# Last edited on 2011-05-09 05:49:37 by stolfi

UNPACKING

  Used two commands:
  
    ffmpeg -i video.m1v -ss 5 -t 6 -vcodec png frames/%08d.png
    
  Obtained 180 frames (00000001.png to 00000181.png).
  Deleted 67--92 and 102--110, too much camera motion blur.
  
COMPOSITING

  Trying to align successive frames by hand. Let's pick some frames 
  
    mkdir frames-p
    frames=( 0000000{1,2,3,4,5,6,7,8,9} )

    for f in ${frames[@]} ; do 
      bfile="frames-b/${f}.png"
      pfile="frames-p/${f}.ppm"
      convert ${bfile} ${pfile}
    done
    
    ( cd frames-p && display -title '%f' ${frames[@]/%/.ppm} ) &
    
  Created a file frames-p/points.txt with 
  the pixel coords of 4 reference points
  fo each of those frames.
  
  Splittin that file into separate files frames-p/${f}.pts:
  
    ( cd frames-p && \
      cat points.pts \
        | gawk \
            ' //{ 
                n = $1; fn = (n ".pts"); 
                printf "%s\n", substr($0,9) > fn;
                close(fn); 
              } 
            ' \
    )

  Checking the placement of the reference points:
  
    for f in ${frames[@]} ; do 
      pfile="frames-p/${f}.ppm"
      ppts="frames-p/${f}.pts"
      ofile="frames-p/${f}-g.png"
      pt=( `cat ${ppts}` )
      convert ${pfile} \
         -stroke Yellow -fill None \
         -draw "polygon ${pt[0]},${pt[1]} ${pt[2]},${pt[3]} ${pt[4]},${pt[5]} ${pt[6]},${pt[7]}" \
         ${ofile}
    done
    ( cd frames-p && display -title '%f' ${frames[@]/%/-g.png} ) &

  Pick a reference frame ${ref} and apply a projective map
  correction to all frames to match is reference points:
  
    ref=00000005
    rpts="frames-p/${ref}.pts"
    for f in ${frames[@]} ; do 
      pfile="frames-p/${f}.ppm"
      ppts="frames-p/${f}.pts"
      ofile="frames-p/${f}-a.ppm"
      pnmprojmap \
          -points `cat ${ppts}` `cat ${rpts}` \
          -interpolate 0 \
          -oSize 900 600 \
          -oOrg 90 60 \
          -maxval 65535 \
          ${pfile} \
        > ${ofile}
    done
    ( cd frames-p && display -title '%f' ${frames[@]/%/-a.ppm} ) &
    
  The alignments were not spectacular. I must write a multi-image
  alignment program that combines a projective map with a
  low-frequency harmonic series distortion.

  Let's try mixing the corrected images anyway:
  
    pnmxarith -mix 0.50000 0.50000 frames-p/00000001-a.ppm frames-p/00000002-a.ppm > .a12.ppm
    pnmxarith -mix 0.50000 0.50000 frames-p/00000003-a.ppm frames-p/00000004-a.ppm > .a34.ppm
    pnmxarith -mix 0.50000 0.50000 frames-p/00000005-a.ppm frames-p/00000006-a.ppm > .a56.ppm
    pnmxarith -mix 0.50000 0.50000 frames-p/00000007-a.ppm frames-p/00000008-a.ppm > .a78.ppm
   
    pnmxarith -mix 0.50000 0.50000 .a12.ppm .a34.ppm > .a1234.ppm
    pnmxarith -mix 0.50000 0.50000 .a56.ppm .a78.ppm > .a5678.ppm
    
    pnmxarith -mix 0.50000 0.50000 .a1234.ppm .a5678.ppm > .a12345678.ppm

    pnmxarith -mix 0.11111 0.88889 frames-p/00000009-a.ppm .a12345678.ppm > .atot.ppm
    
    convert .atot.ppm .atot.png
    
    gimp .atot.png &
    
  The result is not bad! 
  
  Removing the low-frequency components with fft:
  
    pnmfftfilter -kill -from 120 -verbose .atot.ppm > .ahip.ppm
    convert .ahip.ppm frames-b/avg-001--009.png
    display frames-b/avg-001--009.png &