LouK Posted October 22, 2011 Share #1 Posted October 22, 2011 Advertisement (gone after registration) Has anyone compared the results shooting the M9 in RAW compressed and uncompressed? When will there be an advantage to shooting uncompressed? 1 Quote Link to post Share on other sites More sharing options...
Advertisement Posted October 22, 2011 Posted October 22, 2011 Hi LouK, Take a look here DNG Compression, Any Difference in Quality?. I'm sure you'll find what you were looking for!
mjh Posted October 22, 2011 Share #2 Posted October 22, 2011 (edited) Three out of many more threads covering this topic: http://www.l-camera-forum.com/leica-forum/leica-m9-forum/148456-compress-not-compress.html http://www.l-camera-forum.com/leica-forum/leica-m9-forum/134248-compressed-uncompressed.html http://www.l-camera-forum.com/leica-forum/leica-m9-forum/101279-compressed-versus-uncompressed.html The debate is in its fifth year now and so far, nobody has made a convincing case for the superiority of the uncompressed format. Edited October 22, 2011 by mjh Quote Link to post Share on other sites More sharing options...
250swb Posted October 23, 2011 Share #3 Posted October 23, 2011 The debate is in its fifth year now and so far, nobody has made a convincing case for the superiority of the uncompressed format. Each year newer software is released by the likes of Adobe etc. which turns on its head what can be acheived with a file. People have hamstrung themselves by deleting files that they think are too noisy, only for vastly better noise reduction software to be introduced. Soon all those images showing camera shake will perhaps have some merit and become sharp, if you haven't already deleted them. So in the future who knows what benefits an uncompressed file will give over a compressed one, except as the great Mario Andretti once said about how to beat others on the track 'there ain't no substitute for cubic inches'. Steve Quote Link to post Share on other sites More sharing options...
jaapv Posted October 23, 2011 Share #4 Posted October 23, 2011 With present and future computer processing power and ever larger and ccheaper memory there is no reason at all to compress the files- and one might want the information lost ( Leica's compression is amazingly good but not lossless) in the future as postprocessing software progresses. Quote Link to post Share on other sites More sharing options...
mjh Posted October 23, 2011 Share #5 Posted October 23, 2011 Each year newer software is released by the likes of Adobe etc. which turns on its head what can be acheived with a file. People keep repeating this argument year after year. There is a deeper reason why it hasn’t come true: The information supposedly lost in the lossy compression scheme was never there in the first place. It is data that is lost, not information. And while high capacity memory cards and hard disks get cheaper all the time, the M9 won’t get any faster at storing uncompressed DNG files. Maybe the M10 will be faster, but then the M10 may also support lossless compression – and it might create enough information per pixel to actually warrant a lossless compression scheme. 2 Quote Link to post Share on other sites More sharing options...
sblitz Posted October 23, 2011 Share #6 Posted October 23, 2011 my understanding is that the uncompressed dng file contains certain colors in the blue spectrum that monitors and printers cannot replicate -- and the eye cannot really see. i was using uncompressed and when this was explained to the class at a recent leica akademie in nyc i switched back to compressed files. the only one who is unhappy is the guy who sells me the 8mb cards, need half as many 1 Quote Link to post Share on other sites More sharing options...
t024484 Posted October 23, 2011 Share #7 Posted October 23, 2011 Advertisement (gone after registration) The information supposedly lost in the lossy compression scheme was never there in the first place. It is data that is lost, not information. The image information is kept within the the data, so if you lose data, you lose information. The Leica Compression results in adding noise to the information. The amount of added noise though is under the level of perception for the human eye. So I agree that no future version of PS or whatever program will bring any benefit. my understanding is that the uncompressed dng file contains certain colors in the blue spectrum that monitors and printers cannot replicate -- and the eye cannot really see[/Quote]There are no colors effected or deleted by compressing DNG files. The Image just becomes just a tiny bit noisier and only at low ISO values (0,2 stops at ISO 160). At ISO values above 640, other sources of noise are dominating Hans Quote Link to post Share on other sites More sharing options...
250swb Posted October 23, 2011 Share #8 Posted October 23, 2011 It is data that is lost, not information. . You could well be right. But on the basis that I don't like recommending things that may or may not affect the eventual outcome way down the road of other peoples photographic success's (as opposed short term results), I would rather recommend 'better safe than sorry'. If you have a more succesful strategy than 'better safe than sorry' I'm sure the world would be happy to share with you? Steve 2 Quote Link to post Share on other sites More sharing options...
mjh Posted October 23, 2011 Share #9 Posted October 23, 2011 If you have a more succesful strategy than 'better safe than sorry' I'm sure the world would be happy to share with you? ‘Better safe than sorry’ is a great strategy whenever one isn’t really sure. Only in this case I am. Quote Link to post Share on other sites More sharing options...
