Using Winzip 8.1, a single 13.1 MB *ist D .pef file compressed down to 8.5 MB.
Converting the same .pef using the Adobe RAW converter, to an uncompressed .dng resulted in a 11.8 MB file. Dave S On Apr 12, 2005 9:37 PM, Thibouille <[EMAIL PROTECTED]> wrote: > I'd be interested to know how well these RAWs would compress with > either RAR, ACE or 7zip format (best settings of course). > > > On Apr 12, 2005 12:41 PM, Cory Papenfuss <[EMAIL PROTECTED]> wrote: > > > With the 10D, writing RAW format with the camera set to its defaults, I > > > obtain 127 RAW files per a 1G CF card. If I modify the defaults with a > > > custom > > > function and minimize the embedded JPEG file, I can get 143 RAW exposures > > > per > > > 1G card. > > > > > I've corresponded with someone at Pentax and told them they should > > enable/disable the RAW+JPEG function. Basically, either remove the > > full-sized JPEG embedded in the -DS RAW, or make it high enough quality to > > be useful. As it is, it's roughly 1MB... low enough quality to be fairly > > useless, but large enough to waste 15% of the space of the file. > > > > > With the *ist DS, I get 100-105 RAW format exposures on a 1G SD card. > > > > > The *only* variable in how large the -DS RAW files are is how well > > the three embedded JPEGs compress. The RAW data itself is uncompressed > > (although packed), 12-bit Bayer data. > > > > > So the Canon will store 27-43% more RAW exposures per 1G card. While this > > > is > > > a useful improvement in space efficiency, I don't really consider that > > > significant. Yeah, sure, I need 3 1G SD cards for the DS compared to 2 1G > > > CF > > > cards for the 10D, but they're cheap enough as to not be that much of a > > > burden nowadays. I don't often need more than one 1G card anyway, unless > > > I'm > > > traveling. > > > > > Aside from a bit of computational issues, there's no reason not to > > compress the RAW data. There could even be a "compress all now" you could > > use to "pack" the files on the flash card and make more room if it was too > > slow to do on the fly. Unlikely, though, given how slow flash memory is. > > It'd probably be faster to compress on the fly and spool to the card than > > to just spool the uncompressed onto the card. I think Pentax was just a > > bit behind on the design schedule and had to let something slip... sorta > > like USB-2.0 lacking on the -D. > > > > Just for a datapoint, I took 25 -DS RAW files and compressed them > > losslessly with a couple of different methods: > > > > 249355733 bytes uncompressed (Full size, 9.5MB avg) > > 209182171 bytes compressed with 'gzip' (84% original size, 8.0MB avg) > > 209185296 bytes compressed with 'zip' (84% original size, 8.0MB avg) > > 158154181 bytes compressed with 'bzip2' (63% original size, 6.0MB avg) > > > > A few of those pictures probably compress a bit better than > > most, since they were pictures taken out of my airplane (lots of sky, > > clouds, haze). Even with that, they could certainly be compressed to > > roughly 1MB/Mpixel, but it would take firmware work, and winders/mac > > software work. > > > > -Cory > > > > ************************************************************************* > > * Cory Papenfuss * > > * Electrical Engineering candidate Ph.D. graduate student * > > * Virginia Polytechnic Institute and State University * > > ************************************************************************* > > > > > > -- > ---------------------- > Thibouille > ---------------------- > Z1,SuperA,KX,MX,P30t and KR-10x ... > >
