Interlacing

This window helps you fix problems surrounding interlacing, a common phenomenon in pictures obtained from video.

Digital cameras and other video equipment work, for historical reasons, with interlaced pictures. Such picture contain two "fields"—half-pictures—that can each come from different scenes, especially if the source video sequence contained a large amount of motion. The first field is stored in the odd rows of the picture; the second field is stored in the even ones. lf the scene is static, without movement, then the picture has full resolution, and no deinterlacing is needed. (The same applies for pictures taken from classical film video, which also usually contains two fields in each picture.) If the scene changes fundamentally between frames, then the picture will contain two fundamentally differing fields. The vast majority of camera stills are somewhere inbetween: some parts are moving; others, static.

Use Edit | Adjust | Interlacing… in the Browser window or Adjust | Interlacing… in the Editor window to reach the Interlacing window, or press [Ctrl+Shift+L].

Zoner Photo Studio can help you adjust and fix photos containing interlaced fields. Different methods are the right solution for different pictures—sometimes you will want to only deinterlace a part of a picture; sometimes you will even want to use different (de)interlacing tools for different part of a picture!

• Blended clipping—this method is the one generally recommended. It tries to intelligently join both fields in areas without motion, so as to increase the picture's final resolution. In areas with motion, the program needs advice on a "preferred" field that should be kept (and the other thrown out).
• Blend fields—this method joins both fields into one picture. In places with motion, the picture will be "double" and blurry.
• Interpolate field—only the preferred field will be used for calculations; the other field is thrown out and replaced with lines determined via interpolation.
• Duplicate field—only the preferred field will be used for calculations; the other field is thrown out and replaced with lines determined via duplicating lines from the preferred field.
• Subsample field—only the preferred field is used. Instead of filling in lines between it, it is shrunk using interpolation (subsampled), so that the ratio of sides in the final picture remains correct. The resulting picture will have 1/4 the resolution of the original.
• Swap fields—This method is not a deinterlacing method at all. It swaps the two fields instead. This is useful because some programs erroneously save fields in the opposite of the correct order. Swapping solves this.

The Prefer first field checkbox sets which of the two fields is the "preferred" one. The right setting for this checkbox will vary from case to case.

Joining threshold—this sets the minimum amount of difference that is judged to be motion when you are using Blended clipping. If you set it too high, then blended clipping may not catch and remove all interlacing artifacts in the picture. If you set it too low, you will effectively be needlessly reducing the picture's resolution, because more of the non-preferred field will be thrown away and replaced via interpolation than is necessary. We recommend values from 10 to 25.

Test brightness, not color—motion detection when using Blended clipping is based on differences in either color or brightness for each pixel in the first and second field. Detection based on color is most useful for drawn pictures or other scenes with large areas of one color (above all animated films). Brightness-based detection works well for parts of a picture with transparent elements (like television graphics, or logos).