From: Daniel Axtens <dja@ucc.asn.au>
Date: Mon, 28 Mar 2011 15:53:27 +0000 (+0800)
Subject: DPI support and detection
X-Git-Url: https://git.ucc.asn.au/?p=dja%2Fscandal.git;a=commitdiff_plain;h=3d2d99e7b6ce1522ad2c30ccfe24d3271c68cb47

DPI support and detection
---

diff --git a/scan2pages.sh b/scan2pages.sh
index 45f6215..995c5a6 100755
--- a/scan2pages.sh
+++ b/scan2pages.sh
@@ -8,6 +8,7 @@ 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 dpi: Use given DPI. Colour scans on library scanners are usually 300, bw 400. 
 	-s: skip masking/trimming. Overrides -m.
 	-f: Forceably redo everything.
 	-p: Forceably redo pdf conversion. Implies options below, equivalent to -f.
@@ -34,15 +35,20 @@ forceclean=
 convertflags=
 unpaperflags=
 depthflags="-depth 1"
+dpi=
 skipmask=
+verbose=
 while getopts 'vd:sfpmuc' OPTION
 do
 	case $OPTION in
-	v)  convertflags="$convertflags -verbose"
+	v)	verbose=1
+		convertflags="$convertflags -verbose"
 		unpaperflags="$unpaperflags -v --time"
 		;;
 	d)	depthflags="-depth $OPTARG"
 		;;
+	D)	dpi=$OPTARG
+		;;
 	s)	skipmask=1;
 		;;
 	f)	forcepdf=1; forcemask=1; forceunpaper=1; forceclean=1
@@ -88,6 +94,23 @@ pages=$(awk '$1 ~ "%%Pages" {print $2}' $dscname)
 echo "Got $pages page(s)."
 rm $dscname
 
+# guess at DPI, unless it's been set
+# the scans do not seem to accurately reflect their resolution.
+if [[ "$dpi" = "" ]]; then
+	# %k gives the number of colours/shades in the image.
+	# 2 for b/w, and the scanner seems to default to 400 dpi for that
+	# 256 for greyscale, which has to be selected manually (so I'm assuming 300 for no good reason)
+	# 31564 for colour, which defaults to 300
+	if [[ $( convert $file[0] -format "%k" info: || exit 1 ) == 2 ]]; then
+		dpi=400;
+	else
+		dpi=300
+	fi
+	if [[ $verbose == 1 ]]; then
+		echo "DPI guessed at $dpi."
+	fi
+fi
+
 # process pages 1 by 1 to avoid convert gobbling all the memory
 for pg in `$my_seq 1 $pages`; do
 	echo "Processing page $pg."
@@ -97,7 +120,7 @@ for pg in `$my_seq 1 $pages`; do
 	# convert from pdf
 	origpnm=$dir/pg-${pgn}.pnm
 	if [[ ! $([ -e $origpnm ]) || $forcepdf ]]; then
-		convert $convertflags $depthflags -density 300 $file[$(expr $pg - 1)] \
+		convert $convertflags $depthflags -density $dpi $file[$(expr $pg - 1)] \
 			$origpnm || exit 1
 	fi;