diff --git a/MagickCore/thread-private.h b/MagickCore/thread-private.h
index 2b759f5..ab2578c 100644
--- a/MagickCore/thread-private.h
+++ b/MagickCore/thread-private.h
@@ -24,16 +24,16 @@
#include <MagickCore/thread_.h>
-#define IsConcurrentArea(columns,rows) \
- if (((((columns) > 64) || ((rows) > 64))) && \
- ((MagickSizeType) (columns*rows) > (64*64))) \
+#define IsConcurrentUno(colors,threshold) \
+ if ((colors) > threshold) \
num_threads(GetMagickResourceLimit(ThreadResource))
-#define IsConcurrentAreaExp(columns,rows,expression) \
- if (((((columns) > 64) || ((rows) > 64))) && \
- ((MagickSizeType) (columns*rows) > (64*64)) && (expression)) \
+#define IsConcurrentDos(columns,rows,threshold) \
+ if (((((columns) > threshold) || ((rows) > threshold))) && \
+ ((MagickSizeType) (columns*rows) > (threshold*threshold))) \
num_threads(GetMagickResourceLimit(ThreadResource))
-#define IsConcurrentColors(colors) \
- if ((colors) > 256) \
+#define IsConcurrentTres(columns,rows,expression,threshold) \
+ if (((((columns) > threshold) || ((rows) > threshold))) && \
+ ((MagickSizeType) (columns*rows) > (threshold*threshold)) && (expression)) \
num_threads(GetMagickResourceLimit(ThreadResource))
#if (__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR > 10))