1 files changed, 47 insertions, 0 deletions
diff --git a/tex/context/base/grph-wnd.lua b/tex/context/base/grph-wnd.lua
new file mode 100644
index 000000000..0047651bf
--- /dev/null
+++ b/tex/context/base/grph-wnd.lua
@@ -0,0 +1,47 @@
+if not modules then modules = { } end modules ['grph-wnd'] = {
+    version   = 1.001,
+    comment   = "companion to grph-inc.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+-- Thanks to Luigi Scarso for making graphic magic work in luatex.
+--
+-- \externalfigure[hacker.jpeg][width=4cm,conversion=gray.jpg]
+
+local converters, suffixes = figures.converters, figures.suffixes
+
+local trace_conversion = false  trackers.register("figures.conversion", function(v) trace_conversion = v end)
+
+local report_graphics = logs.new("graphics")
+
+local function togray(oldname,newname)
+    if lfs.isfile(oldname) then
+        require("gmwand")
+        if trace_conversion then
+            report_graphics("converting '%s' to '%s' using gmwand",oldname,newname)
+        end
+        gmwand.InitializeMagick("./") -- What does this path do?
+        local wand = gmwand.NewMagickWand()
+        gmwand.MagickReadImage(wand,oldname)
+        gmwand.MagickSetImageColorspace(wand,gmwand.GRAYColorspace)
+        gmwand.MagickWriteImages(wand,newname,1)
+        gmwand.DestroyMagickWand(wand)
+    else
+        report_graphics("unable to convert '%s' to '%s' using gmwand",oldname,newname)
+    end
+end
+
+local formats = { "png", "jpg", "gif" }
+
+for i=1,#formats do
+    local oldformat = formats[i]
+    local newformat = "gray." .. oldformat
+    if trace_conversion then
+        report_graphics("installing converter: %s -> %s",oldformat,newformat)
+    end
+    converters[oldformat]            = converters[oldformat] or { }
+    converters[oldformat][newformat] = togray
+    suffixes  [newformat]            = oldformat
+end