one more time: 8bit DNG vs. jpeg?

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rami G

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Since I have just decided to get a silver M8, rather than a black one (actually, I am just obeying my girlfriend. I like the black better and I have 5 black leica lenses and only 2 silver...) I realized that I can get it sooner than I thought. I still have, though, just one more last hesitation. I am not a techno guy. I understood the camera is only 8 bit color depth while my 5D and my R-D1 are 12 and the DMR is 16bit. Does it mean that I am basically buying a Leica Jpeg camera? What is the difference between a 8bit raw (DNG) and a Jpeg? I guess the white ballance options are still better with the DNG file, but besides that- did I get what's going on here or am I totally missing it? I hope nobody minds the question, I know the issue was discussed thoroughly, but when it was discussed technically I understood very little of it.
 
Only 8 bit? Actually my R-D1s is 16 bit when I output from it's RAW converter into a TIFF format. Is this true about the M8?
 
Sailor Ted said:
Only 8 bit? Actually my R-D1s is 16 bit when I output from it's RAW converter into a TIFF format. Is this true about the M8?
Click to expand...

Yes its true, but it's not as bad as it seems on the face of it. It has to do with creating an efficient gamma based look up table that puts most of the gradations where you need them, in the shadows, rather than wasting then in the highlights. Whether this all works in practice remains to be seem. The up side is the camera works about twice as fast. There may be no practical down sides but this is all very contraversal.

Rex
 
Jeez Rex can Leica change this later in firmware if they wish or if it turns out that it is a big deal? Also does this seem to have any down side in terms of color? What are the MF players doing in this respect? (I guess I'll find out soon enough, but jeez).

Also and somewhat off topic but I've been reading some interesting posts on a different forum regarding Leica's use of a "thinner" IR filter in front of the digital sensor. According to one guy who on the surface really sounds like he knows what he's talking about, it's not that thin comparatively speaking (and a few other things I’ll not share just yet). Now I'll bet you know what I'm talking about, and I’ll bet your also aware of other points not being discussed here on RFf so what do you say boy, are you going to cough that up or what?

Perhaps it's time for a new thread and a little more "canon" foughter for the M8 haters? On second thought : )
 
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The current LeicaFotografieInternational deals with the colour depth of the M8.

The DMR and some MF-backs have 14bit and convert this data into a 16bit file. The DMR doesn't reduce the file size -> 10Mpixel @ 16bit = 20MB file size. Some MF-backs compressing their files just like .zip or .rar . They've tried this with the M8 but the camera became too slow (not so important with MF-backs). So they've decided to save the colour information non-linear. Brighter parts are saved with lower "colour depth" while darker parts (shadows...) are saved with higher colour depth (because the eye is more sensitive in these areas).
But ordinary programms cannot handle this specific type of TIFF-file (they're always linear), when you want to get the full information in your TIFFs you need to convert them with 16bit - not 8bit! The differences are extremly small - but not like RD-1 or Canon - where 8bit should be sufficient.

The JPG-quality of the M8 isn't too great (actually it's much worse than Canon). ALWAYS shoot DNG! These files have quality!
 
georgl said:
The current LeicaFotografieInternational deals with the colour depth of the M8.

The DMR and some MF-backs have 14bit and convert this data into a 16bit file. The DMR doesn't reduce the file size -> 10Mpixel @ 16bit = 20MB file size. Some MF-backs compressing their files just like .zip or .rar . They've tried this with the M8 but the camera became too slow (not so important with MF-backs). So they've decided to save the colour information non-linear. Brighter parts are saved with lower "colour depth" while darker parts (shadows...) are saved with higher colour depth (because the eye is more sensitive in these areas).
But ordinary programms cannot handle this specific type of TIFF-file (they're always linear), when you want to get the full information in your TIFFs you need to convert them with 16bit - not 8bit! The differences are extremly small - but not like RD-1 or Canon - where 8bit should be sufficient.

