avoid spurious error msg if no image in pdf

src/ocrPage.sh

@@ -66,13 +66,13 @@ getImgInfo() {
 	# so we will have to extract it again later using pdftoppm
 	pdfimages -f $page -l $page -j "$FILE_INPUT_PDF" "$curOrigImg" 1>&2	
 	# count number of extracted images
-	nbImg=`ls -1 "$curOrigImg"* | wc -l`
+	nbImg=`ls -1 "$curOrigImg"* 2>/dev/null | wc -l`
 	if [ $nbImg -ne "1" ]; then
 		[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: Expecting exactly 1 image covering the whole page (found $nbImg). Cannot compute dpi value."
 		return 2
 	fi
 	# Get characteristics of the extracted image
-	curImg=`ls -1 "$curOrigImg"*`
+	curImg=`ls -1 "$curOrigImg"* 2>/dev/null`
 	propCurImg=`identify -format "%w %h %[colorspace]" "$curImg"`
 	widthCurImg=`echo "$propCurImg" | cut -f1 -d" "`
 	heightCurImg=`echo "$propCurImg" | cut -f2 -d" "`