Merge pull request #3674 from radarhere/png_exif

Added EXIF support for PNG

Tests/test_file_png.py

@@ -590,6 +590,40 @@ class TestFilePng(PillowTestCase):
         im = Image.open("Tests/images/hopper_idat_after_image_end.png")
         self.assertEqual(im.text, {'TXT': 'VALUE', 'ZIP': 'VALUE'})
 
+    def test_exif(self):
+        im = Image.open("Tests/images/exif.png")
+        exif = im._getexif()
+        self.assertEqual(exif[274], 1)
+
+    def test_exif_save(self):
+        im = Image.open("Tests/images/exif.png")
+
+        test_file = self.tempfile("temp.png")
+        im.save(test_file)
+
+        reloaded = Image.open(test_file)
+        exif = reloaded._getexif()
+        self.assertEqual(exif[274], 1)
+
+    def test_exif_from_jpg(self):
+        im = Image.open("Tests/images/pil_sample_rgb.jpg")
+
+        test_file = self.tempfile("temp.png")
+        im.save(test_file)
+
+        reloaded = Image.open(test_file)
+        exif = reloaded._getexif()
+        self.assertEqual(exif[305], "Adobe Photoshop CS Macintosh")
+
+    def test_exif_argument(self):
+        im = Image.open(TEST_PNG_FILE)
+
+        test_file = self.tempfile("temp.png")
+        im.save(test_file, exif=b"exifstring")
+
+        reloaded = Image.open(test_file)
+        self.assertEqual(reloaded.info["exif"], b"Exif\x00\x00exifstring")
+
     @unittest.skipUnless(HAVE_WEBP and _webp.HAVE_WEBPANIM,
                          "WebP support not installed with animation")
     def test_apng(self):

docs/handbook/image-file-formats.rst

@@ -462,6 +462,10 @@ PNG
 Pillow identifies, reads, and writes PNG files containing ``1``, ``L``, ``P``,
 ``RGB``, or ``RGBA`` data. Interlaced files are supported as of v1.1.7.
 
+As of Pillow 6.0, EXIF data can be read from PNG images. However, unlike other
+image formats, EXIF data is not guaranteed to have been read until
+:py:meth:`~PIL.Image.Image.load` has been called.
+
 The :py:meth:`~PIL.Image.Image.open` method sets the following
 :py:attr:`~PIL.Image.Image.info` properties, when appropriate:
 
@@ -527,6 +531,11 @@ The :py:meth:`~PIL.Image.Image.save` method supports the following options:
 **icc_profile**
     The ICC Profile to include in the saved file.
 
+**exif**
+    The exif data to include in the saved file.
+
+    .. versionadded:: 6.0.0
+
 **bits (experimental)**
     For ``P`` images, this option controls how many bits to store. If omitted,
     the PNG writer uses 8 bits (256 colors).

docs/releasenotes/6.0.0.rst

@@ -112,6 +112,13 @@ Image.quantize
 
 The `dither` option is now a customisable parameter (was previously hardcoded to `1`). This parameter takes the same values used in `Image.convert`
 
+PNG EXIF Data
+^^^^^^^^^^^^^
+
+EXIF data can now be read from and saved to PNG images. However, unlike other image
+formats, EXIF data is not guaranteed to have been read until
+:py:meth:`~PIL.Image.Image.load` has been called.
+
 Other Changes
 =============
 

src/PIL/PngImagePlugin.py

@@ -529,6 +529,11 @@ class PngStream(ChunkStream):
 
         return s
 
+    def chunk_eXIf(self, pos, length):
+        s = ImageFile._safe_read(self.fp, length)
+        self.im_info["exif"] = b"Exif\x00\x00"+s
+        return s
+
     # APNG chunks
     def chunk_acTL(self, pos, length):
         s = ImageFile._safe_read(self.fp, length)
@@ -683,6 +688,12 @@ class PngImageFile(ImageFile.ImageFile):
         self.png.close()
         self.png = None
 
+    def _getexif(self):
+        if "exif" not in self.info:
+            self.load()
+        from .JpegImagePlugin import _getexif
+        return _getexif(self)
+
 
 # --------------------------------------------------------------------
 # PNG writer
@@ -861,6 +872,12 @@ def _save(im, fp, filename, chunk=putchunk):
                 chunks.remove(cid)
                 chunk(fp, cid, data)
 
+    exif = im.encoderinfo.get("exif", im.info.get("exif"))
+    if exif:
+        if exif.startswith(b"Exif\x00\x00"):
+            exif = exif[6:]
+        chunk(fp, b"eXIf", exif)
+
     ImageFile._save(im, _idat(fp, chunk),
                     [("zip", (0, 0)+im.size, 0, rawmode)])