Added reading of TIFF child images

Author: radarhere

Tests/images/child_ifd.tiff

@@ -84,6 +84,23 @@ def test_context_manager(self):
             with Image.open("Tests/images/multipage.tiff") as im:
                 im.load()
 
+    def test_get_child_images(self):
+        def check(ims, sizes):
+            assert len(ims) == len(sizes)
+
+            for i, im in enumerate(ims):
+                w = sizes[i]
+                expected = Image.new("RGB", (w, w), "#f00")
+                assert_image_similar(im, expected, 1)
+
+        with Image.open("Tests/images/child_ifd.tiff") as im:
+            ims = im.get_child_images()
+        check(ims, (16, 8))
+
+        with Image.open("Tests/images/child_ifd_jpeg.tiff") as im:
+            ims = im.get_child_images()
+        check(ims, (20,))
+
     def test_mac_tiff(self):
         # Read RGBa images from macOS [@PIL136]
 

Tests/images/child_ifd_jpeg.tiff

@@ -1148,6 +1148,39 @@ def tell(self):
         """Return the current frame number"""
         return self.__frame
 
+    def get_child_images(self):
+        if SUBIFD not in self.tag_v2:
+            return []
+        child_images = []
+        exif = self.getexif()
+        offset = None
+        for im_offset in self.tag_v2[SUBIFD]:
+            # reset buffered io handle in case fp
+            # was passed to libtiff, invalidating the buffer
+            current_offset = self._fp.tell()
+            if offset is None:
+                offset = current_offset
+
+            fp = self._fp
+            ifd = exif._get_ifd_dict(im_offset)
+            jpegInterchangeFormat = ifd.get(513)
+            if jpegInterchangeFormat is not None:
+                fp.seek(jpegInterchangeFormat)
+                jpeg_data = fp.read(ifd.get(514))
+
+                fp = io.BytesIO(jpeg_data)
+
+            with Image.open(fp) as im:
+                if jpegInterchangeFormat is None:
+                    im._frame_pos = [im_offset]
+                    im._seek(0)
+                im.load()
+                child_images.append(im)
+
+        if offset is not None:
+            self._fp.seek(offset)
+        return child_images
+
     def getxmp(self):
         """
         Returns a dictionary containing the XMP tags.

Tests/test_file_tiff.py

@@ -160,6 +160,7 @@ def lookup(tag, group=None):
     323: ("TileLength", LONG, 1),
     324: ("TileOffsets", LONG, 0),
     325: ("TileByteCounts", LONG, 0),
+    330: ("SubIFDs", LONG, 0),
     332: ("InkSet", SHORT, 1),
     333: ("InkNames", ASCII, 1),
     334: ("NumberOfInks", SHORT, 1),