Moire Patterns and "Buzz"

Fine patterns are often desirable in print...in video, they will give you a headache. Lines thinner than three pixels will appear to vibrate, especially if they are in motion or fall diagonally. In Photoshop, we create these items to be anti-aliased. In stock photos, you may need to go through and soften these up with the blur or smudge tools. The smudge tool set to darken or lighten mode will isolate your smudging to the dark and light areas, respectively. As this is a timely process to get right (but not overdo) it is a good idea to import the graphic into the NLE and test, or view it on an NTSC or PAL monitor throughout the process.

If your NLE or compositing application has a flicker filter (such as After Effect's Reduce Interlace Flicker effect or Final Cut Pro's Flicker filter) you may choose to skip this step. But remember, a 10-second clip means you are running a filter between 250 and 300 times (depending on video format) versus only one processing pass in Photoshop.

How Fix Moire Photoshop
The fine details in the image on the left will "buzz" or vibrate on-screen. Be sure to soften the image to cut down on this problem.

Fixing Flicker During Scan

If you are scanning in previously printed items, such as newspapers, magazines, books, or inkjet prints, you will likely get a moire pattern. This is caused by Photoshop scanning the small spaces between the previously printed dots. Most scanners have a de-screen filter in their software. If available use it when scanning previously printed items.

Fixing Flicker in Photoshop

If going back to the scan is not an option (or the problem persists), you can try the following options.

• Run the Median filter at a low value (Filter>Noise> Median).

• Run the Motion Blur filter (Filter>Blur>Motion Blur). Run at a value of 1 to 4 pixels at an angle of 90°.

The Median and Motion Blur filters are useful for de-emphasizing details in the image.

Automatic Flicker Fix in Photoshop

If you are using Photoshop CS2 or newer, be sure to load theVideo Actions set from the Actions palette submenu. Within, you'll find the Interlace Flicker Removal action. This applies a gentle but effective flicker removal (and only to the areas that really need it). If you are using an older version of Photoshop, be sure to visit the fine folks at Adobe Evangelists, where you can download the action (http://www.adobeevangelists.com/deflickerator.zip).

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Photoshop Secrets

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