Archived posting to the Leica Users Group, 2013/05/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Herbert, I noticed the same with Canon DSLRs - the file size varies depending on the ISO value you use. Cheers Douglas On 08.05.2013 04:50, Bob Adler wrote: > Way beyond my pay grade! > > Sent from my iPad > > On May 7, 2013, at 4:46 PM, Herbert Kanner <kanner at acm.org> wrote: > >> Wanting an inexpensive camera for places/activities that could be risky >> for my M9, I jumped at the offer of a used Lumix DMC-LX5d on the LUG. >> After a dozen hours of learning how to cope quickly with the complex >> array of menus and doing some experemts with RAW, I come up with with >> some puzzlements for the techies among you, >> >> First, for comparison, here is how the M9 files are. Not using Leica's >> compression, the DNG files right out of the camera are exactly 36,4 MB. >> After going into Lightroom (LR4) the DMG files that LR stored from a set >> of twenty or thirty shots ranged in size from 19.2 to 22.2 MB. Clearly LR >> is doing some lossless compression--this started, I think, with LR3; LR2 >> didn't do it. Interesting fact--note this later as you read--is that a >> Mac application called "Just Looking" will display images from RAW files >> and displays both the original and compressed versions equally. >> >> Next, here is the story on the Lumix RAW files. The files right out of >> the camera have ranged in size, again from a moderate set of shots, from >> 11.8 to 11.9 MB. That they are not identical in size is puzzling. Are >> they using some lossy compression from a sensor that puts out larger >> files? Also, I'd like to make a comment on the file size of RAW from this >> 10 megapixel camera. It would indicate that the data from each pixel is >> one byte. Well that is exactly the data size from an M9 if one uses >> Leica's lossy compression, which several LUGers have said is not visually >> detectable. I'm sort of ready to go along with this observation; human >> response to stimuli--all kinds--is logarithmic. That is each time you >> multiply the intensity of a stimulus by a constant factor, e.g., doubling >> it, the human thinks of that as uniform steps (think decibel!). So, the >> Leica 36MB minus whatever the EXIF data consumes is gross overkill!. >> >> Now a funny thing happens when LR turns those files into DNGs. The RAW >> files right out of the camera can be displayed by "Just Looking". But the >> DNG files produced from these by LR cannot. The files produced by LR are >> a bit more varied in size than the originals, ranging from 10.3 to 14.8 >> MB. >> >> Can the techies among you shed any light? >> >> Herb >> >> >> >> Herbert Kanner >> kanner at acm.org >> 650-326-8204 >> >> Question authority and the authorities will question you. >> >> >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > >