
Applying effects to parts of a graphic
The Blend With Mask filter can be used for many cool and useful effects. It allows you to mix two images (photos, movie clips, drawings, text etc) and use another image as mask for which image to display for each pixel. One common use of it is to apply an effect (eg blur, color adjustment) to only a part of the image.
Here's an example of how you might set up the filter nodes to get a gradual blur effect over the source image:
To apply an effect to a part of an image:
- First decide wether you want to do this for only a clip, or for a whole track. See Clips vs Tracks.
- Select a clip or track by clicking it in the Timeline or in the movie canvas. It can be any kind of graphic (eg photo, video, text).
- Find the effect you want to apply to your image in the media browser (eg Gaussian Blur) and drop it just below the top node.
- Find the filter Blend With Mask in the Media Browser.
and drop it below the previous effect node (eg Gaussian Blur).
- The Blend With Mask filter takes 3 images as imputs: Background Image, Image and Mask Image. Some default images was be set when you dropped the filter, but they can be replaced by dropping other image on the nodes or by reconnecting the lines that connect the different nodes. We want to set the filter effect (eg Gaussian Blur) as Image. To do that you drag from the middle round little button at the top of the Blend node to the filter node.
- Connect the Image attribute to the source graphic by dragging from the leftmost little round button on the Blend node to the top node
- Now parts of the image are blurred (or whatever effect you selected). We can now replace the Mask Image by dragging some other image and dropping it on the Mask Image node. The image can be any photo, video or graphic you want. In dark areas of it the pixels will be as the background image and in light areas as the filtered image.
See also
The Apple reference documentation
The Media Browser
Adding Filters
Clips vs Tracks