BUGS:
-----
- Doesn't always give perfect reconstruction with binsize = 0.


PROGRAM IMPROVEMENTS:
---------------------

- Allow non-square images.  These are currently not accepted, because
  of in-place transpose in collapse_pyr.c.

- Provide an option to use orthogonal wavelet filters, such as the
following 9-tap kernel:
 [0.02807382 -0.060944743 -0.073386624 0.41472545 0.7973934
    0.41472545 -0.073386624 -0.060944743 0.02807382]

- pipes: should be able to read from/write to stdin/stdout.

- Provide a silent (quiet) mode with -q flag.

- color images: provide rgb->yiq, yiq->rgb

- allow progressive transmission (i.e., reconstruct low-res image, and
  then gradually add in detail).


CODER IMPROVEMENTS:
-------------------
- Choose quantization binsizes adaptively for each subband.

- Is there a more efficient run-length coder?

- Use an arithmetic coder, instead of run-length and/or huffman.

- Use Vector Quantization.

- Use nonlinear prediction to guess the high-frequency subband
  coefficients given the low-frequency subbands.
