Use constants

Author: radarhere

src/PIL/TiffImagePlugin.py

@@ -1153,7 +1153,7 @@ def getxmp(self):
 
         :returns: XMP tags in a dictionary.
         """
-        return self._getxmp(self.tag_v2[700]) if 700 in self.tag_v2 else {}
+        return self._getxmp(self.tag_v2[XMP]) if XMP in self.tag_v2 else {}
 
     def get_photoshop_blocks(self):
         """
@@ -1328,7 +1328,7 @@ def _setup(self):
         logger.debug(f"- photometric_interpretation: {photo}")
         logger.debug(f"- planar_configuration: {self._planar_configuration}")
         logger.debug(f"- fill_order: {fillorder}")
-        logger.debug(f"- YCbCr subsampling: {self.tag.get(530)}")
+        logger.debug(f"- YCbCr subsampling: {self.tag.get(YCBCRSUBSAMPLING)}")
 
         # size
         xsize = int(self.tag_v2.get(IMAGEWIDTH))
@@ -1469,8 +1469,8 @@ def _setup(self):
             else:
                 # tiled image
                 offsets = self.tag_v2[TILEOFFSETS]
-                w = self.tag_v2.get(322)
-                h = self.tag_v2.get(323)
+                w = self.tag_v2.get(TILEWIDTH)
+                h = self.tag_v2.get(TILELENGTH)
 
             for offset in offsets:
                 if x + w > xsize: