Fixed BestPix to always return the highest resolution available, even…

… if a lower bit depth than the original

ccmain/tesseractclass.h

@@ -206,14 +206,22 @@ class Tesseract : public Wordrec {
       sub_langs_[i]->set_pix_original(original_pix ? pixClone(original_pix)
                                                    : nullptr);
   }
-  // Returns a pointer to a Pix representing the best available (original) image
-  // of the page. Can be of any bit depth, but never color-mapped, as that has
-  // always been dealt with. Note that in grey and color, 0 is black and 255 is
+  // Returns a pointer to a Pix representing the best available resolution image
+  // of the page, with best available bit depth as second priority. Result can
+  // be of any bit depth, but never color-mapped, as that has always been
+  // removed. Note that in grey and color, 0 is black and 255 is
   // white. If the input was binary, then black is 1 and white is 0.
   // To tell the difference pixGetDepth() will return 32, 8 or 1.
   // In any case, the return value is a borrowed Pix, and should not be
   // deleted or pixDestroyed.
-  Pix* BestPix() const { return pix_original_; }
+  Pix* BestPix() const {
+    if (pixGetWidth(pix_original_) == ImageWidth())
+      return pix_original_;
+    else if (pix_grey_ != NULL)
+      return pix_grey_;
+    else
+      return pix_binary_;
+  }
   void set_pix_thresholds(Pix* thresholds) {
     pixDestroy(&pix_thresholds_);
     pix_thresholds_ = thresholds;