IO.py

#!/usr/bin/env python3.4
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
import os
import re
import numpy as np
import uuid
from scipy import misc
import numpy as np
from PIL import Image
import sys


def read(file):
    if file.endswith('.float3'): return readFloat(file)
    elif file.endswith('.flo'): return readFlow(file)
    elif file.endswith('.ppm'): return readImage(file)
    elif file.endswith('.pgm'): return readImage(file)
    elif file.endswith('.png'): return readImage(file)
    elif file.endswith('.jpg'): return readImage(file)
    elif file.endswith('.pfm'): return readPFM(file)[0]
    else: raise Exception('don\'t know how to read %s' % file)

def write(file, data):
    if file.endswith('.float3'): return writeFloat(file, data)
    elif file.endswith('.flo'): return writeFlow(file, data)
    elif file.endswith('.ppm'): return writeImage(file, data)
    elif file.endswith('.pgm'): return writeImage(file, data)
    elif file.endswith('.png'): return writeImage(file, data)
    elif file.endswith('.jpg'): return writeImage(file, data)
    elif file.endswith('.pfm'): return writePFM(file, data)
    else: raise Exception('don\'t know how to write %s' % file)

def readPFM(file):
    file = open(file, 'rb')

    color = None
    width = None
    height = None
    scale = None
    endian = None

    header = file.readline().rstrip()
    if header.decode("ascii") == 'PF':
        color = True
    elif header.decode("ascii") == 'Pf':
        color = False
    else:
        raise Exception('Not a PFM file.')

    dim_match = re.match(r'^(\d+)\s(\d+)\s$', file.readline().decode("ascii"))
    if dim_match:
        width, height = list(map(int, dim_match.groups()))
    else:
        raise Exception('Malformed PFM header.')

    scale = float(file.readline().decode("ascii").rstrip())
    if scale < 0: # little-endian
        endian = '<'
        scale = -scale
    else:
        endian = '>' # big-endian

    data = np.fromfile(file, endian + 'f')
    shape = (height, width, 3) if color else (height, width)

    data = np.reshape(data, shape)
    data = np.flipud(data)
    return data, scale

def writePFM(file, image, scale=1):
    file = open(file, 'wb')

    color = None

    if image.dtype.name != 'float32':
        raise Exception('Image dtype must be float32.')

    image = np.flipud(image)

    if len(image.shape) == 3 and image.shape[2] == 3: # color image
        color = True
    elif len(image.shape) == 2 or len(image.shape) == 3 and image.shape[2] == 1: # greyscale
        color = False
    else:
        raise Exception('Image must have H x W x 3, H x W x 1 or H x W dimensions.')

    file.write('PF\n' if color else 'Pf\n'.encode())
    file.write('%d %d\n'.encode() % (image.shape[1], image.shape[0]))

    endian = image.dtype.byteorder

    if endian == '<' or endian == '=' and sys.byteorder == 'little':
        scale = -scale

    file.write('%f\n'.encode() % scale)

    image.tofile(file)

def readFlow(name):
    if name.endswith('.pfm') or name.endswith('.PFM'):
        return readPFM(name)[0][:,:,0:2]

    f = open(name, 'rb')

    header = f.read(4)
    if header.decode("utf-8") != 'PIEH':
        raise Exception('Flow file header does not contain PIEH')

    width = np.fromfile(f, np.int32, 1).squeeze()
    height = np.fromfile(f, np.int32, 1).squeeze()

    flow = np.fromfile(f, np.float32, width * height * 2).reshape((height, width, 2))

    return flow.astype(np.float32)

def readImage(name):
    if name.endswith('.pfm') or name.endswith('.PFM'):
        data = readPFM(name)[0]
        if len(data.shape)==3:
            return data[:,:,0:3]
        else:
            return data

    return misc.imread(name)

def writeImage(name, data):
    if name.endswith('.pfm') or name.endswith('.PFM'):
        return writePFM(name, data, 1)

    return misc.imsave(name, data)

def writeFlow(name, flow):
    f = open(name, 'wb')
    f.write('PIEH'.encode('utf-8'))
    np.array([flow.shape[1], flow.shape[0]], dtype=np.int32).tofile(f)
    flow = flow.astype(np.float32)
    flow.tofile(f)

def readFloat(name):
    f = open(name, 'rb')

    if(f.readline().decode("utf-8"))  != 'float\n':
        raise Exception('float file %s did not contain <float> keyword' % name)

    dim = int(f.readline())

    dims = []
    count = 1
    for i in range(0, dim):
        d = int(f.readline())
        dims.append(d)
        count *= d

    dims = list(reversed(dims))

    data = np.fromfile(f, np.float32, count).reshape(dims)
    if dim > 2:
        data = np.transpose(data, (2, 1, 0))
        data = np.transpose(data, (1, 0, 2))

    return data

def writeFloat(name, data):
    f = open(name, 'wb')

    dim=len(data.shape)
    if dim>3:
        raise Exception('bad float file dimension: %d' % dim)

    f.write(('float\n').encode('ascii'))
    f.write(('%d\n' % dim).encode('ascii'))

    if dim == 1:
        f.write(('%d\n' % data.shape[0]).encode('ascii'))
    else:
        f.write(('%d\n' % data.shape[1]).encode('ascii'))
        f.write(('%d\n' % data.shape[0]).encode('ascii'))
        for i in range(2, dim):
            f.write(('%d\n' % data.shape[i]).encode('ascii'))

    data = data.astype(np.float32)
    if dim==2:
        data.tofile(f)

    else:
        np.transpose(data, (2, 0, 1)).tofile(f)

