
x Xtag for chroma subsampling mode
x document Xtag in manpage

x Error message for "cannot make progressive from interleaved" should 
  suggest using 'ilace=XXX_only' modes.

o 7-9 tap Lanczos-windowed sinc kernel
x independent kernels for X and Y scaling

- Instead of simple matte-padding of off-frame pixels (for large kernels),
   do proper tiling --- tile the matte+frame, as bounded by the projection
   of the target back to the source.
  (i.e. Source size is the tile size, even though some of the tile may be
   filled with matte.)
  [hmm... on second/third thought, this is probably unnecessary and a poorer
   way to do it anyway.]

o Fix subsampling for NTSC DV  ---- horizontal shift in chroma.
  [...unless Poynton's book is *wrong*.]

- Fix the rounding errors in scaler-matto fixed-point calculations:

x   1)  Negative doubles should get "- 0.5" to round properly when
        being converted to fixed-point.
x   2)  When unfixing, stuff with ">>(2*FSHIFT)" should have had an
        offset of "(1<<(2*FSHIFT-1))" pre-applied, *not* "2*(1<<(FSHIFT-1))"
        (i.e. *not* just "2*FHALF").
-   3)  Shouldn't negative fixed-point quantities, like <128 chroma samples,
        get rounded inward (upward), not downward?  (When UNFIXing after
   	the convolution)
       [not right now --- would make UNFIX op much slower?]

  (See if these fixes have any affect on the chirp tests....)

x Warn about chroma-mangling when casting interlaced input to progressive,
   when chroma is vertically subsampled.  (But TOP_ONLY or BOTTOM_ONLY is ok.)

x Warn about chroma-mangling when casting progressive input to interlaced,
   when chroma is vertically subsampled.

x Warn/Inform when fake progressive mode being used.

x Both read and write streams in extra chroma ss modes.

x Add more presets:  DVD_WIDE, DV, DV_WIDE

o non-fake ilace options should undo preceding fake ilace options.

x let active region geometry strings use framesize as a default region size,
   so that one can specify "active=+4+0" to just do shifting.

o fix bug:  box kernel coefficients are not correctly normalized.

o fix bug:  coefficients with two maximum should share any norm correction

x recognize other XXX:1001 framerates as NTSC norm (and similar for PAL).

x add CVD preset

x (add note to aspect webpage about pedantic square pixel issues.)

x display more/better info about scaler engine configuration to user.

o add 'blur' option to scaling engine.

o change default scaler options to high-quality sinc.

o check the behavior of kernel support calculation in scaler-matto.C
   ...currently, 'supp' refers to 1/2 of support (one side or other);
      perhaps calcs should deal with 2.0*supp instead, to alleviate
      rounding down too much???

o add presets for (S)VCD stills which accounts for overscan...
  (perhaps do same for DVD/etc... "full-frame" mode?)
   -O preset=VCD_STILL,hi,ovscan:10%
   -O preset=SVCD_STILL,lo

o add "-O dar=XXX:YYY" option; calculate SAR from framesize + DAR.
