From 1d820885276fedcfe30aa1dae4419aba2d14623c Mon Sep 17 00:00:00 2001
From: Dirk Surmann <4048472+surmann@users.noreply.github.com>
Date: Thu, 9 Dec 2021 16:49:40 +0100
Subject: [PATCH 1/4] add brightness switch

---
 scan         | 6 ++++++
 scan_perpage | 9 +++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/scan b/scan
index 3d6fd2c..33355c7 100755
--- a/scan
+++ b/scan
@@ -31,6 +31,7 @@ DESKEW=0
 DRIVER_OPTION=
 VERBOSE=0
 SKIP_EMPTY_PAGES=0
+BRIGHTNESS=0
 SOURCE=""
 
 TMP_DIR=$(mktemp -d -p "" scan.XXXXXXXXXX)
@@ -94,6 +95,8 @@ while [[ $# > 0 ]]; do
 
   -xo|--driver-options) shift; DRIVER_OPTION=$1;;
 
+  --brightness) BRIGHTNESS=1 ;;
+
   *) if [[ $USEARRAY == 1 ]]; then OUTPUTARR+=("$1"); else echo >&2 "Unknown argument: $1"; exit 1; fi ;;
 
   esac
@@ -145,6 +148,8 @@ if [[ $HELP == 1 ]]; then
   echo "   which language to use for OCR"
   echo " --skip-empty-pages"
   echo "   remove empty pages from resulting PDF document (e.g. one sided doc in duplex mode)"
+  echo " --brightness"
+  echo "   Increase brightness and contrast in post-processing"
   echo ""
   echo "OUTPUT"
   echo " -o, --output <outputfile>"
@@ -267,6 +272,7 @@ export PGWIDTHIN
 export PGHEIGHTIN
 export PS2PDF_OPTS
 export SKIP_EMPTY_PAGES
+export BRIGHTNESS
 
 if [[ $VERBOSE == 1 ]]; then
   LOCKFILE=$(mktemp)
diff --git a/scan_perpage b/scan_perpage
index eb0dc80..fe27733 100755
--- a/scan_perpage
+++ b/scan_perpage
@@ -14,6 +14,7 @@ usage()
   echo "  PGWIDTHIN"
   echo "  PGHEIGHTIN"
   echo "  SKIP_EMPTY_PAGES"
+  echo "  BRIGHTNESS"
   echo "  PS2PDF_OPTS (optional)"
   echo "  VERBOSE (optional)"
   echo "  LOCKFILE (required if VERBOSE=1)"
@@ -50,7 +51,7 @@ if [[ $# < 1 ]]; then
   exit 1
 fi
 
-if [[ "$UNPAPER" == "" || "$SEARCHABLE" == "" || "$RESOLUTION" == "" || "$RESOLUTION" == "" || "$SKIP_EMPTY_PAGES" == "" ]]; then
+if [[ "$UNPAPER" == "" || "$SEARCHABLE" == "" || "$RESOLUTION" == "" || "$RESOLUTION" == "" || "$SKIP_EMPTY_PAGES" == "" || "$BRIGHTNESS" == "" ]]; then
   usage
   exit 1
 fi
@@ -67,9 +68,13 @@ fi
 process_page() {
   log ""
   log "-------------------------------------------------------------------------------"
-  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES..."
+  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES, brightness=$BRIGHTNESS..."
   log "-------------------------------------------------------------------------------"
 
+  if [[ $BRIGHTNESS == 1 ]]; then
+    convert "$IMAGE_PATH" -brightness-contrast 20x10 "$IMAGE_PATH"
+  fi
+
   if [[ $SKIP_EMPTY_PAGES == 1 ]]; then
     PERCENTAGE_WHITE=$(convert "$IMAGE_PATH" -fuzz 0% -negate -threshold 0 -negate -format "%[fx:100*mean]" info:) || PERCENTAGE_WHITE=0
     log "$IMAGE_PATH has $PERCENTAGE_WHITE % white"

