diff --git a/src/Text/Pandoc/ImageSize.hs b/src/Text/Pandoc/ImageSize.hs
index 09d9836a6..c640edfa4 100644
--- a/src/Text/Pandoc/ImageSize.hs
+++ b/src/Text/Pandoc/ImageSize.hs
@@ -161,7 +161,11 @@ findSvgTag img = case B.elemIndex '<' img of
 imageSize :: WriterOptions -> ByteString -> Either T.Text ImageSize
 imageSize opts img = checkDpi <$>
   case imageType img of
-       Just Png  -> getSize img
+       Just Png  -> case pngSize img of
+                      Just sz -> Right sz
+                      -- fall back to the full decoder if the header
+                      -- scan fails:
+                      Nothing -> getSize img
        Just Gif  -> getSize img
        Just Jpeg -> case jpegSize img of
                       Just sz -> Right sz
@@ -388,6 +392,53 @@ safeDecompress bs = fmap B.concat $
     (Zlib.decompressST Zlib.zlibFormat Zlib.defaultDecompressParams)
     (BL.fromStrict bs)
 
+-- | Extract PNG size from the IHDR and pHYs chunks, without
+-- decoding any image data.  (For paletted PNGs, JuicyPixels decodes
+-- the whole image before returning metadata.)
+pngSize :: ByteString -> Maybe ImageSize
+pngSize img =
+  case runGetOrFail pPngSize (BL.fromStrict img) of
+    Left _ -> Nothing
+    Right (_, _, sz) -> Just sz
+ where
+  pPngSize = do
+    skip 8  -- signature
+    -- the IHDR chunk always comes first:
+    ihdrLen <- getWord32be
+    ihdr <- getByteString 4
+    when (ihdr /= "IHDR" || ihdrLen < 13) $ fail "IHDR chunk not found"
+    w <- getWord32be
+    h <- getWord32be
+    skip (fromIntegral ihdrLen - 8 + 4)  -- rest of chunk and CRC
+    (dx, dy) <- findPhys
+    return ImageSize{ pxX = toInteger w, pxY = toInteger h
+                    , dpiX = dx, dpiY = dy }
+  -- scan the following chunks for pHYs:
+  findPhys = do
+    done <- isEmpty
+    if done
+       then return (72, 72)
+       else do
+         len <- getWord32be
+         typ <- getByteString 4
+         case typ of
+           "pHYs" -> do
+             ppuX <- getWord32be
+             ppuY <- getWord32be
+             unit <- getWord8
+             return $ if unit == 1  -- pixels per meter
+                         then (dpmToDpi (toInteger ppuX),
+                               dpmToDpi (toInteger ppuY))
+                         else (72, 72)
+           "IDAT" -> return (72, 72)  -- pHYs must precede image data
+           "IEND" -> return (72, 72)
+           _ -> skip (fromIntegral len + 4) *> findPhys
+
+-- | Convert dots per meter to dots per inch, using the same integer
+-- arithmetic as JuicyPixels for consistency.
+dpmToDpi :: Integer -> Integer
+dpmToDpi z = z * 254 `div` 10000
+
 -- | Extract JPEG size from the header, without decoding any image
 -- data.  Scans the marker segments preceding the entropy-coded data
 -- for a start-of-frame marker (which gives the dimensions in pixels)
diff --git a/test/Tests/ImageSize.hs b/test/Tests/ImageSize.hs
index 16ffbb307..06a488a29 100644
--- a/test/Tests/ImageSize.hs
+++ b/test/Tests/ImageSize.hs
@@ -52,6 +52,23 @@ jpegBare, jpegApp0 :: B.ByteString
 jpegBare = B.pack [0xff, 0xd8, 0xff, 0xdb] <> "rest"
 jpegApp0 = B.pack [0xff, 0xd8, 0xff, 0xe0] <> "rest"
 
+-- | A PNG chunk with the given type and body (and a dummy CRC).
+pngChunk :: B.ByteString -> B.ByteString -> B.ByteString
+pngChunk name body = be32 (B.length body) <> name <> body <> B.replicate 4 0
+
+-- | A PNG header with the given extra chunks after IHDR (and no
+-- image data).
+pngFile :: [B.ByteString] -> Int -> Int -> B.ByteString
+pngFile chunks w h = B.concat $
+  [ "\x89PNG\r\n\x1a\n"
+  , pngChunk "IHDR" (be32 w <> be32 h <> B.pack [8, 3, 0, 0, 0]) ]
+  <> chunks
+
+-- | A pHYs chunk with the given unit (1 = pixels per meter) and
+-- pixel densities.
+physChunk :: Word8 -> Int -> Int -> B.ByteString
+physChunk unit x y = pngChunk "pHYs" (be32 x <> be32 y <> B.pack [unit])
+
 -- | A JPEG marker segment with the given marker and body.
 jpegSeg :: Word8 -> B.ByteString -> B.ByteString
 jpegSeg m body = B.pack [0xff, m] <> be16 (B.length body + 2) <> body
@@ -227,6 +244,22 @@ tests =
       , testCase "tkhd box" $
           imageSize def avisTkhd @?= Right (ImageSize 640 480 72 72)
       ]
+    , testGroup "png"  -- headers without image data, so these only
+                       -- succeed if no decoding is attempted
+      [ testCase "no pHYs chunk" $
+          imageSize def (pngFile [] 640 480)
+            @?= Right (ImageSize 640 480 72 72)
+      , testCase "pHYs in pixels per meter" $
+          imageSize def (pngFile [physChunk 1 3937 3937] 640 480)
+            @?= Right (ImageSize 640 480 99 99)
+      , testCase "pHYs with unknown unit" $
+          imageSize def (pngFile [physChunk 0 4 3] 640 480)
+            @?= Right (ImageSize 640 480 72 72)
+      , testCase "pHYs after another chunk" $
+          imageSize def (pngFile [ pngChunk "tEXt" "k\0v"
+                                 , physChunk 1 3937 3937 ] 640 480)
+            @?= Right (ImageSize 640 480 99 99)
+      ]
     , testGroup "jpeg"  -- headers without image data, so these only
                         -- succeed if no decoding is attempted
       [ testCase "jfif dpi" $