ppm.py

   1 # -*- coding: utf-8 -*-
   2 ####################################################
   3 # Copyright © 2009 Luxia SAS. All rights reserved. #
   4 #                                                  #
   5 # Contributors:                                    #
   6 #  - Benoît Pin <pinbe@luxia.fr>                   #
   7 ####################################################
   8 """ PPM File support module
   9
  10
  11
  12 """
  13
  14 from subprocess import Popen, PIPE
  15 from tempfile import TemporaryFile
  16 import os
  17 from math import ceil
  18 from PIL.Image import open as imgopen
  19 from PIL.Image import fromstring
  20 from PIL.Image import ANTIALIAS
  21 from cStringIO import StringIO
  22
  23 DGJPEG = 'djpeg'
  24 RESIZING_TILE_SIZE = 1024
  25
  26 class PPMFile(object) :
  27
  28         def __init__(self, f, tileSize=256, isRaw=False) :
  29                 # convert jpeg -> ppm with djpeg
  30                 if not isRaw :
  31                         # print 'djpeg'
  32                         self.fp = TemporaryFile(mode='w+')
  33                         p = Popen(DGJPEG, stdin=f, stdout=self.fp, stderr=PIPE, shell=True)
  34                         p.wait()
  35                         err = p.stderr.read()
  36                         if err :
  37                                 raise SystemError, err
  38                 else :
  39                         self.fp = f
  40
  41                 # get image specs with PIL
  42                 self.fp.seek(0)
  43                 im = imgopen(self.fp)
  44                 decoder, region, offset, parameters = im.tile[0]
  45                 x, y, width, height = region
  46                 del im
  47                 assert decoder == 'raw'
  48                 mode = parameters[0]
  49                 assert mode in ('RGB', 'L'), "Unsupported mode %s" % mode
  50
  51                 if mode == 'RGB' :
  52                         sampleSize = 3
  53                 elif mode == 'L' :
  54                         sampleSize = 1
  55
  56                 self.width = width
  57                 self.height = height
  58                 self.offset = offset
  59                 self.mode = parameters[0]
  60                 self.sampleSize = sampleSize
  61                 self._setTileSize(tileSize)
  62
  63         def _setTileSize(self, tileSize) :
  64                 self.tileSize = tileSize
  65                 self.tilesX = int(ceil(float(self.width) / self.tileSize))
  66                 self.tilesY = int(ceil(float(self.height) / self.tileSize))
  67
  68         def getTile(self, xt, yt) :
  69                 f = self.fp
  70                 ss = self.sampleSize
  71                 x = xt * self.tileSize
  72                 y = yt * self.tileSize
  73                 start = (self.width * y + x) * ss + self.offset
  74
  75                 tw = th = self.tileSize
  76
  77                 bw = self.width - x
  78                 if bw < self.tileSize  :
  79                         tw = bw
  80                 bh = self.height - y
  81                 if bh < self.tileSize :
  82                         th = bh
  83
  84                 assert tw > 0 and th > 0, "Tile requested out of image."
  85
  86                 size = (tw, th)
  87                 tll = tw * ss
  88                 jump = (self.width - tw) * ss
  89
  90                 f.seek(start)
  91                 data = StringIO()
  92
  93                 for line in xrange(size[1]) :
  94                         data.write(f.read(tll))
  95                         f.seek(jump, 1)
  96
  97                 data.seek(0)
  98                 im = fromstring(self.mode, size, data.read())
  99                 return im
 100
 101         def getTileSequence(self):
 102                 seq = []
 103                 for y in xrange(self.tilesY) :
 104                         for x in xrange(self.tilesX) :
 105                                 seq.append((x, y))
 106                 return seq
 107
 108         def resize(self, ratio=None, maxLength=None) :
 109                 if ratio and maxLength :
 110                         raise AttributeError("'ratio' and 'size' are mutually exclusive.")
 111                 if maxLength :
 112                         maxFullLength = max(self.width, self.height)
 113                         ratio = float(maxLength) / maxFullLength
 114
 115                 tileSizeBak = self.tileSize
 116
 117                 self._setTileSize(RESIZING_TILE_SIZE)
 118
 119                 width = height = 0
 120                 # cumul des arrondis
 121                 width = int(round(self.tileSize * ratio)) * (self.tilesX -1)
 122                 width += int(round((self.width - self.tileSize * (self.tilesX -1)) * ratio))
 123
 124                 height = int(round(self.tileSize * ratio)) * (self.tilesY -1)
 125                 height += int(round((self.height - self.tileSize * (self.tilesY -1)) * ratio))
 126
 127                 magic = self.mode == 'RGB' and 6 or 5
 128                 head = 'P%d %d %d 255\n' % (magic, width, height)
 129                 offset = len(head)
 130
 131                 out = TemporaryFile(mode='w+')
 132                 out.write(head)
 133
 134                 ss = self.sampleSize
 135                 rTll = int(round(self.tileSize * ratio))
 136
 137                 for x, y in self.getTileSequence() :
 138                         # print 'resize', (x,y)
 139                         tile = self.getTile(x,y)
 140                         tileSize = tile.size
 141                         size = map(lambda l : int(round(l * ratio)), tileSize)
 142
 143                         if size[0] and size[1] :
 144                                 resized = tile.resize(size, ANTIALIAS)
 145                                 data = resized.tostring()
 146
 147                                 start = (y * width + x) * ss * rTll + offset
 148                                 jump = (width - size[0]) * ss
 149
 150                                 out.seek(start)
 151                                 tll = size[0] * ss
 152
 153                                 # écriture dans le bon ordre (c'est quand même plus agréable à l'œil)
 154                                 for l in xrange(size[1]) :
 155                                         lineData = data[l*tll:(l+1)*tll]
 156                                         out.write(lineData)
 157                                         out.seek(jump, 1)
 158
 159                 out.seek(0,2)
 160                 length = out.tell()
 161                 assert length - len(head) == width * height * ss, (length - len(head), width * height * ss)
 162                 out.seek(0)
 163
 164                 self._setTileSize(tileSizeBak)
 165                 return PPMFile(out, tileSize=tileSizeBak, isRaw=True)
 166
 167         def getImage(self) :
 168                 self.fp.seek(0)
 169                 return imgopen(self.fp)
 170
 171         def __del__(self) :
 172                 self.fp.close()
 173
 174
 175 if __name__ == '__main__' :
 176         f = open('/Users/pinbe/Desktop/Chauve_souris.jpg')
 177         try :
 178                 ppm = PPMFile(f, tileSize=256)
 179                 rppm = ppm.resize(maxLength=800)
 180                 im = rppm.getImage()
 181                 im.show()
 182                 for x, y in ppm.getTileSequence() :
 183                         im = ppm.getTile(x, y)
 184                         im.save('testoutput/%d_%d.jpg' % (x, y), 'JPEG', quality=90)
 185         finally :
 186                 f.close()