels = [shorts[i::numChannels] for i in seq]
# With clojure: extremely slow, may be using reflection unexpectedly
#channels = deinterleave.invoke(shorts, numChannels)
print len(channels)
# Shockingly, these values are signed shorts, not unsigned!
return [ArrayImgs.shorts(s, [width, height]) for s in channels]
finally:
ra.close()