Re: Prediction in differencing pixels with the left neighbour.

On 8 Gen, 15:19, danilobrambi...@xxxxxxxxxx wrote:
Hi all,

given a single channel of an RGB24 image (say green), I compute for
each pixel the difference with the previous one (starting from the top-
left to the lower right). Can anyone point me to a algorithm to reduce
errors by prediction of the next step?

Thank you all!

Well, at the moment I am working on lossless compression. Wavelets and
Curvelets seems to be quite too complex for my needs. I am not
intended to reach state of the art image compression levels, just
coding for fun. I would prefer on a simple, clear and fast algorithm
than a complex one. My algorithm now uses simple technics like channel
differencing, neighbour pixels comparison, Rice encoding and Move to
Front. I can compress images near Photoshop HP JPEG-LS plugin can do
using very small amout of memory, and can beat JPEG-LS in a few ones,
but I am not using any kind of prediction right now so I hope to fill
the gap in this way.

So, as sayid before I compute for each pixel the difference with the
previous left one (starting from the top-left to the lower right),
then encode residuals. Is there any simple algorithm that can help me
to predict the next pixel, say given the very near past ones, to
reduce residuals?
For example, I tryied to compute average between the current residual
and the last one, using it as an 'error correction' for the next step,
but It doesn't work well on all images. It makes complex images
smaller (ok here) but tends to increase size of images that already
compress well without any prediction (so it increase errors, not
reduce them)

Thank you for help! :-)
.

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