imaging.images2ims — GRASS Python Library documentation

# Source code for imaging.images2ims

    #   Copyright (C) 2012, Almar Klein
    #
    #   This code is subject to the (new) BSD license:
    #
    #   Redistribution and use in source and binary forms, with or without
    #   modification, are permitted provided that the following conditions are met:
    #     * Redistributions of source code must retain the above copyright
    #       notice, this list of conditions and the following disclaimer.
    #     * Redistributions in binary form must reproduce the above copyright
    #       notice, this list of conditions and the following disclaimer in the
    #       documentation and/or other materials provided with the distribution.
    #     * Neither the name of the <organization> nor the
    #       names of its contributors may be used to endorse or promote products
    #       derived from this software without specific prior written permission.
    #
    # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    # ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
    # DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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    # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    """ Module images2ims

    Use PIL to create a series of images.

    """

    import os

    try:
        import numpy as np
    except ImportError:
        np = None

    try:
        import PIL
    except ImportError:
        PIL = None

    def checkImages(images):
        """Check numpy images and correct intensity range etc.
        The same for all movie formats.

        :param images:
        """
        # Init results
        images2 = []

        for im in images:
            if PIL and isinstance(im, PIL.Image.Image):
                # We assume PIL images are alright
                images2.append(im)

            elif np and isinstance(im, np.ndarray):
                # Check and convert dtype
                if im.dtype == np.uint8:
                    images2.append(im)  # Ok
                elif im.dtype in [np.float32, np.float64]:
                    theMax = im.max()
                    if theMax > 128 and theMax < 300:
                        pass  # assume 0:255
                    else:
                        im = im.copy()
                        im[im < 0] = 0
                        im[im > 1] = 1
                        im *= 255
                    images2.append(im.astype(np.uint8))
                else:
                    im = im.astype(np.uint8)
                    images2.append(im)
                # Check size
                if im.ndim == 2:
                    pass  # ok
                elif im.ndim == 3:
                    if im.shape[2] not in [3, 4]:
                        raise ValueError("This array can not represent an image.")
                else:
                    raise ValueError("This array can not represent an image.")
            else:
                raise ValueError("Invalid image type: " + str(type(im)))

        # Done
        return images2

    def _getFilenameParts(filename):
        if "*" in filename:
            return tuple(filename.split("*", 1))
        else:
            return os.path.splitext(filename)

    def _getFilenameWithFormatter(filename, N):
        # Determine sequence number formatter
        formatter = "%04i"
        if N < 10:
            formatter = "%i"
        elif N < 100:
            formatter = "%02i"
        elif N < 1000:
            formatter = "%03i"

        # Insert sequence number formatter
        part1, part2 = _getFilenameParts(filename)
        return part1 + formatter + part2

    def _getSequenceNumber(filename, part1, part2):
        # Get string bit
        seq = filename[len(part1) : -len(part2)]
        # Get all numeric chars
        seq2 = ""
        for c in seq:
            if c in "0123456789":
                seq2 += c
            else:
                break
        # Make int and return
        return int(seq2)

    def writeIms(filename, images):
        """Export movie to a series of image files. If the filenenumber
        contains an asterix, a sequence number is introduced at its
        location. Otherwise the sequence number is introduced right
        before the final dot.

        To enable easy creation of a new directory with image files,
        it is made sure that the full path exists.

        Images should be a list consisting of PIL images or numpy arrays.
        The latter should be between 0 and 255 for integer types, and
        between 0 and 1 for float types.

        :param filename:
        :param images:
        """

        # Check PIL
        if PIL is None:
            raise RuntimeError("Need PIL to write series of image files.")

        # Check images
        images = checkImages(images)

        # Get dirname and filename
        filename = os.path.abspath(filename)
        dirname, filename = os.path.split(filename)

        # Create dir(s) if we need to
        if not os.path.isdir(dirname):
            os.makedirs(dirname)

        # Insert formatter
        filename = _getFilenameWithFormatter(filename, len(images))

        # Write
        seq = 0
        for frame in images:
            seq += 1
            # Get filename
            fname = os.path.join(dirname, filename % seq)
            # Write image
            if np and isinstance(frame, np.ndarray):
                frame = PIL.Image.fromarray(frame)
            frame.save(fname)

    def readIms(filename, asNumpy=True):
        """readIms(filename, asNumpy=True)

        Read images from a series of images in a single directory. Returns a
        list of numpy arrays, or, if asNumpy is false, a list if PIL images.

        :param filename:
        :param bool asNumpy:
        """

        # Check PIL
        if PIL is None:
            raise RuntimeError("Need PIL to read a series of image files.")

        # Check Numpy
        if asNumpy and np is None:
            raise RuntimeError("Need Numpy to return numpy arrays.")

        # Get dirname and filename
        filename = os.path.abspath(filename)
        dirname, filename = os.path.split(filename)

        # Check dir exists
        if not os.path.isdir(dirname):
            raise OSError("Directory not found: " + str(dirname))

        # Get two parts of the filename
        part1, part2 = _getFilenameParts(filename)

        # Init images
        images = []

        # Get all files in directory
        for fname in os.listdir(dirname):
            if fname.startswith(part1) and fname.endswith(part2):
                # Get sequence number
                nr = _getSequenceNumber(fname, part1, part2)
                # Get Pil image and store copy (to prevent keeping the file)
                im = PIL.Image.open(os.path.join(dirname, fname))
                images.append((im.copy(), nr))

        # Sort images
        images.sort(key=lambda x: x[1])
        images = [im[0] for im in images]

        # Convert to numpy if needed
        if asNumpy:
            images2 = images
            images = []
            for im in images2:
                # Make without palette
                if im.mode == "P":
                    im = im.convert()
                # Make numpy array
                a = np.asarray(im)
                if len(a.shape) == 0:
                    raise MemoryError("Too little memory to convert PIL image to array")
                # Add
                images.append(a)

        # Done
        return images

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