Grayscale Effect for UGUI

Is there any way to apply image effects to the UI (canvas) the same as with a camera? I can apply a grayscale filter to the camera, but my UI is still in color. Is there any way to achieve the grayscale effect for the UI?

This is an older program from before Unity's UI that used a separate UI camera. Now that I've updated to UGUI, I need another way to do the grayscale effect. I'd prefer NOT to have to make duplicate grayscale copies of all the UI graphics.

 

I guess you just have to let your main camera include the UI layer in the culling mask instead of using a separate UI camera.

 

Thanks, but it doesn't work.

I used a separate UI camera when I first created the project using EGUI. Now that it's been updated to use Unity GUI, there is no separate UI camera, which is why I'm having this problem.

Update: I didn't realize I could use a separate camera for the UGUI. I've only ever used screen overlay. That works!