Use netpbm iso convert. Keeps grayscales grayscale.

diff --git a/scm/ps-to-png.scm b/scm/ps-to-png.scm
index 11515f1dea47b6f89d9ab3c4159ec05ce1ff9e44..19473b9a638fa08c559bbffb319a7693edaa7207 100644 (file)
--- a/scm/ps-to-png.scm
+++ b/scm/ps-to-png.scm
@@ -94,13 +94,16 @@
 
 (define (scale-down-image be-verbose factor file)
   (let* ((status 0)
-        (percentage (* 100 (/ 1.0 factor)))
+        ;;(percentage (* 100 (/ 1.0 factor)))
         (old (string-append file ".old")))
 
     (rename-file file old)
     (my-system
      be-verbose #t
-     (format #f "convert -scale \"~a%\" -depth 8 ~a ~a" percentage old file))
+     ;; convert -scale creates (a large rgb) png from a grayscale
+     ;; (format #f "convert -scale \"~a%\" -depth 8 ~a ~a" percentage old file))
+
+     (format #f "pngtopnm ~a | pnmscale -reduce ~a | pnmtopng > ~a" old factor file))
     (delete-file old)))
 
 (define-public (ps-page-count ps-name)
@@ -197,7 +200,6 @@
           ))
 
      (if (not (= 1 anti-alias-factor))
-        (for-each  (lambda (f) (scale-down-image be-verbose anti-alias-factor f))
-                   files))
-
+        (for-each
+         (lambda (f) (scale-down-image be-verbose anti-alias-factor f)) files))
      files)))