From bed68a0e7b212a5cadb54b7a051f663b53a2408d Mon Sep 17 00:00:00 2001
From: Dirk Surmann <4048472+surmann@users.noreply.github.com>
Date: Thu, 9 Dec 2021 16:48:55 +0100
Subject: [PATCH 2/4] add white threshold to skip pages

---
 scan         | 10 ++++++++--
 scan_perpage |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/scan b/scan
index 33355c7..cc619b3 100755
--- a/scan
+++ b/scan
@@ -31,6 +31,7 @@ DESKEW=0
 DRIVER_OPTION=
 VERBOSE=0
 SKIP_EMPTY_PAGES=0
+WHITE_THRESHOLD=
 BRIGHTNESS=0
 SOURCE=""
 
@@ -85,7 +86,7 @@ while [[ $# > 0 ]]; do
 
   --language) shift; LANGUAGE=$1 ;;
 
-  --skip-empty-pages) SKIP_EMPTY_PAGES=1 ;;
+  --skip-empty-pages) SKIP_EMPTY_PAGES=1; WHITE_THRESHOLD=$1 ;;
 
   -o|--output) shift; USEOUTPUT=1; OUTPUT="$1" ;;
 
@@ -146,8 +147,9 @@ if [[ $HELP == 1 ]]; then
   echo "   Run OCR to make the PDF searchable (requires tesseract)"
   echo " --language <lang>"
   echo "   which language to use for OCR"
-  echo " --skip-empty-pages"
+  echo " --skip-empty-pages <threshold>"
   echo "   remove empty pages from resulting PDF document (e.g. one sided doc in duplex mode)"
+  echo "   the threshold to identify an empty page is a percentage value between 0 and 100. The default is 99.8"
   echo " --brightness"
   echo "   Increase brightness and contrast in post-processing"
   echo ""
@@ -262,6 +264,9 @@ if [[ $SKIP_EMPTY_PAGES == 1 && ! -x "$(command -v bc)" ]]; then
   echo >&2 'Warning: `--skip-empty-pages` specified, but `bc` not available. Disabling empty page detection.'
   SKIP_EMPTY_PAGES=0
 fi
+if [[ $SKIP_EMPTY_PAGES == 1 && $WHITE_THRESHOLD == "" ]]; then
+  WHITE_THRESHOLD=99.8
+fi
 
 export VERBOSE
 export UNPAPER
@@ -272,6 +277,7 @@ export PGWIDTHIN
 export PGHEIGHTIN
 export PS2PDF_OPTS
 export SKIP_EMPTY_PAGES
+export WHITE_THRESHOLD
 export BRIGHTNESS
 
 if [[ $VERBOSE == 1 ]]; then
diff --git a/scan_perpage b/scan_perpage
index fe27733..3eada08 100755
--- a/scan_perpage
+++ b/scan_perpage
@@ -83,7 +83,7 @@ process_page() {
   fi
 
   PP_PREFIX=
-  if [[ $SKIP_EMPTY_PAGES == 1 && $(echo "$PERCENTAGE_WHITE > 99.8" | bc -l) == 1 ]]; then
+  if [[ $SKIP_EMPTY_PAGES == 1 && $(echo "$PERCENTAGE_WHITE > $WHITE_THRESHOLD" | bc -l) == 1 ]]; then
     log "Skipping empty page $IMAGE_FILE with white percentage $PERCENTAGE_WHITE"
   else
     if [[ $UNPAPER == 1 ]]; then

From 476e730135cd91b7bd10eac1acd9a122abbbd90d Mon Sep 17 00:00:00 2001
From: Dirk Surmann <4048472+surmann@users.noreply.github.com>
Date: Thu, 9 Dec 2021 18:03:06 +0100
Subject: [PATCH 3/4] update white threshold

