Docker: fix blank JPEG2000 PDF issue

Dockerfile

@@ -23,12 +23,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 RUN apt-get install -y --no-install-recommends \
   unpaper \
-  libopenjpeg-dev \
-  ghostscript \
   qpdf \
-  poppler-utils
-
-RUN apt-get install -y --no-install-recommends \
+  poppler-utils \
   tesseract-ocr \
   tesseract-ocr-deu tesseract-ocr-spa tesseract-ocr-eng tesseract-ocr-fra
 
@@ -37,6 +33,14 @@ RUN apt-get install -qy --no-install-recommends \
   libpython3-dev \
   gcc
 
+# Install Ghostscript from Debian sid to work around JPEG 2000 issue in
+# Debian stretch libgs9 or gs 9.16~dfsg-2.1
+
+COPY ./share/etc-apt-sources.list /etc/apt/sources.list
+
+RUN apt-get update && apt-get install -y ghostscript/sid
+
+
 # Enforce UTF-8
 # Borrowed from https://index.docker.io/u/crosbymichael/python/ 
 RUN dpkg-reconfigure locales && \

share/etc-apt-sources.list

@@ -0,0 +1,4 @@
+deb http://httpredir.debian.org/debian stretch main
+deb http://httpredir.debian.org/debian stretch-updates main
+deb http://security.debian.org stretch/updates main
+deb http://ftp.de.debian.org/debian sid main contrib non-free