ppm.py

   1 # -*- coding: utf-8 -*-
   2 #######################################################################################
   3 #   Plinn - http://plinn.org                                                          #
   4 #   Copyright © 2009  Benoît Pin <pin@cri.ensmp.fr>                                   #
   5 #                                                                                     #
   6 #   This program is free software; you can redistribute it and/or                     #
   7 #   modify it under the terms of the GNU General Public License                       #
   8 #   as published by the Free Software Foundation; either version 2                    #
   9 #   of the License, or (at your option) any later version.                            #
  10 #                                                                                     #
  11 #   This program is distributed in the hope that it will be useful,                   #
  12 #   but WITHOUT ANY WARRANTY; without even the implied warranty of                    #
  13 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                     #
  14 #   GNU General Public License for more details.                                      #
  15 #                                                                                     #
  16 #   You should have received a copy of the GNU General Public License                 #
  17 #   along with this program; if not, write to the Free Software                       #
  18 #   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.   #
  19 #######################################################################################
  20 """ PPM File support module
  21
  22
  23
  24 """
  25
  26 from subprocess import Popen, PIPE
  27 from tempfile import TemporaryFile
  28 import os
  29 from math import ceil
  30 from PIL.Image import open as imgopen
  31 from PIL.Image import fromstring
  32 from PIL.Image import ANTIALIAS
  33 from cStringIO import StringIO
  34
  35 DGJPEG = 'djpeg'
  36 RESIZING_TILE_SIZE = 1024
  37
  38 class PPMFile(object) :
  39
  40         def __init__(self, f, tileSize=256, isRaw=False) :
  41                 # convert jpeg -> ppm with djpeg
  42                 if not isRaw :
  43                         # print 'djpeg'
  44                         self.fp = TemporaryFile(mode='w+')
  45                         p = Popen(DGJPEG, stdin=f, stdout=self.fp, stderr=PIPE, shell=True)
  46                         p.wait()
  47                         err = p.stderr.read()
  48                         if err :
  49                                 raise SystemError, err
  50                 else :
  51                         self.fp = f
  52
  53                 # get image specs with PIL
  54                 self.fp.seek(0)
  55                 im = imgopen(self.fp)
  56                 decoder, region, offset, parameters = im.tile[0]
  57                 x, y, width, height = region
  58                 del im
  59                 assert decoder == 'raw'
  60                 mode = parameters[0]
  61                 assert mode in ('RGB', 'L'), "Unsupported mode %s" % mode
  62
  63                 if mode == 'RGB' :
  64                         sampleSize = 3
  65                 elif mode == 'L' :
  66                         sampleSize = 1
  67
  68                 self.width = width
  69                 self.height = height
  70                 self.offset = offset
  71                 self.mode = parameters[0]
  72                 self.sampleSize = sampleSize
  73                 self._setTileSize(tileSize)
  74
  75         def _setTileSize(self, tileSize) :
  76                 self.tileSize = tileSize
  77                 self.tilesX = int(ceil(float(self.width) / self.tileSize))
  78                 self.tilesY = int(ceil(float(self.height) / self.tileSize))
  79
  80         def getTile(self, xt, yt) :
  81                 f = self.fp
  82                 ss = self.sampleSize
  83                 x = xt * self.tileSize
  84                 y = yt * self.tileSize
  85                 start = (self.width * y + x) * ss + self.offset
  86
  87                 tw = th = self.tileSize
  88
  89                 bw = self.width - x
  90                 if bw < self.tileSize  :
  91                         tw = bw
  92                 bh = self.height - y
  93                 if bh < self.tileSize :
  94                         th = bh
  95
  96                 assert tw > 0 and th > 0, "Tile requested out of image."
  97
  98                 size = (tw, th)
  99                 tll = tw * ss
 100                 jump = (self.width - tw) * ss
 101
 102                 f.seek(start)
 103                 data = StringIO()
 104
 105                 for line in xrange(size[1]) :
 106                         data.write(f.read(tll))
 107                         f.seek(jump, 1)
 108
 109                 data.seek(0)
 110                 im = fromstring(self.mode, size, data.read())
 111                 return im
 112
 113         def getTileSequence(self):
 114                 seq = []
 115                 for y in xrange(self.tilesY) :
 116                         for x in xrange(self.tilesX) :
 117                                 seq.append((x, y))
 118                 return seq
 119
 120         def resize(self, ratio=None, maxLength=None) :
 121                 if ratio and maxLength :
 122                         raise AttributeError("'ratio' and 'size' are mutually exclusive.")
 123                 if maxLength :
 124                         maxFullLength = max(self.width, self.height)
 125                         ratio = float(maxLength) / maxFullLength
 126
 127                 tileSizeBak = self.tileSize
 128
 129                 self._setTileSize(RESIZING_TILE_SIZE)
 130
 131                 width = height = 0
 132                 # cumul des arrondis
 133                 width = int(round(self.tileSize * ratio)) * (self.tilesX -1)
 134                 width += int(round((self.width - self.tileSize * (self.tilesX -1)) * ratio))
 135
 136                 height = int(round(self.tileSize * ratio)) * (self.tilesY -1)
 137                 height += int(round((self.height - self.tileSize * (self.tilesY -1)) * ratio))
 138
 139                 magic = self.mode == 'RGB' and 6 or 5
 140                 head = 'P%d %d %d 255\n' % (magic, width, height)
 141                 offset = len(head)
 142
 143                 out = TemporaryFile(mode='w+')
 144                 out.write(head)
 145
 146                 ss = self.sampleSize
 147                 rTll = int(round(self.tileSize * ratio))
 148
 149                 for x, y in self.getTileSequence() :
 150                         # print 'resize', (x,y)
 151                         tile = self.getTile(x,y)
 152                         tileSize = tile.size
 153                         size = map(lambda l : int(round(l * ratio)), tileSize)
 154
 155                         if size[0] and size[1] :
 156                                 resized = tile.resize(size, ANTIALIAS)
 157                                 data = resized.tostring()
 158
 159                                 start = (y * width + x) * ss * rTll + offset
 160                                 jump = (width - size[0]) * ss
 161
 162                                 out.seek(start)
 163                                 tll = size[0] * ss
 164
 165                                 # écriture dans le bon ordre (c'est quand même plus agréable à l'œil)
 166                                 for l in xrange(size[1]) :
 167                                         lineData = data[l*tll:(l+1)*tll]
 168                                         out.write(lineData)
 169                                         out.seek(jump, 1)
 170
 171                 out.seek(0,2)
 172                 length = out.tell()
 173                 assert length - len(head) == width * height * ss, (length - len(head), width * height * ss)
 174                 out.seek(0)
 175
 176                 self._setTileSize(tileSizeBak)
 177                 return PPMFile(out, tileSize=tileSizeBak, isRaw=True)
 178
 179         def getImage(self) :
 180                 self.fp.seek(0)
 181                 return imgopen(self.fp)
 182
 183         def __del__(self) :
 184                 self.fp.close()
 185
 186
 187 if __name__ == '__main__' :
 188         f = open('/Users/pinbe/Desktop/Chauve_souris.jpg')
 189         try :
 190                 ppm = PPMFile(f, tileSize=256)
 191                 rppm = ppm.resize(maxLength=800)
 192                 im = rppm.getImage()
 193                 im.show()
 194                 for x, y in ppm.getTileSequence() :
 195                         im = ppm.getTile(x, y)
 196                         im.save('testoutput/%d_%d.jpg' % (x, y), 'JPEG', quality=90)
 197         finally :
 198                 f.close()