---
 scan         | 14 +++++++-------
 scan_perpage |  2 +-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/scan b/scan
index cc619b3..6a4e644 100755
--- a/scan
+++ b/scan
@@ -31,7 +31,7 @@ DESKEW=0
 DRIVER_OPTION=
 VERBOSE=0
 SKIP_EMPTY_PAGES=0
-WHITE_THRESHOLD=
+WHITE_THRESHOLD=99.8
 BRIGHTNESS=0
 SOURCE=""
 
@@ -86,7 +86,9 @@ while [[ $# > 0 ]]; do
 
   --language) shift; LANGUAGE=$1 ;;
 
-  --skip-empty-pages) SKIP_EMPTY_PAGES=1; WHITE_THRESHOLD=$1 ;;
+  --skip-empty-pages) SKIP_EMPTY_PAGES=1 ;;
+
+  --white-threshold) shift; WHITE_THRESHOLD=$1 ;;
 
   -o|--output) shift; USEOUTPUT=1; OUTPUT="$1" ;;
 
@@ -147,9 +149,10 @@ if [[ $HELP == 1 ]]; then
   echo "   Run OCR to make the PDF searchable (requires tesseract)"
   echo " --language <lang>"
   echo "   which language to use for OCR"
-  echo " --skip-empty-pages <threshold>"
+  echo " --skip-empty-pages"
   echo "   remove empty pages from resulting PDF document (e.g. one sided doc in duplex mode)"
-  echo "   the threshold to identify an empty page is a percentage value between 0 and 100. The default is 99.8"
+  echo " --white-threshold"
+  echo "   threshold to identify an empty page is a percentage value between 0 and 100. The default is 99.8"
   echo " --brightness"
   echo "   Increase brightness and contrast in post-processing"
   echo ""
@@ -264,9 +267,6 @@ if [[ $SKIP_EMPTY_PAGES == 1 && ! -x "$(command -v bc)" ]]; then
   echo >&2 'Warning: `--skip-empty-pages` specified, but `bc` not available. Disabling empty page detection.'
   SKIP_EMPTY_PAGES=0
 fi
-if [[ $SKIP_EMPTY_PAGES == 1 && $WHITE_THRESHOLD == "" ]]; then
-  WHITE_THRESHOLD=99.8
-fi
 
 export VERBOSE
 export UNPAPER
diff --git a/scan_perpage b/scan_perpage
index 3eada08..5fa4a72 100755
--- a/scan_perpage
+++ b/scan_perpage
@@ -68,7 +68,7 @@ fi
 process_page() {
   log ""
   log "-------------------------------------------------------------------------------"
-  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES, brightness=$BRIGHTNESS..."
+  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES, white-threshold=$WHITE_THRESHOLD, brightness=$BRIGHTNESS..."
   log "-------------------------------------------------------------------------------"
 
   if [[ $BRIGHTNESS == 1 ]]; then

From 13c40dcfce42f71dbfc32c3078af2d24463215f6 Mon Sep 17 00:00:00 2001
From: Dirk Surmann <4048472+surmann@users.noreply.github.com>
Date: Sat, 1 Jan 2022 13:23:44 +0100
Subject: [PATCH 4/4] update brightness and contrast control

---
 scan         | 11 ++++++-----
 scan_perpage | 11 ++++++-----
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/scan b/scan
index 6a4e644..b539283 100755
--- a/scan
+++ b/scan
@@ -32,7 +32,7 @@ DRIVER_OPTION=
 VERBOSE=0
 SKIP_EMPTY_PAGES=0
 WHITE_THRESHOLD=99.8
-BRIGHTNESS=0
+BRIGHTNESS_CONTRAST=
 SOURCE=""
 
 TMP_DIR=$(mktemp -d -p "" scan.XXXXXXXXXX)
@@ -98,7 +98,7 @@ while [[ $# > 0 ]]; do
 
