The interlace information may be duplicated in a manner similar to D (below) using this option. However, instead of a single odd line being duplicated into the even lines (or vice versa), the average of the two nearest odd lines is used.
This option computes the mean and RMS intensities of the even lines and the odd lines (separately) for the region of the image lying within the window. This information is returned to the user and may be used to determine whether it is necessary to interlace filter the image or reacquire it.
Either duplicate the even numbered video lines into the odd numbered lines, or vice versa. The duplication may be either within a window or the entire buffer. Duplication of interlace lines may prove necessary in either of two situations: if the buffer was acquired from freeze frame on a VTR; or if the motion is sufficiently rapid that the 1/50s or 1/60s time delay between the two halves of the interlace contaminates the image. Duplicating the interlace reduces the vertical resolution from 512 to 256 lines.
THIS FILTER IS NO LONGER INCLUDED IN THE MAIN DigImage MODULES. IT IS STILL ACCESSABLE TO THE DEVELOPMENT SYSTEM (SUBROUTINE CorrectIntensityInterlace(..)). This filter works by fitting a function to the curvature the 'odd' lines see and the curvature the 'even' lines see. These curvatures will be dominated by any mismatch in intensity due to video interlace. The difference in these two curvature functions is then used as the basis of a correction in the intensity level. Data for the functions is obtained from two user specified windows. The correction is applied to the whole frame buffer. Typically this filter will be used only when the signal quality is relatively low. Frequently it would be preferable to simply duplicate interlace lines using option D.
THIS FILTER IS NO LONGER INCLUDED IN THE MAIN DigImage MODULES. IT IS STILL ACCESSABLE TO THE DEVELOPMENT SYSTEM (SUBROUTINE CorrectVerticalInterlace(..)). This filter works by looking how two (preferably straight) lines in the image are distorted by the misalignment. The user sets up two windows, one containing each line, specifies a threshold level and whether a low-high or high-low (left to right) transition defines the line. The correction is then calculated from functions fitted to the 'odd' line and 'even' line curvatures in a manner similar to that used for I. The correction is applied to the whole buffer. Typically this filter will be used only when the signal quality is relatively low. Frequently it would be preferable to simply duplicate interlace lines using option D.