Fixing Line Problems in Video Images

Some video capture devices actually take two sequential images, or fields, and combine them to form the final image. The first field captures the even rows of the image. A very short time later, the process repeats, but this time the odd lines are captured. These two fields are combined by interleaving the lines of the two fields, producing the final frame. But since the two fields are captured at slightly different times, it's possible that the subject may have moved during the interval. This produces images with undesirable striping. This type of defect is more likely to happen when motion is involved, either by objects that are moving in the scene, or by moving (or panning) the camera.

The Deinterlace command remedies this problem by discarding either the even or the odd lines of the image, and then making replacements by interpolating the retained lines.

Note: Apply the Deinterlace command before you resize the image. Resizing adds or removes pixels from the image, which makes it more difficult to determine scan lines.

If your image has already been resized, you must return it to as close to the original size as possible so that each scan line is one pixel high. Zoom in until you can see individual pixels to determine how many pixels make up one scan line, and then resize the image so that each scan line is one pixel. For example, if the enlarged image has scan lines that are two pixels high, you would resize it by 50 percent. Keep in mind that the image loses clarity when you resize it.

To deinterlace an image:

  1. Make sure the image has no selections. If necessary, choose Selections > Select None. The Deinterlace command is not available if the image contains a selection.

  2. Choose Adjust > Add/Remove Noise > Deinterlace.

  3. In the preview window, center the area of the image where the scan lines are most apparent.

  4. For Scanlines to retain, select either Odd or Even to determine whether the odd-numbered or even-numbered scan lines are kept.

  5. Click OK.

Related Topics

Removing Image Defects and Noise

Removing Artifacts from JPEG Images

Removing Undesirable Patterns in Scanned Images