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'''
Code for handling files that are band interleaved by pixel (BIP).
'''
from __future__ import absolute_import, division, print_function, unicode_literals
import array
import logging
import numpy as np
import os
import sys
import spectral as spy
from .spyfile import SpyFile, MemmapFile
from spectral.utilities.python23 import typecode, tobytes, frombytes
byte_typecode = typecode('b')
class BipFile(SpyFile, MemmapFile):
'''
A class to interface image files stored with bands interleaved by pixel.
'''
def __init__(self, params, metadata=None):
self.interleave = spy.BIP
if metadata is None:
metadata = {}
SpyFile.__init__(self, params, metadata)
self._memmap = self._open_memmap('r')
def _open_memmap(self, mode):
logger = logging.getLogger('spectral')
if (os.path.getsize(self.filename) < sys.maxsize):
try:
(R, C, B) = self.shape
return np.memmap(self.filename, dtype=self.dtype, mode=mode,
offset=self.offset, shape=self.shape)
except:
logger.debug('Unable to create memmap interface.')
return None
else:
return None
def read_band(self, band, use_memmap=True):
'''Reads a single band from the image.
Arguments:
`band` (int):
Index of band to read.
`use_memmap` (bool, default True):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Returns:
:class:`numpy.ndarray`
An `MxN` array of values for the specified band.
'''
if self._memmap is not None and use_memmap is True:
data = np.array(self._memmap[:, :, band])
if self.scale_factor != 1:
data = data / float(self.scale_factor)
return data
vals = array.array(byte_typecode)
delta = self.sample_size * (self.nbands - 1)
nVals = self.nrows * self.ncols
sample_size = self.sample_size
f = self.fid
f.seek(self.offset + self.sample_size * band, 0)
# Pixel format is BIP
for i in range(nVals - 1):
vals.fromfile(f, sample_size)
f.seek(delta, 1)
vals.fromfile(f, sample_size)
arr = np.frombuffer(tobytes(vals), dtype=self.dtype)
arr = arr.reshape(self.nrows, self.ncols)
if self.scale_factor != 1:
return arr / float(self.scale_factor)
return arr
def read_bands(self, bands, use_memmap=True):
'''Reads multiple bands from the image.
Arguments:
`bands` (list of ints):
Indices of bands to read.
`use_memmap` (bool, default True):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Returns:
:class:`numpy.ndarray`
An `MxNxL` array of values for the specified bands. `M` and `N`
are the number of rows & columns in the image and `L` equals
len(`bands`).
'''
if self._memmap is not None and use_memmap is True:
data = np.array(self._memmap[:, :, bands])
if self.scale_factor != 1:
data = data / float(self.scale_factor)
return data
vals = array.array(byte_typecode)
offset = self.offset
delta = self.sample_size * self.nbands
nVals = self.nrows * self.ncols
sample_size = self.sample_size
# Increments between bands
delta_b = list(bands[:])
for i in range(len(delta_b)):
delta_b[i] *= self.sample_size
f = self.fid
# Pixel format is BIP
for i in range(nVals):
pixelOffset = offset + i * delta
for j in range(len(bands)):
f.seek(pixelOffset + delta_b[j], 0) # Next band
vals.fromfile(f, sample_size)
arr = np.frombuffer(tobytes(vals), dtype=self.dtype)
arr = arr.reshape(self.nrows, self.ncols, len(bands))
if self.scale_factor != 1:
return arr / float(self.scale_factor)
return arr
def read_pixel(self, row, col, use_memmap=True):
'''Reads the pixel at position (row,col) from the file.
Arguments:
`row`, `col` (int):
Indices of the row & column for the pixel
`use_memmap` (bool, default True):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Returns:
:class:`numpy.ndarray`
A length-`B` array, where `B` is the number of image bands.
'''
if self._memmap is not None and use_memmap is True:
data = np.array(self._memmap[row, col, :])
if self.scale_factor != 1:
data = data / float(self.scale_factor)
return data
vals = array.array(byte_typecode)
f = self.fid
f.seek(self.offset + self.sample_size
* self.nbands * (row * self.ncols + col), 0)
# Pixel format is BIP so read entire pixel.
vals.fromfile(f, self.nbands * self.sample_size)
pixel = np.frombuffer(tobytes(vals), dtype=self.dtype)
if self.scale_factor != 1:
return pixel / float(self.scale_factor)
return pixel
def read_subregion(self, row_bounds, col_bounds, bands=None,
use_memmap=True):
'''
Reads a contiguous rectangular sub-region from the image.
Arguments:
`row_bounds` (2-tuple of ints):
(a, b) -> Rows a through b-1 will be read.
`col_bounds` (2-tuple of ints):
(a, b) -> Columnss a through b-1 will be read.
`bands` (list of ints):
Optional list of bands to read. If not specified, all bands
are read.
`use_memmap` (bool, default True):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Returns:
:class:`numpy.ndarray`
An `MxNxL` array.
