diff --git a/README.md b/README.md
index 551a5b7..c1acc58 100644
--- a/README.md
+++ b/README.md
@@ -13,12 +13,12 @@ Shaders for Avidemux with OpenGL support
 - New method based on sensor size and focal length
 - Accurate frame widening
 - Fisheye aware subsampling
-- Rec.709 colorspace conversion _(requires to patch and rebuild Avidemux)_
+- Rec.709 colorspace conversion
 
 #### Content
 
 - avidemux.patch  
-A patch to use GL_NEAREST instead of GL_LINEAR for the luminance channel (the shader is implementing bilinear interpolation with colorspace conversion).
+Optional patch to use GL_NEAREST instead of GL_LINEAR for the luminance channel (the shader is implementing bilinear interpolation with colorspace conversion).
 
 - unfish_gopro_8:7.py  
 Script to compute the parameters
@@ -44,3 +44,9 @@ _For commercial OS's, figure out the paths yourself, then edit the preset to fix
 - Select "Custom/preset_gopro_8:7" in the menu
 - Modify and/or add filters
 - Save the video
+
+#### Shader options
+
+- #define color_conversion: comment out to disable gamma correction for the luminance channel
+- #define texture_filtering: comment out to disable custom bilinear filtering for the luminance channel
+- #define rotate_180: uncomment to rotate the image by 180 degrees