DPI information not transferred automatically from PNG to JPEG

ocrmypdf/main.py

@@ -670,7 +670,8 @@ def select_image_for_pdf(
     pageinfo = get_pageinfo(image, pdfinfo, pdfinfo_lock)
     if all(image['enc'] == 'jpeg' for image in pageinfo['images']):
         # If all images were JPEGs originally, produce a JPEG as output
-        Image.open(image).save(output_file, format='JPEG')
+        im = Image.open(image)
+        im.save(output_file, format='JPEG', dpi=im.info['dpi'])
     else:
         re_symlink(image, output_file)
 

tests/test_main.py

@@ -202,14 +202,14 @@ def test_override_metadata(spoof_tesseract_noop):
     ])
 def test_oversample(spoof_tesseract_cache, renderer):
     oversampled_pdf = check_ocrmypdf(
-        'skew.pdf', 'test_oversample_%s.pdf' % renderer, '--oversample', '300',
+        'skew.pdf', 'test_oversample_%s.pdf' % renderer, '--oversample', '350',
         '-f',
         '--pdf-renderer', renderer, env=spoof_tesseract_cache)
 
     pdfinfo = pdf_get_all_pageinfo(oversampled_pdf)
 
     print(pdfinfo[0]['xres'])
-    assert abs(pdfinfo[0]['xres'] - 300) < 1
+    assert abs(pdfinfo[0]['xres'] - 350) < 1
 
 
 def test_repeat_ocr():