Archived posting to the Leica Users Group, 2013/05/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]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