diff --git a/pipi/context.c b/pipi/context.c
index 068fc51..9b3996c 100644
--- a/pipi/context.c
+++ b/pipi/context.c
@@ -91,6 +91,7 @@ pipi_command_t const *pipi_get_command_list(void)
         { "overlay", 0 },
         { "line", 1 },
         { "sine", 1 },
+        { "wave", 1 },
 
         /* End marker */
         { NULL, 0 }
@@ -647,9 +648,9 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
                        x1,  y1,  x2,  y2, color, aa);
         ctx->nimages++;
     }
-    else if(!strcmp(cmd, "sine"))
+    else if(!strcmp(cmd, "sine") || !strcmp(cmd, "wave"))
     {
-        pipi_image_t *tmp;
+        pipi_image_t *src, *dst = NULL;
         char const *arg;
         va_list ap;
         float dw, dh, d = 0.0, a = 0.0;
@@ -666,9 +667,16 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
         if(ret < 2)
             return -1;
 
-        tmp = ctx->images[ctx->nimages - 1];
-        ctx->images[ctx->nimages - 1] = pipi_sine(tmp, dw, dh, d, a);
-        pipi_free(tmp);
+        src = ctx->images[ctx->nimages - 1];
+        switch(cmd[0])
+        {
+            case 's': dst = pipi_sine(src, dw, dh, d, a); break;
+            case 'w': dst = pipi_wave(src, dw, dh, d, a); break;
+        }
+        if(dst == NULL)
+            return -1;
+        pipi_free(src);
+        ctx->images[ctx->nimages - 1] = dst;
     }
     else
     {
diff --git a/pipi/filter/wave.c b/pipi/filter/wave.c
index 9851f4c..5e0e400 100644
--- a/pipi/filter/wave.c
+++ b/pipi/filter/wave.c
@@ -28,6 +28,78 @@
 
 #define BORDER 64
 
+pipi_image_t *pipi_wave(pipi_image_t *src, double dw, double dh,
+                        double d, double a)
+{
+    pipi_image_t *dst;
+    pipi_pixels_t *srcp, *dstp;
+    float *srcdata, *dstdata;
+    double sina, cosa;
+    int x, y, w, h, i, gray;
+
+    w = src->w;
+    h = src->h;
+
+    gray = (src->last_modified == PIPI_PIXELS_Y_F32);
+
+    srcp = gray ? pipi_get_pixels(src, PIPI_PIXELS_Y_F32)
+                : pipi_get_pixels(src, PIPI_PIXELS_RGBA_F32);
+    srcdata = (float *)srcp->pixels;
+
+    dst = pipi_new(w, h);
+    dstp = gray ? pipi_get_pixels(dst, PIPI_PIXELS_Y_F32)
+                : pipi_get_pixels(dst, PIPI_PIXELS_RGBA_F32);
+    dstdata = (float *)dstp->pixels;
+
+    sina = sin(a);
+    cosa = cos(a);
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            double angle = 2 * M_PI / dw * ((x - w / 2) * cosa
+                                             + (y - h / 2) * sina - d);
+            double displacement = dh * sin(angle);
+            double dx, dy;
+            int x2, y2;
+
+            dx = cosa * displacement;
+            dy = sina * displacement;
+
+            if(x < BORDER) dx = dx * x / BORDER;
+            if(x > w - 1 - BORDER) dx = dx * (w - 1 - x) / BORDER;
+            if(y < BORDER) dy = dy * y / BORDER;
+            if(y > h - 1 - BORDER) dy = dy * (h - 1 - y) / BORDER;
+
+            x2 = x + dx;
+            y2 = y + dy;
+
+            /* Just in case... */
+            if(x2 < 0) x2 = 0;
+            else if(x2 >= w) x2 = w - 1;
+
+            if(y2 < 0) y2 = 0;
+            else if(y2 >= h) y2 = h - 1;
+
+            if(gray)
+            {
+                dstdata[y * w + x] = srcdata[y2 * w + x2];
+            }
+            else
+            {
+                for(i = 0; i < 4; i++)
+                {
+                    dstdata[4 * (y * w + x) + i]
+                        = srcdata[4 * (y2 * w + x2) + i];
+                }
+            }
+        }
+    }
+
+    return dst;
+}
+
 pipi_image_t *pipi_sine(pipi_image_t *src, double dw, double dh,
                         double d, double a)
 {
diff --git a/pipi/pipi.h b/pipi/pipi.h
index f2e9f8b..16ce6f9 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -201,6 +201,8 @@ __extern pipi_image_t *pipi_dilate(pipi_image_t *);
 __extern pipi_image_t *pipi_erode(pipi_image_t *);
 __extern pipi_image_t *pipi_sine(pipi_image_t *, double, double,
                                  double, double);
+__extern pipi_image_t *pipi_wave(pipi_image_t *, double, double,
+                                 double, double);
 
 __extern pipi_image_t *pipi_order(pipi_image_t *);