diff --git a/pipi/Makefile.am b/pipi/Makefile.am
index 444f1a1..0d06c2c 100644
--- a/pipi/Makefile.am
+++ b/pipi/Makefile.am
@@ -60,7 +60,7 @@ render_sources = \
 
 combine_sources = \
 	combine/rgb.c \
-	combine/mean.c \
+	combine/merge.c \
 	combine/minmax.c \
 	combine/subadd.c \
 	combine/mulscreen.c
diff --git a/pipi/combine/mean.c b/pipi/combine/merge.c
similarity index 79%
rename from pipi/combine/mean.c
rename to pipi/combine/merge.c
index e7efc51..dd6f7b9 100644
--- a/pipi/combine/mean.c
+++ b/pipi/combine/merge.c
@@ -23,16 +23,23 @@
 #include "pipi.h"
 #include "pipi_internals.h"
 
-pipi_image_t *pipi_mean(pipi_image_t *img1, pipi_image_t *img2)
+pipi_image_t *pipi_merge(pipi_image_t *img1, pipi_image_t *img2, double t)
 {
     pipi_image_t *dst;
     pipi_pixels_t *img1p, *img2p, *dstp;
     float *img1data, *img2data, *dstdata;
+    double t2;
     int x, y, w, h;
 
     if(img1->w != img2->w || img1->h != img2->h)
         return NULL;
 
+    if(t < 0.0)
+        t = 0.0;
+    else if(t > 1.0)
+        t = 1.0;
+    t2 = 1.0 - t;
+
     w = img1->w;
     h = img1->h;
 
@@ -53,22 +60,27 @@ pipi_image_t *pipi_mean(pipi_image_t *img1, pipi_image_t *img2)
 
             p = img1data[4 * (y * w + x)];
             q = img2data[4 * (y * w + x)];
-            dstdata[4 * (y * w + x)] = (p + q) * 0.5;
+            dstdata[4 * (y * w + x)] = t * p + t2 * q;
 
             p = img1data[4 * (y * w + x) + 1];
             q = img2data[4 * (y * w + x) + 1];
-            dstdata[4 * (y * w + x) + 1] = (p + q) * 0.5;
+            dstdata[4 * (y * w + x) + 1] = t * p + t2 * q;
 
             p = img1data[4 * (y * w + x) + 2];
             q = img2data[4 * (y * w + x) + 2];
-            dstdata[4 * (y * w + x) + 2] = (p + q) * 0.5;
+            dstdata[4 * (y * w + x) + 2] = t * p + t2 * q;
 
             p = img1data[4 * (y * w + x) + 3];
             q = img2data[4 * (y * w + x) + 3];
-            dstdata[4 * (y * w + x) + 3] = (p + q) * 0.5;
+            dstdata[4 * (y * w + x) + 3] = t * p + t2 * q;
         }
     }
 
     return dst;
 }
 
+pipi_image_t *pipi_mean(pipi_image_t *img1, pipi_image_t *img2)
+{
+    return pipi_merge(img1, img2, 0.5);
+}
+
diff --git a/pipi/context.c b/pipi/context.c
index 4238747..53f87c6 100644
--- a/pipi/context.c
+++ b/pipi/context.c
@@ -78,6 +78,7 @@ pipi_command_t const *pipi_get_command_list(void)
         { "combine", 0 },
         { "split", 0 },
         { "mean", 0 },
+        { "merge", 1 },
         { "min", 0 },
         { "max", 0 },
         { "add", 0 },
@@ -523,6 +524,30 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
         ctx->images[ctx->nimages - 2] = dst;
         ctx->nimages--;
     }
+    else if(!strcmp(cmd, "merge"))
+    {
+        pipi_image_t *dst;
+        char const *arg;
+        va_list ap;
+        double val;
+
+        if(ctx->nimages < 2)
+            return -1;
+
+        va_start(ap, cmd);
+        arg = va_arg(ap, char const *);
+        va_end(ap);
+        val = atof(arg);
+
+        dst = pipi_merge(ctx->images[ctx->nimages - 2],
+                         ctx->images[ctx->nimages - 1], val);
+        if(dst == NULL)
+            return -1;
+        pipi_free(ctx->images[ctx->nimages - 2]);
+        pipi_free(ctx->images[ctx->nimages - 1]);
+        ctx->images[ctx->nimages - 2] = dst;
+        ctx->nimages--;
+    }
     else if(!strcmp(cmd, "min"))
     {
         pipi_image_t *dst;
diff --git a/pipi/pipi.h b/pipi/pipi.h
index 9f7288b..7bda7c3 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -166,6 +166,7 @@ __extern pipi_image_t *pipi_rgb(pipi_image_t *, pipi_image_t *, pipi_image_t *);
 __extern pipi_image_t *pipi_red(pipi_image_t *);
 __extern pipi_image_t *pipi_green(pipi_image_t *);
 __extern pipi_image_t *pipi_blue(pipi_image_t *);
+__extern pipi_image_t *pipi_merge(pipi_image_t *, pipi_image_t *, double);
 __extern pipi_image_t *pipi_mean(pipi_image_t *, pipi_image_t *);
 __extern pipi_image_t *pipi_min(pipi_image_t *, pipi_image_t *);
 __extern pipi_image_t *pipi_max(pipi_image_t *, pipi_image_t *);