tools/boot/*/boot-x86: Prevent custom splash images from being modified

The related code seems to have been useful a long time ago (the need to use
  an RLE file and to reduce the number of colours to 16 has been dropped as of
  syslinux version 3.62). So replace obsolete code with a simple cp command.

Signed-off-by: Wolfgang Schweer <wschweer@arcor.de>

debian/changelog

@@ -2,6 +2,12 @@ debian-cd (3.1.34) UNRELEASED; urgency=medium
 
   * data/bullseye: Update Debian Edu installer logo and syslinux splash image
     from src:debian-edu-artwork 2.11.5-1.
+  * tools/boot/*/boot-x86: Prevent custom splash images from being modified.
+    The related code seems to have been useful a long time ago (the need to use
+    an RLE file and to reduce the number of colours to 16 has been dropped as of
+    syslinux version 3.62). So replace obsolete code with a simple cp command.
+  * debian/control: Drop Recommends: on netpbm and syslinux-utils. These are no
+    longer needed now that custom splash images are used unmodified.
 
  -- Wolfgang Schweer <wschweer@arcor.de>  Fri, 12 Feb 2021 22:07:27 +0100
 

debian/control

@@ -16,7 +16,7 @@ Vcs-Browser: https://salsa.debian.org/images-team/debian-cd
 Package: debian-cd
 Architecture: all
 Depends: ${misc:Depends}, curl, perl, dpkg-dev, cpp, libdigest-md5-perl, libdigest-sha-perl, tofrodos, apt, make, xorriso | genisoimage, lynx, grep-dctrl, bc, libcompress-zlib-perl, bzip2, libdpkg-perl, wget
-Recommends: hfsutils, netpbm, isolinux, syslinux-common, syslinux-utils, mtools, dosfstools
+Recommends: hfsutils, isolinux, syslinux-common, mtools, dosfstools
 Description: Tools for building (Official) Debian CD set
  Debian-cd is the official tool for building Debian CD set since the potato
  release. It was formerly called YACS (for Yet Another CD Script).

tools/boot/bullseye/boot-x86

@@ -380,11 +380,7 @@ EOF
 fi
 
 if [ "$SPLASHPNG" ] ; then
-    # Insert our own splash screen.  Color index 0 is background, and
+    cp $SPLASHPNG boot$N/isolinux/splash.png
-    # index 7 is foreground.  Set to black and white respecively
-    pngtopnm < $SPLASHPNG | ppmquant 16 | \
-        ppmtolss16 "#ffffff=7" "#000000=0" > boot$N/isolinux/splash.rle
-    pngtopnm < $SPLASHPNG | ppmquant 16 | pnmtopng  > boot$N/isolinux/splash.png
 fi
 
 # used by Debian Edu

tools/boot/buster/boot-x86

@@ -406,11 +406,7 @@ EOF
 fi
 
 if [ "$SPLASHPNG" ] ; then
-    # Insert our own splash screen.  Color index 0 is background, and
+    cp $SPLASHPNG boot$N/isolinux/splash.png
-    # index 7 is foreground.  Set to black and white respecively
-    pngtopnm < $SPLASHPNG | ppmquant 16 | \
-        ppmtolss16 "#ffffff=7" "#000000=0" > boot$N/isolinux/splash.rle
-    pngtopnm < $SPLASHPNG | ppmquant 16 | pnmtopng  > boot$N/isolinux/splash.png
 fi
 
 # used by Debian Edu

tools/boot/jessie/boot-x86

@@ -387,11 +387,7 @@ else
 fi
 
 if [ "$SPLASHPNG" ] ; then
-    # Insert our own splash screen.  Color index 0 is background, and
+    cp $SPLASHPNG boot$N/isolinux/splash.png
-    # index 7 is foreground.  Set to black and white respecively
-    pngtopnm < $SPLASHPNG | ppmquant 16 | \
-        ppmtolss16 "#ffffff=7" "#000000=0" > boot$N/isolinux/splash.rle
-    pngtopnm < $SPLASHPNG | ppmquant 16 | pnmtopng  > boot$N/isolinux/splash.png
 fi
 
 # used by Debian Edu

tools/boot/stretch/boot-x86

@@ -404,11 +404,7 @@ EOF
 fi
 
 if [ "$SPLASHPNG" ] ; then
-    # Insert our own splash screen.  Color index 0 is background, and
+    cp $SPLASHPNG boot$N/isolinux/splash.png
-    # index 7 is foreground.  Set to black and white respecively
-    pngtopnm < $SPLASHPNG | ppmquant 16 | \
-        ppmtolss16 "#ffffff=7" "#000000=0" > boot$N/isolinux/splash.rle
-    pngtopnm < $SPLASHPNG | ppmquant 16 | pnmtopng  > boot$N/isolinux/splash.png
 fi
 
 # used by Debian Edu