   -xo|--driver-options) shift; DRIVER_OPTION=$1;;
 
-  --brightness) BRIGHTNESS=1 ;;
+  --brightness-contrast-sw) shift; BRIGHTNESS_CONTRAST=$1 ;;
 
   *) if [[ $USEARRAY == 1 ]]; then OUTPUTARR+=("$1"); else echo >&2 "Unknown argument: $1"; exit 1; fi ;;
 
@@ -153,8 +153,9 @@ if [[ $HELP == 1 ]]; then
   echo "   remove empty pages from resulting PDF document (e.g. one sided doc in duplex mode)"
   echo " --white-threshold"
   echo "   threshold to identify an empty page is a percentage value between 0 and 100. The default is 99.8"
-  echo " --brightness"
-  echo "   Increase brightness and contrast in post-processing"
+  echo " --brightness-contrast-sw"
+  echo "   Alter brightness and contrast via post-processing - prefer specifying brightness and/or"
+  echo "   contrast via --driver-options if supported by your hardware."
   echo ""
   echo "OUTPUT"
   echo " -o, --output <outputfile>"
@@ -278,7 +279,7 @@ export PGHEIGHTIN
 export PS2PDF_OPTS
 export SKIP_EMPTY_PAGES
 export WHITE_THRESHOLD
-export BRIGHTNESS
+export BRIGHTNESS_CONTRAST
 
 if [[ $VERBOSE == 1 ]]; then
   LOCKFILE=$(mktemp)
diff --git a/scan_perpage b/scan_perpage
index 5fa4a72..d3a2a74 100755
--- a/scan_perpage
+++ b/scan_perpage
@@ -14,7 +14,7 @@ usage()
   echo "  PGWIDTHIN"
   echo "  PGHEIGHTIN"
   echo "  SKIP_EMPTY_PAGES"
-  echo "  BRIGHTNESS"
+  echo "  BRIGHTNESS_CONTRAST"
   echo "  PS2PDF_OPTS (optional)"
   echo "  VERBOSE (optional)"
   echo "  LOCKFILE (required if VERBOSE=1)"
@@ -51,7 +51,7 @@ if [[ $# < 1 ]]; then
   exit 1
 fi
 
-if [[ "$UNPAPER" == "" || "$SEARCHABLE" == "" || "$RESOLUTION" == "" || "$RESOLUTION" == "" || "$SKIP_EMPTY_PAGES" == "" || "$BRIGHTNESS" == "" ]]; then
+if [[ "$UNPAPER" == "" || "$SEARCHABLE" == "" || "$RESOLUTION" == "" || "$RESOLUTION" == "" || "$SKIP_EMPTY_PAGES" == "" ]]; then
   usage
   exit 1
 fi
@@ -68,11 +68,12 @@ fi
 process_page() {
   log ""
   log "-------------------------------------------------------------------------------"
-  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES, white-threshold=$WHITE_THRESHOLD, brightness=$BRIGHTNESS..."
+  log "Post-processing scanned page ${IMAGE_PATH}, deskew=$UNPAPER, searchable=$SEARCHABLE, skip-empty-pages=$SKIP_EMPTY_PAGES, white-threshold=$WHITE_THRESHOLD, brightness-contrast-sw=$BRIGHTNESS_CONTRAST..."
   log "-------------------------------------------------------------------------------"
 
-  if [[ $BRIGHTNESS == 1 ]]; then
-    convert "$IMAGE_PATH" -brightness-contrast 20x10 "$IMAGE_PATH"
+  if [[ "$BRIGHTNESS_CONTRAST" != "" ]]; then
+	log "Adjust brightness and contrast in ImageMagick by $BRIGHTNESS_CONTRAST"
+    convert "$IMAGE_PATH" -brightness-contrast $BRIGHTNESS_CONTRAST "$IMAGE_PATH"
   fi
 
   if [[ $SKIP_EMPTY_PAGES == 1 ]]; then