Merge pull request #5476 from radarhere/dpi_rounding

Tests/test_file_bmp.py

@@ -63,7 +63,7 @@ def test_dpi():
 
     output.seek(0)
     with Image.open(output) as reloaded:
-        assert reloaded.info["dpi"] == dpi
+        assert reloaded.info["dpi"] == (72.008961115161, 72.008961115161)
 
 
 def test_save_bmp_with_dpi(tmp_path):
@@ -71,6 +71,7 @@ def test_save_bmp_with_dpi(tmp_path):
     # Arrange
     outfile = str(tmp_path / "temp.jpg")
     with Image.open("Tests/images/hopper.bmp") as im:
+        assert im.info["dpi"] == (95.98654816726399, 95.98654816726399)
 
         # Act
         im.save(outfile, "JPEG", dpi=im.info["dpi"])
@@ -78,31 +79,17 @@ def test_save_bmp_with_dpi(tmp_path):
         # Assert
         with Image.open(outfile) as reloaded:
             reloaded.load()
-            assert im.info["dpi"] == reloaded.info["dpi"]
+            assert reloaded.info["dpi"] == (96, 96)
-            assert im.size == reloaded.size
+            assert reloaded.size == im.size
             assert reloaded.format == "JPEG"
 
 
-def test_load_dpi_rounding():
+def test_save_float_dpi(tmp_path):
-    # Round up
-    with Image.open("Tests/images/hopper.bmp") as im:
-        assert im.info["dpi"] == (96, 96)
-
-    # Round down
-    with Image.open("Tests/images/hopper_roundDown.bmp") as im:
-        assert im.info["dpi"] == (72, 72)
-
-
-def test_save_dpi_rounding(tmp_path):
     outfile = str(tmp_path / "temp.bmp")
     with Image.open("Tests/images/hopper.bmp") as im:
-        im.save(outfile, dpi=(72.2, 72.2))
+        im.save(outfile, dpi=(72.21216100543306, 72.21216100543306))
         with Image.open(outfile) as reloaded:
-            assert reloaded.info["dpi"] == (72, 72)
+            assert reloaded.info["dpi"] == (72.21216100543306, 72.21216100543306)
-
-        im.save(outfile, dpi=(72.8, 72.8))
-    with Image.open(outfile) as reloaded:
-        assert reloaded.info["dpi"] == (73, 73)
 
 
 def test_load_dib():

Tests/test_file_jpeg.py

@@ -656,15 +656,6 @@ class TestFileJpeg:
                 reloaded.load()
                 assert im.info["dpi"] == reloaded.info["dpi"]
 
-    def test_load_dpi_rounding(self):
-        # Round up
-        with Image.open("Tests/images/iptc_roundUp.jpg") as im:
-            assert im.info["dpi"] == (44, 44)
-
-        # Round down
-        with Image.open("Tests/images/iptc_roundDown.jpg") as im:
-            assert im.info["dpi"] == (2, 2)
-
     def test_save_dpi_rounding(self, tmp_path):
         outfile = str(tmp_path / "temp.jpg")
         with Image.open("Tests/images/hopper.jpg") as im:

Tests/test_file_png.py

@@ -386,25 +386,12 @@ class TestFilePng:
         # Check dpi roundtripping
 
         with Image.open(TEST_PNG_FILE) as im:
-            im = roundtrip(im, dpi=(100, 100))
+            im = roundtrip(im, dpi=(100.33, 100.33))
-        assert im.info["dpi"] == (100, 100)
+        assert im.info["dpi"] == (100.33, 100.33)
 
-    def test_load_dpi_rounding(self):
+    def test_load_float_dpi(self):
-        # Round up
         with Image.open(TEST_PNG_FILE) as im:
-            assert im.info["dpi"] == (96, 96)
+            assert im.info["dpi"] == (95.9866, 95.9866)
-
-        # Round down
-        with Image.open("Tests/images/icc_profile_none.png") as im:
-            assert im.info["dpi"] == (72, 72)
-
-    def test_save_dpi_rounding(self):
-        with Image.open(TEST_PNG_FILE) as im:
-            im = roundtrip(im, dpi=(72.2, 72.2))
-        assert im.info["dpi"] == (72, 72)
-
-        im = roundtrip(im, dpi=(72.8, 72.8))
-        assert im.info["dpi"] == (73, 73)
 
     def test_roundtrip_text(self):
         # Check text roundtripping

src/PIL/BmpImagePlugin.py

@@ -115,9 +115,7 @@ class BmpImageFile(ImageFile.ImageFile):
             )
             file_info["colors"] = i32(header_data, 28)
             file_info["palette_padding"] = 4
-            self.info["dpi"] = tuple(
+            self.info["dpi"] = tuple(x / 39.3701 for x in file_info["pixels_per_meter"])
-                int(x / 39.3701 + 0.5) for x in file_info["pixels_per_meter"]
-            )
             if file_info["compression"] == self.BITFIELDS:
                 if len(header_data) >= 52:
                     for idx, mask in enumerate(

src/PIL/JpegImagePlugin.py

@@ -33,6 +33,7 @@
 #
 import array
 import io
+import math
 import os
 import struct
 import subprocess
@@ -162,15 +163,17 @@ def APP(self, marker):
                 dpi = float(x_resolution[0]) / x_resolution[1]
             except TypeError:
                 dpi = x_resolution
+            if math.isnan(dpi):
+                raise ValueError
             if resolution_unit == 3:  # cm
                 # 1 dpcm = 2.54 dpi
                 dpi *= 2.54
-            self.info["dpi"] = int(dpi + 0.5), int(dpi + 0.5)
+            self.info["dpi"] = dpi, dpi
         except (KeyError, SyntaxError, ValueError, ZeroDivisionError):
             # SyntaxError for invalid/unreadable EXIF
             # KeyError for dpi not included
             # ZeroDivisionError for invalid dpi rational value
-            # ValueError for x_resolution[0] being an invalid float
+            # ValueError for dpi being an invalid float
             self.info["dpi"] = 72, 72
 
 

src/PIL/PngImagePlugin.py

@@ -500,7 +500,7 @@ class PngStream(ChunkStream):
         px, py = i32(s, 0), i32(s, 4)
         unit = s[8]
         if unit == 1:  # meter
-            dpi = int(px * 0.0254 + 0.5), int(py * 0.0254 + 0.5)
+            dpi = px * 0.0254, py * 0.0254
             self.im_info["dpi"] = dpi
         elif unit == 0:
             self.im_info["aspect"] = px, py