LouK Posted October 23, 2011 Author Share #10 Posted October 23, 2011 To MJH, thanks for those links. I found this statement at one of them: "1/ generally speaking, up to ISO 640 it's best to use uncompressed DNGs 2/ at ISO 640 and higher, there's no benefit in using uncompressed DNGs - use compressed and save time and storage space. 3/ if storage / processing speed is a serious issue and you're really confident about exposure, then compressed DNGs can give good results (but you're losing quality and wiggle room at lower ISO values) 4/ using the "Convert to DNG during import" option in Lightroom makes sense with any Leica DNGs as its lossless compression reduces system overheads for processing." I am going take some of my own shots and if I learn anything new I will share with you all. The one area I do not see mentioned is the effect when cropping. I am curious to see how compressed and uncompressed files are affected by cropping. I would imagine that depending on the amount of the crop, the ability to make large prints is diminished. Quote Link to post Share on other sites More sharing options...
pop Posted October 23, 2011 Share #11 Posted October 23, 2011 It is data that is lost, not information. How do you back that statement? Can you convincingly demonstrate that the discarded data was not generated by the sensor as a result of converting the light projected as image into bits? If you can do that, then it's clear that the data is spurious and ought to be dropped from the image data. If you can not, then your statement is in error and should read "you're not likely to miss the data". 1 Quote Link to post Share on other sites More sharing options...
farnz Posted October 23, 2011 Share #12 Posted October 23, 2011 How do you back that statement? ... Redundancy? Suppose that you're capturing in 16-bit words but in some parts of the image there is only enough information to fill a 12-bit word, for instance where highlights have clipped, then the remaining four bits would be populated with redundant data to maintain the 16-bit format. Losing this data would not lose information. The above is purely hypothetacal and, I accept, quite possibly flawed but is included for illustration. Pete. Quote Link to post Share on other sites More sharing options...
kdriceman Posted October 24, 2011 Share #13 Posted October 24, 2011 To MJH, thanks for those links. I found this statement at one of them: "1/ generally speaking, up to ISO 640 it's best to use uncompressed DNGs 2/ at ISO 640 and higher, there's no benefit in using uncompressed DNGs - use compressed and save time and storage space. 3/ if storage / processing speed is a serious issue and you're really confident about exposure, then compressed DNGs can give good results (but you're losing quality and wiggle room at lower ISO values) 4/ using the "Convert to DNG during import" option in Lightroom makes sense with any Leica DNGs as its lossless compression reduces system overheads for processing." I am going take some of my own shots and if I learn anything new I will share with you all. The one area I do not see mentioned is the effect when cropping. I am curious to see how compressed and uncompressed files are affected by cropping. I would imagine that depending on the amount of the crop, the ability to make large prints is diminished. I don't see any reason to compress my DNGs. I have plenty of processing power, plenty of storage and it doesn't seem to have a meaningful effect on the in-camera write speed. Quote Link to post Share on other sites More sharing options...
pop Posted October 24, 2011 Share #14 Posted October 24, 2011 ... capturing in 16-bit words but in some parts of the image there is only enough information to fill a 12-bit word, for instance where highlights have clipped This is not quite how it works. The sensor cell registers photons. If there are no photons at all (or rather, if the number lies below a threshold) then the cell will report "blackness". If the number exceeds another threshold, the cell will report "maximum detectable brightness" (or with luck, "result unreliable, clipped"). Now it all depends on how accurately the sensor cell can discern the number of photons caught during exposure. In a reasonable camera it will do so to an accuracy of 12 bits or even 16 bits. If the accuracy (the number of bits) delivered by the sensor is meaningful and not simply an artifact, then dropping bits from that data will destroy information. Think "strictly monotonously growing", if such exists in English. This applies only to parts of the image which are properly exposed. Over- and underexposed portions do not reflect an accurate count. Quote Link to post Share on other sites More sharing options...
dwbell Posted October 24, 2011 Share #15 Posted October 24, 2011 (edited) Just as another aside to the "what if processing down the line" argument. Honestly, my shots that were crap on the Fuji S602 are still crap in Lightroom 3. Some (well, two actually) shots from my canon 300D (Digital Rebel in the US?) are way better than anything I've shot with the cameras since including the 5DII and the M9. I haven't "re-processed" them in LR3, they're not better due to the algorithm used to suppress the noise or de-blur the blur, they're better photographs period. I'm always against the "photography is more than technology" arguments in this forum, which is specifically abut one technical tool. But I have never, in 12 years of digital photography gone back and found an absolute GEM in my archives that was only a lump of coal due to the software available at the time. YMMV of course! PS - I shoot compressed. It is what it is. It's not as "good" as MF files, it's "better" then the 30D was. If you nailed THE shot of your life, of your generation, that changed the world as we know it, that ended poverty in a single image - would it do more if it was uncompressed? Edited October 24, 2011 by dwbell PS 2 Quote Link to post Share on other sites More sharing options...
vanhulsenbeek Posted October 24, 2011 Share #16 Posted October 24, 2011 If you nailed THE shot of your life, of your generation, that changed the world as we know it, that ended poverty in a single image - would it do more if it was uncompressed? No. Quote Link to post Share on other sites More sharing options...
pico Posted October 24, 2011 Share #17 Posted October 24, 2011 I'm really surprised that DNG compression tosses away information. It was based upon TIFF, in fact it's an extension of TIFF which has lossless compression al an LZW option in PS. I should think that Leica would do the same. 1 Quote Link to post Share on other sites More sharing options...
farnz Posted October 24, 2011 Share #18 Posted October 24, 2011 This is not quite how it works. ... Okay, then perhaps we can look at this way: where a number of consecutive pixels are registering identical 16-bit words, for example an area of pure black in a coal mine yields 256 consecutive identical pixels:rolleyes:, then rather than record three separate, identical 16-bit words for each register (RGB) the compression algorithm can identify that they're all the same and in place of 255x3 produce an instruction that says "the next 255x3 words are the same as the first word". This will remove data but not information. Pete. Quote Link to post Share on other sites More sharing options...
pop Posted October 24, 2011 Share #19 Posted October 24, 2011 ...This will remove data but not information. That would be called "lossless compression" because you can restore the original data. This particular method is called "RLE" for "run length encoding". Quote Link to post Share on other sites More sharing options...
dwbell Posted October 24, 2011 Share #20 Posted October 24, 2011 Is RLE not lossless? Quote Link to post Share on other sites More sharing options...
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