Results

192 by 192 image of Lena was used during testing.
When encoding, the image is converted from RGB to YCbCr.
Symmetry operations are forced on.
Error threshold is set to 100.
The decoding phase is usually repeated 5-6 times.
Below you can find the results from each channel per each phase.

# RGB Y Cb Cr 1 2 3 4 5

The encoding becomes so much faster when RGB to YCbCr conversion is used, because the last two channels become very simple images. The quality does not suffer either because our eyes are more sensitive to intensity versus colour. You can compare the results from RGB and YCbCr encoding below.

RGB YCbCr YCbCr * Images:    Transforms:    7092 2613 4536 Raw bytes**:    15 42 24 Time (ms)***:    16484 5578 10547

* In attempt to make the quality look the same the error threshold has been lowered from 100 to 30 (lower means better quality).
** The original image's raw bytes per transform (higher means better compression).
*** The time it took to perform encoding operation on an AMD Athlon 2500+.

In order to try your own images with different parameters you will have to download the binaries.