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