diff --git a/pipi/filter/color.c b/pipi/filter/color.c
index 529faf5..bbc191b 100644
--- a/pipi/filter/color.c
+++ b/pipi/filter/color.c
@@ -70,7 +70,7 @@ pipi_image_t *pipi_brightness(pipi_image_t *src, double val)
                     p = srcdata[d + 2];
                     dstdata[d + 2] = p < 1. - val ? p + val : 1.;
                     p = srcdata[d + 3];
-                    dstdata[d + 3] = p < 1. - val ? p + val : 1.;
+                    dstdata[d + 3] = p;
                 }
             }
         }
@@ -98,7 +98,7 @@ pipi_image_t *pipi_brightness(pipi_image_t *src, double val)
                     p = srcdata[d + 2];
                     dstdata[d + 2] = p > -val ? p + val : 0.;
                     p = srcdata[d + 3];
-                    dstdata[d + 3] = p > -val ? p + val : 0.;
+                    dstdata[d + 3] = p;
                 }
             }
         }
@@ -156,7 +156,7 @@ pipi_image_t *pipi_contrast(pipi_image_t *src, double val)
                     p = (srcdata[d + 2] - 0.5) * val + 0.5;
                     dstdata[d + 2] = p < 0. ? 0. : p > 1. ? 1. : p;
                     p = (srcdata[d + 3] - 0.5) * val + 0.5;
-                    dstdata[d + 3] = p < 0. ? 0. : p > 1. ? 1. : p;
+                    dstdata[d + 3] = p;
                 }
             }
         }
@@ -189,7 +189,7 @@ pipi_image_t *pipi_contrast(pipi_image_t *src, double val)
                     p = srcdata[d + 2];
                     dstdata[d + 2] = (p - 0.5) * val + 0.5;
                     p = srcdata[d + 3];
-                    dstdata[d + 3] = (p - 0.5) * val + 0.5;
+                    dstdata[d + 3] = p;
                 }
             }
         }