diff --git a/README.md b/README.md
index 0c5f542..2158f5e 100644
--- a/README.md
+++ b/README.md
@@ -12,32 +12,34 @@ npm i git://github.com/ykob/glsl-util.git
 
 this function converts RGB to HSV. or is its opposite.
 
-### Quote source
-
 http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl
 
-### usage
-
 ```
 #pragma glslify: convertHsvToRgb = require(glsl-util/convertHsvToRgb);
 #pragma glslify: convertRgbToHsv = require(glsl-util/convertRgbToHsv);
+vec3 rgb = convertHsvToRgb(vec3 hsv);
+vec3 hsv = convertRgbToHsv(vec3 rgb);
 ```
 
 ## random
 
-### usage
-
 ```
 #pragma glslify: random = require(glsl-util/random);
+float p = random(vec2 c);
 ```
 
 ## polar
 
 this function calculates polar coordinates.
 
-### usage
-
 ```
 #pragma glslify: polar = require(glsl-util/polar);
 vec3 p = polar(float radian1, float radian2, float radius);
 ```
+
+## gaussianBlur
+
+```
+#pragma glslify: gaussianBlur = require(glsl-util/gaussianBlur);
+vec4 color = gaussianBlur(sampler2D texture, vec2 uv, float radius, vec2 resolution, vec2 direction);
+```
diff --git a/gaussianBlur.glsl b/gaussianBlur.glsl
new file mode 100644
index 0000000..f08146a
--- /dev/null
+++ b/gaussianBlur.glsl
@@ -0,0 +1,15 @@
+vec4 gaussianBlur(sampler2D texture, vec2 uv, float radius, vec2 resolution, vec2 direction) {
+  vec4 color = vec4(0.0);
+  vec2 step = radius / resolution * direction;
+  color += texture2D(texture, uv - 4.0 * step) * 0.02699548325659403;
+  color += texture2D(texture, uv - 3.0 * step) * 0.06475879783294587;
+  color += texture2D(texture, uv - 2.0 * step) * 0.12098536225957168;
+  color += texture2D(texture, uv - 1.0 * step) * 0.17603266338214976;
+  color += texture2D(texture, uv) * 0.19947114020071635;
+  color += texture2D(texture, uv + 1.0 * step) * 0.17603266338214976;
+  color += texture2D(texture, uv + 2.0 * step) * 0.12098536225957168;
+  color += texture2D(texture, uv + 3.0 * step) * 0.06475879783294587;
+  color += texture2D(texture, uv + 4.0 * step) * 0.02699548325659403;
+  return color;
+}
+#pragma glslify: export(gaussianBlur)