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  • Writer's pictureGavin Whittaker

"Walking the Edge: Unleashing the Magic of Edge Extend Techniques!"

Welcome to the wild world of edge extend techniques! In this thrilling adventure, we'll explore the different approaches to edge extension, their pros and cons, and when to use them in your compositing journey. So buckle up, and let's dive right in!

NOTE this information is curated from the amazingly informative video by Sebastian Schutt

The Edge Extend Lineup

There are several edge extend techniques that can help you get rid of those pesky bright or dark edges while preserving as much detail as possible. Let's meet our contenders:

  1. Blur | Unpremult: This technique uses blurring and unpremultiplying to spread out pixel values, making it great for soft edges. Check out this video tutorial on Blur | Unpremult.

  2. Vector Extend: Stretching pixels out perpendicular to the surface, this method maintains details and sharp lines, perfect for streaky motion blur. Watch this video tutorial on Vector Extend.

  3. Erode | Dilate: This combo erodes the image inwards and then dilates it back out, replacing unwanted edges with more valid information. Learn more in this video tutorial on Erode | Dilate.

  4. Paint | Smear: A manual approach that gives you full control over how pixels are stretched out, ideal for selective areas. See this video tutorial on Paint | Smear.

Pros and Cons Showdown

Each technique has its own strengths and weaknesses. Let's break them down:

Blur | Unpremult


  • Quick, simple, and fast

  • Works well for soft edges


  • Loses detail when dealing with thicker edges

  • Not ideal for maintaining sharp details across edges

Vector Extend


  • Maintains details and sharp lines

  • Better for streaky motion blur or thin bright/dark edges


  • More complex setup

  • May require additional tweaking for optimal results

Erode | Dilate


  • Replaces unwanted edges with more valid information

  • Can be customized with different filtering algorithms


  • Alters the image overall, requiring selective merging

  • May lose some plate detail

Paint | Smear


  • Full control over pixel stretching

  • Ideal for selective areas or when other techniques aren't sufficient


  • Time-consuming

  • Not suitable for large areas or numerous frames

When to Use Each Technique

Now that we know the pros and cons, let's discuss when to use each technique:

  • Blur | Unpremult: Best for soft edges or when you need a quick and simple solution.

  • Vector Extend: Ideal for maintaining sharp details across edges, dealing with streaky motion blur, or thin bright/dark edges.

  • Erode | Dilate: Useful when you need to replace unwanted edges with more valid information and can selectively merge the results.

  • Paint | Smear: Perfect for selective areas where full control is needed or when other techniques aren't sufficient.

And there you have it! A fun and informative exploration of edge extend techniques. Remember, the key to success is understanding each technique's strengths and weaknesses and choosing the right one for your specific shot. Now go forth and conquer those edges! 🚀

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