# MIT License
#
# Copyright (c) 2018 Tom Runia
#
# 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 conditions.
#
# Author: Tom Runia
# Date Created: 2018-08-03




def make_colorwheel():
    '''
    Generates a color wheel for optical flow visualization as presented in:
        Baker et al. "A Database and Evaluation Methodology for Optical Flow" (ICCV, 2007)
        URL: http://vision.middlebury.edu/flow/flowEval-iccv07.pdf
    According to the C++ source code of Daniel Scharstein
    According to the Matlab source code of Deqing Sun
    '''

    RY = 15
    YG = 6
    GC = 4
    CB = 11
    BM = 13
    MR = 6

    ncols = RY + YG + GC + CB + BM + MR
    colorwheel = np.zeros((ncols, 3))
    col = 0

    # RY
    colorwheel[0:RY, 0] = 255
    colorwheel[0:RY, 1] = np.floor(255*np.arange(0,RY)/RY)
    col = col+RY
    # YG
    colorwheel[col:col+YG, 0] = 255 - np.floor(255*np.arange(0,YG)/YG)
    colorwheel[col:col+YG, 1] = 255
    col = col+YG
    # GC
    colorwheel[col:col+GC, 1] = 255
    colorwheel[col:col+GC, 2] = np.floor(255*np.arange(0,GC)/GC)
    col = col+GC
    # CB
    colorwheel[col:col+CB, 1] = 255 - np.floor(255*np.arange(CB)/CB)
    colorwheel[col:col+CB, 2] = 255
    col = col+CB
    # BM
    colorwheel[col:col+BM, 2] = 255
    colorwheel[col:col+BM, 0] = np.floor(255*np.arange(0,BM)/BM)
    col = col+BM
    # MR
    colorwheel[col:col+MR, 2] = 255 - np.floor(255*np.arange(MR)/MR)
    colorwheel[col:col+MR, 0] = 255
    return colorwheel


def flow_compute_color(u, v, convert_to_bgr=False):
    '''
    Applies the flow color wheel to (possibly clipped) flow components u and v.
    According to the C++ source code of Daniel Scharstein
    According to the Matlab source code of Deqing Sun
    :param u: np.ndarray, input horizontal flow
    :param v: np.ndarray, input vertical flow
    :param convert_to_bgr: bool, whether to change ordering and output BGR instead of RGB
    :return:
    '''

    flow_image = np.zeros((u.shape[0], u.shape[1], 3), np.uint8)

    colorwheel = make_colorwheel()  # shape [55x3]
    ncols = colorwheel.shape[0]

    rad = np.sqrt(np.square(u) + np.square(v))
    a = np.arctan2(-v, -u)/np.pi

    fk = (a+1) / 2*(ncols-1)
    k0 = np.floor(fk).astype(np.int32)
    k1 = k0 + 1
    k1[k1 == ncols] = 0
    f = fk - k0

    for i in range(colorwheel.shape[1]):

        tmp = colorwheel[:,i]
        col0 = tmp[k0] / 255.0
        col1 = tmp[k1] / 255.0
        col = (1-f)*col0 + f*col1

        idx = (rad <= 1)
        col[idx]  = 1 - rad[idx] * (1-col[idx])
        col[~idx] = col[~idx] * 0.75   # out of range?

        # Note the 2-i => BGR instead of RGB
        ch_idx = 2-i if convert_to_bgr else i
        flow_image[:,:,ch_idx] = np.floor(255 * col)

    return flow_image


def flow_to_color(flow_uv, clip_flow=None, convert_to_bgr=False):
    '''
    Expects a two dimensional flow image of shape [H,W,2]
    According to the C++ source code of Daniel Scharstein
    According to the Matlab source code of Deqing Sun
    :param flow_uv: np.ndarray of shape [H,W,2]
    :param clip_flow: float, maximum clipping value for flow
    :return:
    '''

    assert flow_uv.ndim == 3, 'input flow must have three dimensions'
    assert flow_uv.shape[2] == 2, 'input flow must have shape [H,W,2]'

    if clip_flow is not None:
        flow_uv = np.clip(flow_uv, 0, clip_flow)

    u = flow_uv[:,:,0]
    v = flow_uv[:,:,1]

    rad = np.sqrt(np.square(u) + np.square(v))
    rad_max = np.max(rad)

    epsilon = 1e-5
    u = u / (rad_max + epsilon)
    v = v / (rad_max + epsilon)

    return flow_compute_color(u, v, convert_to_bgr)