From 04b3ddfbf55d6ea7982c313f34e9ca8923d6d096 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@ucc.asn.au>
Date: Tue, 29 Mar 2011 21:55:09 +0800
Subject: [PATCH] Autodetect depth sensibly

---
 scan2pages.sh | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/scan2pages.sh b/scan2pages.sh
index 995c5a6..c9a10c8 100755
--- a/scan2pages.sh
+++ b/scan2pages.sh
@@ -7,7 +7,8 @@ Convert pdffile - a pdf of scanned facing pages - to a set of images in outdir,
 each with only one page.
 OPTIONS:
 	-v: Be verbose.
-	-d depth: Use given depth. Default is 1. Unpaper can only handle up to 8.
+	-d depth: Use given depth. Default is 1 for black and white, 8 for colour.
+		Unpaper can only handle up to 8.
 	-D dpi: Use given DPI. Colour scans on library scanners are usually 300, bw 400. 
 	-s: skip masking/trimming. Overrides -m.
 	-f: Forceably redo everything.
@@ -34,7 +35,8 @@ forceunpaper=
 forceclean=
 convertflags=
 unpaperflags=
-depthflags="-depth 1"
+depthset=
+depth=
 dpi=
 skipmask=
 verbose=
@@ -45,7 +47,7 @@ do
 		convertflags="$convertflags -verbose"
 		unpaperflags="$unpaperflags -v --time"
 		;;
-	d)	depthflags="-depth $OPTARG"
+	d)	depth="$OPTARG"
 		;;
 	D)	dpi=$OPTARG
 		;;
@@ -111,6 +113,18 @@ if [[ "$dpi" = "" ]]; then
 	fi
 fi
 
+# guess at depth, unless it's been set
+if [[ "$depth" = "" ]]; then
+	if [[ $( convert $file[0] -format "%k" info: || exit 1 ) == 2 ]]; then
+		depth=1;
+	else
+		depth=8
+	fi
+	if [[ $verbose == 1 ]]; then
+		echo "Depth guessed at $depth."
+	fi
+fi
+
 # process pages 1 by 1 to avoid convert gobbling all the memory
 for pg in `$my_seq 1 $pages`; do
 	echo "Processing page $pg."
@@ -120,7 +134,7 @@ for pg in `$my_seq 1 $pages`; do
 	# convert from pdf
 	origpnm=$dir/pg-${pgn}.pnm
 	if [[ ! $([ -e $origpnm ]) || $forcepdf ]]; then
-		convert $convertflags $depthflags -density $dpi $file[$(expr $pg - 1)] \
+		convert $convertflags -depth $depth -density $dpi $file[$(expr $pg - 1)] \
 			$origpnm || exit 1
 	fi;
 	
-- 
2.20.1