From 7b72ffec4f8ed1243c222fe83a16a679e8fb3a79 Mon Sep 17 00:00:00 2001
From: "James R. Barlow" <jim@purplerock.ca>
Date: Fri, 29 Jul 2016 14:38:07 -0700
Subject: [PATCH] ocrmyimage: better handling of missing/invalid DPI

---
 ocrmypdf/main.py | 44 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/ocrmypdf/main.py b/ocrmypdf/main.py
index b3b9b474..ab64b9f5 100755
--- a/ocrmypdf/main.py
+++ b/ocrmypdf/main.py
@@ -401,19 +401,49 @@ def triage(
             if signature == b'%PDF':
                 re_symlink(input_file, output_file)
                 return
-    except EnvironmentError as e:
-        log.error(e)
-        sys.exit(ExitCode.input_file)
 
-    # We opened the file, but it's not a PDF
-    try:
+            # We opened the file, but it's not a PDF
+            f.seek(0)
+
+            log.info("Input file is not a PDF, checking if it is an image...")
+            im = Image.open(f)
+            f = None  # Image.load() closes the file handle
+            log.info("Input file is an image")
+
+            if 'dpi' in im.info:
+                if im.info['dpi'] <= (96, 96) and not options.oversample:
+                    log.info("Image size: (%d, %d)" % im.size)
+                    log.info("Image resolution: (%d, %d)" % im.info['dpi'])
+                    log.error(
+                        "Input file is an image, but the resolution (DPI) is "
+                        "not credible.  Estimate the resolution at which the "
+                        "image was scanned and specify it using --oversample.")
+                    sys.exit(ExitCode.input_file)
+            elif not options.oversample:
+                log.info("Image size: (%d, %d)" % im.size)
+                log.error(
+                    "Input file is an image, but has no resolution (DPI) "
+                    "in its metadata.  Estimate the resolution at which "
+                    "image was scanned and specify it using --oversample.")
+                sys.exit(ExitCode.input_file)
+            im.close()
+
+        log.info("Image seems valid. Try converting to PDF...")
+        layout_fun = None
+        if options.oversample:
+            layout_fun = img2pdf.get_fixed_dpi_layout_fun(
+                (options.oversample, options.oversample))
         with open(output_file, 'wb') as outf:
-            log.info("Input file is not a PDF, try converting it to PDF...")
             img2pdf.convert(
                 input_file,
+                layout_fun=layout_fun,
                 with_pdfrw=False,
                 outputstream=outf)
-    except OSError as e:
+        log.info("Successfully converted to PDF, processing...")
+    except img2pdf.ImageOpenError as e:
+        log.error(e)
+        sys.exit(ExitCode.input_file)
+    except EnvironmentError as e:
         log.error(e)
         sys.exit(ExitCode.input_file)