diff --git a/modules/joex/src/main/resources/reference.conf b/modules/joex/src/main/resources/reference.conf
index 35e48dc5..12f55c9f 100644
--- a/modules/joex/src/main/resources/reference.conf
+++ b/modules/joex/src/main/resources/reference.conf
@@ -147,16 +147,31 @@ docspell.joex {
   # below. They must be in the PATH environment or specify the full
   # path below via the `program` key.
   convert {
+
+    # The chunk size used when storing files. This should be the same
+    # as used with the rest server.
     chunk-size = 524288
 
-    max-image-size = 12000000
+    # When reading images, this is the maximum size. Images that are
+    # larger are not processed.
+    max-image-size = ${docspell.joex.extraction.ocr.max-image-size}
 
+    # Settings when processing markdown files (and other text files)
+    # to HTML.
+    #
+    # In order to support text formats, text files are first converted
+    # to HTML using a markdown processor. The resulting HTML is then
+    # converted to a PDF file.
     markdown {
+
+      # The CSS that is used to style the resulting HTML.
       internal-css = """
         body { padding: 2em 5em; }
       """
     }
 
+    # To convert HTML files into PDF files, the external tool
+    # wkhtmltopdf is used.
     wkhtmlpdf {
       cmd = {
         program = "wkhtmltopdf"
@@ -168,11 +183,13 @@ docspell.joex {
           "-",
           "{{outfile}}"
         ]
-        timeout = "20 seconds"
+        timeout = "2 minutes"
       }
       working-dir = ${java.io.tmpdir}"/docspell-convert"
     }
 
+    # To convert image files to PDF files, tesseract is used. This
+    # also extracts the text in one go.
     tesseract = {
       cmd = {
         program = "tesseract"
@@ -184,11 +201,19 @@ docspell.joex {
           "pdf",
           "txt"
         ]
-        timeout = "120 seconds"
+        timeout = "5 minutes"
       }
       working-dir = ${java.io.tmpdir}"/docspell-convert"
     }
 
+    # To convert "office" files to PDF files, the external tool
+    # unoconv is used. Unoconv uses libreoffice/openoffice for
+    # converting. So it supports all formats that are possible to read
+    # with libreoffice/openoffic.
+    #
+    # Note: to greatly improve performance, it is recommended to start
+    # a libreoffice listener by running `unoconv -l` in a separate
+    # process.
     unoconv = {
       cmd = {
         program = "unoconv"
@@ -199,7 +224,7 @@ docspell.joex {
           "{{outfile}}",
           "{{infile}}"
         ]
-        timeout = "20 seconds"
+        timeout = "2 minutes"
       }
       working-dir = ${java.io.tmpdir}"/docspell-convert"
     }