'''
if self._memmap is not None and use_memmap is True:
if bands is None:
data = np.array(self._memmap[row_bounds[0]: row_bounds[1],
col_bounds[0]: col_bounds[1], :])
else:
data = np.array(self._memmap[row_bounds[0]: row_bounds[1],
col_bounds[0]: col_bounds[1],
bands])
if self.scale_factor != 1:
data = data / float(self.scale_factor)
return data
offset = self.offset
nbands = self.nbands
nSubRows = row_bounds[1] - row_bounds[0] # Rows in sub-image
nSubCols = col_bounds[1] - col_bounds[0] # Cols in sub-image
d_row = self.sample_size * self.ncols * self.nbands
colStartPos = col_bounds[0] * self.sample_size * self.nbands
vals = array.array(byte_typecode)
nVals = self.nrows * self.ncols
sample_size = self.sample_size
# Increments between bands
if bands is not None:
allBands = 0
nSubBands = len(bands)
delta_b = bands[:]
for i in range(len(delta_b)):
delta_b[i] *= self.sample_size
else:
allBands = 1
nSubBands = self.nbands
f = self.fid
# Pixel format is BIP
for i in range(row_bounds[0], row_bounds[1]):
f.seek(offset + i * d_row + colStartPos, 0)
rowPos = f.tell()
if allBands:
# This is the simple one
vals.fromfile(f, nSubCols * nbands * sample_size)
else:
# Need to pull out specific bands for each column.
for j in range(nSubCols):
f.seek(rowPos + j * self.sample_size * self.nbands, 0)
pixelPos = f.tell()
for k in range(len(bands)):
f.seek(pixelPos + delta_b[k], 0) # Next band
vals.fromfile(f, sample_size)
arr = np.frombuffer(tobytes(vals), dtype=self.dtype)
arr = arr.reshape(nSubRows, nSubCols, nSubBands)
if self.scale_factor != 1:
return arr / float(self.scale_factor)
return arr
def read_subimage(self, rows, cols, bands=None, use_memmap=False):
'''
Reads arbitrary rows, columns, and bands from the image.
Arguments:
`rows` (list of ints):
Indices of rows to read.
`cols` (list of ints):
Indices of columns to read.
`bands` (list of ints):
Optional list of bands to read. If not specified, all bands
are read.
`use_memmap` (bool, default False):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Returns:
:class:`numpy.ndarray`
An `MxNxL` array, where `M` = len(`rows`), `N` = len(`cols`),
and `L` = len(bands) (or # of image bands if `bands` == None).
'''
if self._memmap is not None and use_memmap is True:
if bands is None:
data = np.array(self._memmap.take(rows, 0).take(cols, 1))
else:
data = np.array(
self._memmap.take(rows, 0).take(cols, 1).take(bands, 2))
if self.scale_factor != 1:
data = data / float(self.scale_factor)
return data
offset = self.offset
nbands = self.nbands
nSubRows = len(rows) # Rows in sub-image
nSubCols = len(cols) # Cols in sub-image
d_band = self.sample_size
d_col = d_band * self.nbands
d_row = d_col * self.ncols
vals = array.array(byte_typecode)
nVals = self.nrows * self.ncols
sample_size = self.sample_size
# Increments between bands
if bands is not None:
allBands = 0
nSubBands = len(bands)
else:
allBands = 1
bands = list(range(self.nbands))
nSubBands = self.nbands
f = self.fid
# Pixel format is BIP
for i in rows:
for j in cols:
if allBands:
f.seek(offset + i * d_row + j * d_col, 0)
vals.fromfile(f, nSubBands * sample_size)
else:
for k in bands:
f.seek(offset +
i * d_row +
j * d_col +
k * d_band, 0)
vals.fromfile(f, sample_size)
arr = np.frombuffer(tobytes(vals), dtype=self.dtype)
arr = arr.reshape(nSubRows, nSubCols, nSubBands)
if self.scale_factor != 1:
return arr / float(self.scale_factor)
return arr
def read_datum(self, i, j, k, use_memmap=True):
'''Reads the band `k` value for pixel at row `i` and column `j`.
Arguments:
`i`, `j`, `k` (integer):
Row, column and band index, respectively.
`use_memmap` (bool, default True):
Specifies whether the file's memmap interface should be used
to read the data. Setting this arg to True only has an effect
if a memmap is being used (i.e., if `img.using_memmap` is True).
Using this function is not an efficient way to iterate over bands or
pixels. For such cases, use readBands or readPixel instead.
'''
if self._memmap is not None and use_memmap is True:
datum = self._memmap[i, j, k]
if self.scale_factor != 1:
datum /= float(self.scale_factor)
return datum
vals = array.array(byte_typecode)
f = self.fid
f.seek(self.offset + self.sample_size
* (self.nbands * (i * self.ncols + j) + k), 0)
# Pixel format is BIP so read entire pixel.
vals.fromfile(f, self.sample_size)
arr = np.frombuffer(tobytes(vals), dtype=self.dtype)
return arr.tolist()[0] / float(self.scale_factor)
|