The JPG-quality of the M8 isn't too great (actually it's much worse than Canon). ALWAYS shoot DNG! These files have quality!
Click to expand...

Thanks for the info and the tip on Leica Fotografie International and I concur always shoot in RAW or what ever your highest resolution setting may be (DNG on the M8). Regarding the R-D1 and 8-bit vs. 16-bit there is a pretty big difference in color depth to my eye between the two save as options with this camera. I'll keep both eyes open when viewing my M8 images especially in the highlights as this seems a somewhat odd solution- my R-D1 does not have any speed issues when shooting RAW so why would Leica need this peculiar work around I wonder? Is it just for JPEG or a carry over from JPEG speed requirements into DNG where it may not be needed? Curiouser and curiouser. This camera is either brilliant, or a farce.
 
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Sailor Ted said:
Curiouser and curiouser. This camera is either brilliant, or a farce.
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There are some highly technical discussions, way over my head, on LUF, if you are interested. Anyway, I go with the results and as I'm sure you'll agree, those suggest that it was indeed brilliant and the whole numbers game spun around this alleged "issue" is indeed a farce... Btw, it is advisable to set the capture to DNG+jpg basic in the user profile one uses for black and white photography to get the LCD to show the B&W picture.
 
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Has this been confirmed? When my memory serves me the outstanding results from the DMR where believed to be due to the 14, if not 16, bit A/D converter instead of the 12 bit converters typical dSLRs use.

When I sold proof printers, i.E. Tektronix Phasers for colour and Lasermaster for B/W, I learned that a scanner needs at least 14 bit A/D conversion for a printable result and that the scanners dMax is directly conected to the bit depth of the A/D converter and, of cause, the ccd :)
 
Please note that most digitial DSLR use 12bit DAC, so even if you shoot RAW and convert to 16 bits TIFF, there is only 12bits of actual data.
 
Socke said:
Has this been confirmed? When my memory serves me the outstanding results from the DMR where believed to be due to the 14, if not 16, bit A/D converter instead of the 12 bit converters typical dSLRs use.

When I sold proof printers, i.E. Tektronix Phasers for colour and Lasermaster for B/W, I learned that a scanner needs at least 14 bit A/D conversion for a printable result and that the scanners dMax is directly conected to the bit depth of the A/D converter and, of cause, the ccd :)
Click to expand...


this is basically what I understand, and that raises my "last minute" hesitation. Probably the most interesting question is whether the DMR has that advantage over the M8. The answer "8bit is fine for any practical purpose" sounds like "jpeg is fine for any practical purpose" to my "uneducated" ears. If the DMR does get significantly more information in the files than the M8 I would rather change my Canon system to the R system and keep using my R-D1 as my D- rangefinder.

Also- theoreticaly,- is that a firmware upgradable issue?
 
I've compared M8 and DMR-files and they were quite similar regarding DR and other quality aspects.
LFI said that they've compared the "DMR-way" (saving the data directly into a 16bit-DNG-file) to the non-linear "8bit-way" - and there was no visible difference at all - the human eye itself is always a very limiting factor ;-)
The whole sensor-technology and A/D-conversion (14bit) is still 100% MF-back technology and the M8-files also look like this.
From what I've seen, it's true. I've shot thousands of pictures with the M8 so far and the image quality was/is first class!
Try it yourself, I guarentee you, you won't be disappointed!

The DMR/R-System was too heavy for me - I've sold all my Hasselblad and my R-stuff except for one R8 and the fabulous Apo-Elmart 180 and bought the M8 in addition to the "classic way" with the MP/M3 - I didn't regret it!
 
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Since we almost always convert to 8-bit when outputting (either to web or print), 8-bit is clearly enough *if* the bits are in the right places of the brightness scale.

To achieve this without the lookup table would take at least 12 bit depth, but with the lookup table, it's like taking the best of the DNG (the shadows) and combining it with the range where 8-bit provides more than enough info: the highlights.

