This filter will not normally be required except when trying to improve images acquired from pause mode. In some older video equipment there can be a consistant difference in the intensity between the even and odd video fields of an image displayed/acquired in pause mode. The purpose of this filter is to try to determine the nature of any consistant difference in intensity and to correct the image for it by adjusting the intensities of the two fields.
Normally either the Average or Duplicate interlace information filter would be used in preference. However, those two filters discard half the information contained in the signal, whereas this corrective filter does not destroy any information.
Buffer to correct interlace on? Any valid image buffer may be corrected. The buffer filtered will be made the current output buffer. If the buffer specified is in extended memory, then the buffer is first copied to buffer 0; after the filtering is finished, the result will be copied back to the extended memory buffer.
Intensity interlace filter window 1 The information used to adjust the intensity of the two fields is gathered from two user-specified windows within the image. In preference these windows should be chosen on opposite sides of the screen in regions where the variations in intensity are relatively smooth.
The normal method and considerations for specifying a window are relevant. Help with window specification is available through the H help option in the windows submenu.
Intensity interlace filter window 2 The same considerations for the second window apply.
Fit how many terms: 1, 2 or 3 ? Once the difference in the intensity between the two fields has been established, DigImage attempts to fit a constant (1 term), linear (2 terms) or quadratic (3 terms) to this information. The fit is used at the basis of the correction.