diff --git a/pipi/filter/convolution_template.h b/pipi/filter/convolution_template.h
index 595d1e7..1267ee3 100644
--- a/pipi/filter/convolution_template.h
+++ b/pipi/filter/convolution_template.h
@@ -70,7 +70,7 @@ static pipi_image_t *FUNC1(pipi_image_t *src, int m, int n, double mat[])
                     }
                 }
 
-                dstdata[y * w + x] = Y;
+                dstdata[y * w + x] = Y < 0.0 ? 0.0 : Y > 1.0 ? 1.0 : Y;
             }
             else
             {
@@ -97,9 +97,9 @@ static pipi_image_t *FUNC1(pipi_image_t *src, int m, int n, double mat[])
                     }
                 }
 
-                dstdata[off] = R;
-                dstdata[off + 1] = G;
-                dstdata[off + 2] = B;
+                dstdata[off] = R < 0.0 ? 0.0 : R > 1.0 ? 1.0 : R;
+                dstdata[off + 1] = G < 0.0 ? 0.0 : G > 1.0 ? 1.0 : G;
+                dstdata[off + 2] = B < 0.0 ? 0.0 : B > 1.0 ? 1.0 : B;
             }
         }
     }
@@ -193,7 +193,7 @@ static pipi_image_t *FUNC2(pipi_image_t *src,
                     Y += vvec[j] * buffer[y2 * w + x];
                 }
 
-                dstdata[y * w + x] = Y;
+                dstdata[y * w + x] = Y < 0.0 ? 0.0 : Y > 1.0 ? 1.0 : Y;
             }
             else
             {
@@ -213,9 +213,9 @@ static pipi_image_t *FUNC2(pipi_image_t *src,
                     B += f * buffer[(y2 * w + x) * 4 + 2];
                 }
 
-                dstdata[off] = R;
-                dstdata[off + 1] = G;
-                dstdata[off + 2] = B;
+                dstdata[off] = R < 0.0 ? 0.0 : R > 1.0 ? 1.0 : R;
+                dstdata[off + 1] = G < 0.0 ? 0.0 : G > 1.0 ? 1.0 : G;
+                dstdata[off + 2] = B < 0.0 ? 0.0 : B > 1.0 ? 1.0 : B;
             }
         }
     }