Custom Wipe Using a Bitmap Image In this tutorial, you ll create a custom wipe using a bitmap image as the template. You can use the pixel information of an image to create many different types of wipes. This tutorial will only show you a few, but once you ve learned the technique, you can experiment on your own. 1 of 15
Capturing Media and Setting Up the Shot 1. Create a new sequence with the following settings: Video Format: NSTC D1 4/3 Resolution: Full/Uncompressed 2. Import the following media files using the capture settings shown here: Clouds.mov Man.mov 3. Place the Man clip on the timeline and make it 1 second long. 4. Place the Clouds clip right beside the Man clip on the timeline. 2 of 15
Applying the Transition 1. Select the edit point between the two clips and apply an Effects Tree transition by choosing Apply Effects > Effects Tree from the Image Tools toolbar. 2. Make sure the selected edit point is set to Start and that the duration of the transition is 30 frames. 3. Expand the tree and add the Dissolve effect as shown here. 4. Play back the effect to view the simple dissolve. 5. Open the Dissolve property editor and switch to the Timing property page. 3 of 15
6. Select both keyframes and delete them. This will keep the dissolve at 100%, which creates a simple composite where Input 2 (Clouds clip) is composited over Input 1 (Man clip). 4 of 15
Using an Image as the External Matte 1. Add a Fractal Noise effect (Source Generators folder) to the tree as shown here. The Fractal Noise effect will be used as the external matte. 2. Open the Dissolve property editor, switch to the Masking property page, and set the Matte Input to Luma. 5 of 15
3. Add a Threshold effect to the tree as shown here. The Threshold effect splits the RGB channels into their black and white components. 6 of 15
Animating the Threshold Values 1. Open the Threshold property editor. 2. Go to the first frame of the effect by clicking the Previous Key button. Previous Key Next Key Set/Remove Key 3. Set the Minimum and Maximum values to 100 and set a keyframe by clicking the Set/Remove Key icon. 4. Go to the last frame of the effect by clicking the Next Key button. 7 of 15
5. Change the Minimum and Maximum to 0 and set another keyframe. 6. Right-click on the Set/Remove Key icon and choose Linear from the menu. Avid DS interpolates between the two clips in a linear manner. 7. Scrub through the effect to view the result. 8 of 15
Softening the Edges 1. Add a Blur effect to the tree as shown here. The edges of the fractal noise patterns are softened. 2. Open the Blur property editor and set the X and Y Radius to 20. 9 of 15
Alternative Method : Using Input 2 as the External Matte 1. Remove the Fractal Noise node from the tree and connect the Input 2 node to the Threshold node as shown here. 2. Scrub through your effect. The white parts of the Clouds clip start to appear first, and then, over the course of the dissolve, the darker parts of the image appear. Note: You can use Input 1 as the external matte instead of Input 2. In this case, the clouds will appear over time based on the luminance values of the Man clip. 10 of 15
Removing Edge Artifacts The Threshold effect works by clipping individual RGB channels to either pure black or white. Since these channels are not identical, artifacts may occur in the areas where they differ. Here s a quick way to remove them. 1. Right-click on the Threshold node and choose Open Viewer from the menu. This displays only the threshold effect applied to Input 2 in a floating viewer. 2. Scrub through the effect. Notice how saturated the edges are. 3. Add a Color Correction effect to the tree as shown here. The Color Correction effect will be used to remove the saturated edges created by the Threshold effect. 11 of 15
4. Open the Color Correction property editor and set the Saturation to 0. The image is set to black and white, which removes the saturation-related artifacts. 5. Close the floating viewer. 6. Scrub through the effect to make sure the effect as a whole, gives you satisfactory results. 12 of 15
7. Process the effect. 8. Play back your sequence when the processing is complete. Note: If you want to reveal the darkest parts of the image first, open the Dissolve property editor and change the Mask Input from Luma to Luma:Invert. You ll also have to reverse the animated curves for the Threshold effect. You can also use a third clip as an external matte, but to do so, you would have to use the Effects Tree in the Compositing layout, since creating a dissolve from a clip effect only has two inputs. 13 of 15
What s Next This effect works by changing a grayscale image to pure black and white, and using it as an external mask for a composite. If you animate the threshold of this mask, you can reveal the image over time. This technique is useful for creating different kinds of wipes, such as: A regular left-to-right wipe A diamond-shaped wipe A triangular-shaped wipe A clockwise radial wipe You can create your own templates in either.bmp or.tiff format, and store them in the Test Patterns folder for quick access: F:\Program Files\Avid\DS_v4.0\DSSystem\VideoBitmaps\TestPatterns\NTSC or F:\Program Files\Avid\DS_v4.0\DSSystem\VideoBitmaps\TestPatterns\PAL. 14 of 15
Any new patterns you create will appear in the Pattern list. 2001 Avid Technology, Inc. All rights reserved. Avid and the Avid DS logo are registered trademarks of Avid Technology, Inc. All other trademarks contained herein are the property of their respective owners. 15 of 15