On Feb 25, 2006, at 1:48 PM, John Francis wrote:
That said, since these cameras can do JPEG compression, I'm sure
there's enough processing power to do lossless RAW data compression
through a variety of algorithms. It's really a matter more of
buffers, speed, etc.
I'd guess that the JPEG compression is done with dedicated silicon,
rather than general-purpose hardware and firmware.
I'm pretty sure of that too. The JPEG image processing engine takes
the input parameters from the user controls and spits out a JPEG. No
reason you couldn't do the same thing with a lossless Lempel-Ziv or
even Huffman compression (or other) algorithm on the RAW sensor data,
just put the compression engine into cheap firmware.
I could be wrong,
in which case I'd agree with you that there's more than enough power
there to implement a simple data compression scheme. In fact that
might even result in a higher RAW frame rate - what you lose in the
compression time may well be more than paid back in the reduction
in I/O time for the smaller file size.
The tradeoff is in buffer space, bus speeds, marketing requirements
for user perceivable performance and cost. The hardware to do this is
getting cheap enough that it should be achievable in a $1500 body,
presuming that Pentax feels there's an adequate need. With storage
cards becoming so large and so fast ...
Godfrey
