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Pammixinterlace User Manual(0)                  Pammixinterlace User Manual(0)

       pammixinterlace - mix adjacent lines to merge interlaced images


       [-filter={linear, fir, ffmpeg}]



       This program is part of Netpbm(1).

       pammixinterlace is meant to operate on an image which is the interlacing of two images, where raster rows 0, 2,
       4, etc. are from one image and rows 1, 3, 5, etc. are from another.  (See below for why  you  might  expect  to
       encounter such an image).

       pammixinterlace makes each row of the output a mixture of the corresponding row of the input and its two neigh-
       bors.  It uses half of the main row and a quarter each of the two neighbor rows.

       This can be useful if the image is a video capture from an interlaced video source.  In  that  case,  each  row
       shows  the  subject  1/60 second before or after the two rows that surround it.  If the subject is moving, this
       can detract from the quality of the image.

       In video data streams, you often find each frame contains only half the rows of the image -- the  odd  half  or
       the  even  half.  The displayer of the stream displays the rows in their proper positions on a CRT as they come
       in.  When you display the rows in this order, the CRT has less flicker because a particular area of the  screen
       gets  refreshed twice as often.  In the process of capturing such a stream, computers often generate the inter-
       laced image of the type that pammixinterlace works with.  But this interlaced image, when displayed on  a  CRT,
       does  not look the same as if a displayer were rendering the stream directly on a CRT as it arrived, because of
       the timing of when the various pixels get drawn and subsequently fade.  That's why you need something like pam-

       You may prefer the effect of simply extracting one of two images.  You can do that with pamdeinterlace.

              This  option  chooses  between one of the three filtering mechanisms.  linear is a linear-blend formula.
              fir is a size-5 FIR low-pass filter, and ffmpeg is a formula pulled from the documentation of  the  pro-
              gram ffmpeg .

              The default is fir.

              This  option turns on "adaptive" filtering mode.  In this mode pammixinterlace modifies only pixels that
              are obviously part of a "comb" pattern.

       pamdeinterlace(1), pam(1) pnm(1)

netpbm documentation           22 February 2007 Pammixinterlace User Manual(0)