added CCITTFaxFilter support and a very crude image extraction.

pdfminer/image.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python2
+import sys
+import struct
+import os.path
+from pdftypes import LITERALS_DCT_DECODE
+from pdfcolor import LITERAL_DEVICE_GRAY, LITERAL_DEVICE_RGB
+
+def align32(x):
+    return ((x+3)/4)*4
+
+##  BMPWriter
+##
+class BMPWriter(object):
+
+    def __init__(self, fp, bits, width, height):
+        self.fp = fp
+        self.bits = bits
+        self.width = width
+        self.height = height
+        if bits == 1:
+            ncols = 2
+        elif bits == 8:
+            ncols = 256
+        elif bits == 24:
+            ncols = 0
+        else:
+            raise ValueError(bits)
+        self.linesize = align32((self.width*self.bits+7)/8)
+        self.datasize = self.linesize * self.height
+        info = struct.pack('<IiiHHIIIIII', 40, self.width, self.height, 1, self.bits, 0, self.datasize, 0, 0, 0, 0)
+        assert len(info) == 40, len(info)
+        header = struct.pack('<ccIHHI', 'B', 'M', 14+40+self.datasize, 0, 0, 14+40)
+        assert len(header) == 14, len(header)
+        self.fp.write(header)
+        self.fp.write(info)
+        if ncols == 2:
+            self.fp.write('\x00\x00\x00\xff\xff\xff')
+        elif ncols == 256:
+            for i in xrange(256):
+                self.fp.write(struct.pack('bbb', i,i,i))
+        self.pos0 = self.fp.tell()
+        self.pos1 = self.pos0 + self.datasize
+        return
+
+    def write_line(self, y, data):
+        self.fp.seek(self.pos1 - (y+1)*self.linesize)
+        self.fp.write(data)
+        return
+
+
+##  ImageWriter
+##
+class ImageWriter(object):
+
+    def __init__(self, outdir):
+        self.outdir = outdir
+        return
+
+    def export_image(self, image):
+        stream = image.stream
+        filters = stream.get_filters()
+        (width, height) = image.srcsize
+        if len(filters) == 1 and filters[0] in LITERALS_DCT_DECODE:
+            ext = '.jpg'
+        elif (image.bits == 1 or 
+              image.bits == 8 and image.colorspace in (LITERAL_DEVICE_RGB, LITERAL_DEVICE_GRAY)):
+            ext = '.%dx%d.bmp' % (width, height)
+        else:
+            ext = '.%d.%dx%d.img' % (image.bits, width, height)
+        name = image.name+ext
+        path = os.path.join(self.outdir, name)
+        fp = file(path, 'wb')
+        if ext == '.jpg':
+            fp.write(stream.get_rawdata())
+        elif image.bits == 1:
+            bmp = BMPWriter(fp, 1, width, height)
+            data = stream.get_data()
+            i = 0
+            width = (width+7)/8
+            for y in xrange(height):
+                bmp.write_line(y, data[i:i+width])
+                i += width
+        elif image.bits == 8 and image.colorspace is LITERAL_DEVICE_RGB:
+            bmp = BMPWriter(fp, 24, width, height)
+            data = stream.get_data()
+            i = 0
+            width = width*3
+            for y in xrange(height):
+                bmp.write_line(y, data[i:i+width])
+                i += width
+        elif image.bits == 8 and image.colorspace is LITERAL_DEVICE_GRAY:
+            bmp = BMPWriter(fp, 8, width, height)
+            data = stream.get_data()
+            i = 0
+            for y in xrange(height):
+                bmp.write_line(y, data[i:i+width])
+                i += width
+        else:
+            fp.write(stream.get_data())
+        fp.close()
+        return name