I don't have the M8, but would like to ask users - I'm happy that a well exposed DNG has the quality from a 12 or 14 bit linear RAW - but what happens when you want to pull back overexposed highlights? You'd think that there would be less range there from the effective compression. Any comparisons out there?
 
The M8's Kodak sensor actually has intrinsic dynamic range slightly better than the DMR. While it seems that you would need at least a 14 bit encoder to store 14 bits of information the trick is to throw out the useless over detailed bits in the highlights, and realocate the tonal information in the most efficient manner possible, via a lookup table that optamises the gamma curve.

If its any consolation, NASA has been sending data back to earth using a similar algorythm. This is really old hat to the rocket scientist. Us camera dudes are a little behind the times when it comes to efficient codes.

That being said "does it work"? Theory is great but the proof is in the pudding. So far there are no complaints but its still early. I'm sure there will be dozens of people pixel peeping the difference in files. Wheeh!! fun!! even more contraversy!!

Rex
 
thanks all. I believe I am confident enough as many of you guys seem to know much more than I do and be confident about it. I am planning to get the silver M8 as soon as it is available again. (heared it will be around mid Jan).


Peter G1G2 said:
Rami and Sailor Ted,

please take a look at this thread:

http://www.leica-camera-user.com/digital-forum/11560-leica-news-lfi-1-2007-a.html?highlight=bit+16

I'm not a technical guy either, but word is Leica came up with fancy math that makes the camera faster and the files smaller. (not visible to the eye, by analysis, or in prints.)

Cheers,

Peter
Click to expand...
 
Ok, so the old Leica Magic still works.

2^14 = 16384

2^12 = 4096

2^8 = 256

256 + Leica Magic > 4096


And Velvia 50 exposed at EI1600 equals 25MPixel :)


Every f-stop is half the light, i.E.

1. 256
2. 128
3. 64
4. 32
5. 16
6. 8
7. 4
8. 2
9. 1


vs.

1. 4096
2. 2048
3. 1024
5. 512
6. 256
7. 128
8. 64
9. 32
10. 16
11. 8
12. 4
13. 2
14. 1
 
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rami G said:
thanks all. I believe I am confident enough as many of you guys seem to know much more than I do and be confident about it. I am planning to get the silver M8 as soon as it is available again. (heared it will be around mid Jan).
Click to expand...

rami G,
I just got mine tonight- I'm excited about the potential image quality especially in light of some of the pictures that are starting to surface. Less so about the M8's ergonomics and the sound of it's shutter : (

Anyway I've got a trip planned to Vegas in ten days so I'll get some great shots (perhaps) and perhaps this camera will live up to what many of us hope for it- time and the city lights of Vegas will tell; not to mention a picture I've got in my mind's eye involving a craps table, a Noctilux, and "Come on. Momma needs a new pair of shoes!"

Ted
 
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Sailor Ted said:
the city lights of Vegas will tell; not to mention a picture I've got in my mind's eye involving a craps table, a Noctilux, and "Come on. Momma needs a new pair of shoes."
Click to expand...

Unless you are planning to share your new M8 with one of the friendly security guards at your favorite casino, you may want to consider the fact that photography is typically prohibited inside casinos in Las Vegas ;)

Cheers,
Mike
 
mbisc said:
Unless you are planning to share your new M8 with one of the friendly security guards at your favorite casino, you may want to consider the fact that photography is typically prohibited inside casinos in Las Vegas ;)

Cheers,
Mike
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Technical, yes. But since the advent of the camera phone, its been enforced rather unevenly. In larger "theme" casinos, where the line between the gambling and the theme is rather blurry you can get away with a lot. And by the way, I was a lot more successful with the RD1 than with a big honking DSLR.

Ted, go for it. Las Vegas is a terrific place to take pictures especially with a rangefinder. If you get busted, the security has always been pretty nice to me.

Rex
 
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