M8 == 8bits

This is about the limit of what the M8 can do without getting into PS tricks
light.jpg
 
Richard Marks said:
Well lets see what we can do
Some of the highlights on the right hand side are s bit gone but still detail in the pillars
Shadow detail of the pews a bit better
Windows have appeared in the left side of the image
The catch is always in an accurate comparison and clearly we can only guess if the image would have more highlights with the big gun big bit machines.
Regards
Richard

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View attachment 56270
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Thanks... I guess we don't need to compare to big guns, a simple Canon 400D would do the trick. I can tell you we don't need to guess if higher bit depth would save the highlights. I thought about this a little and it's pretty obvious why Leica needs to cut off the highlights. Even though they have 14 or 16 bits of precision, they use a look-up table of 256 values to cover the image.

This means you can have 65536 (if it's 16 bits) different values for light intensity, but only 256 of those can be used in a single image. This actually works pretty well if the values are close to each other. A regular 8-bit image has 256 linear shades of light (from 0.0 to 1.0, or black to white), but the M8 compression is actually able to fine-tune the selection. This obviously results in better-than-8-bit results as long as the compression code is doing a good job. It's not as good as real 14-bit image, but perceptually it can be fine, especially if minimal post-processing is applied.

It *would* be a perfect solution but you simply can't allow any over-exposed pixels (value over 1.0) as that would decrease the quality of the "visible" light. If you allowed 4x over-bright, you might have to use more than half of your 256 values to cover pixels that appear white unless the exposure is changed (a real 14-bit image could be for example 12:2 fixed point value where you have 12 bits of decimal and couple bits for pixels that are up to 4 times brighter than white).

Your photos are beautiful, no question about that. It's just that with M8 you need to watch those highlights (and at higher ISO you need to watch the shadows, too).
 
xihalife said:
Thanks... I guess we don't need to compare to big guns, a simple Canon 400D would do the trick. I can tell you we don't need to guess if higher bit depth would save the highlights. I thought about this a little and it's pretty obvious why Leica needs to cut off the highlights. Even though they have 14 or 16 bits of precision, they use a look-up table of 256 values to cover the image.

This means you can have 65536 (if it's 16 bits) different values for light intensity, but only 256 of those can be used in a single image. This actually works pretty well if the values are close to each other. A regular 8-bit image has 256 linear shades of light (from 0.0 to 1.0, or black to white), but the M8 compression is actually able to fine-tune the selection. This obviously results in better-than-8-bit results as long as the compression code is doing a good job. It's not as good as real 14-bit image, but perceptually it can be fine, especially if minimal post-processing is applied.

It *would* be a perfect solution but you simply can't allow any over-exposed pixels (value over 1.0) as that would decrease the quality of the "visible" light. If you allowed 4x over-bright, you might have to use more than half of your 256 values to cover pixels that appear white unless the exposure is changed (a real 14-bit image could be for example 12:2 fixed point value where you have 12 bits of decimal and couple bits for pixels that are up to 4 times brighter than white).

Your photos are beautiful, no question about that. It's just that with M8 you need to watch those highlights (and at higher ISO you need to watch the shadows, too).
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At last! Thank God!
You have come up with a technical explanation which seems to satisfy youto some extent. All that i asked of you was to try it for yourself. It would have been quicker!
Glad you like my pictures. Enjoy your M8 which as you point out can only get better.

Richard
 
rsl said:
Very nice, Jaap. In the original, is there still detail in the bright side of the pulpit? It looks a little blown out on my monitor, but the shadow detail is outstanding.
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Yes- I have some detail left in the highlights in RAW, but I would have to layer and dodge and burn to get it on the screen.
 
jaapv said:
Yes- I have some detail left in the highlights in RAW, but I would have to layer and dodge and burn to get it on the screen.
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After looking at the excellent files you uploaded for me I suspected as much. I wish I could have been standing next to you shooting wih the D3 for comparison. I've found that the deep photosites Nikon provided with their 12 megapixel full-frame give me a noticeable improvement in latitude. At least I think it's the photosites. There's probably some new processing going on too.
 
sitemistic said:
A little playing around in ACR and PS3
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Very impressive. I know where to send my probelm files!
You know I did not really imagine my interior shot would lead to all this but I hope we have proved that the M8 files (8 bit or what ever they effectively are) can cut it for high dynamic range. Incidentally my church shot looked pretty much like it originally was. You do not see that much shadow detail with your eyes!

Richard
 
footnoteblog said:
Jaap, you should check out the Fill Light feature in Lightroom. It's pretty blunt, but works much like HDR (but not like the typical HDR shots).
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I don't use LR, don't like it. I use either C1 or ACR, and pp in CS3, ACR has the same features as LR.
 
jaapv said:
I don't use LR, don't like it. I use either C1 or ACR, and pp in CS3, ACR has the same features as LR.
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Hmm. I think Lightroom has a lot more features, but if you don't like don't use it, certainly! 🙂

Anyway, at least try out the Fill Light feature (for shadows).
 
footnoteblog said:
Hmm. I think Lightroom has a lot more features, but if you don't like don't use it, certainly! 🙂

Anyway, at least try out the Fill Light feature (for shadows).
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I think you will find that quite a lot of Leica RF users have chosen the M8 for the amount of control that the camera affords. Possibly not the main stream of post processing electronic wizardry. The idea is to get the shot. Occasionally minor tweeks here and there are necessary, but personally i would much rather spend the time taking photos than pouring over a PC monitor. Eachto their own of course.

Richard
 
footnoteblog said:
Hmm. I think Lightroom has a lot more features, but if you don't like don't use it, certainly! 🙂

Anyway, at least try out the Fill Light feature (for shadows).
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If you think Lightroom has more features than CS3 you need to try CS3. As far as ACR is concerned, it's the same in Lightroom and Cs3.
 
jaapv said:
That is correct, Russel. The only reason, imo, to prefer LR over CS3 is the price.
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LR and CS3 are for different use. I catalog my images in LR and if serious editing is needed I send them to CS3. But generally LR has easy slider controls to almost everything I need. It imports RAW and has excellent automatic settings for JPEG conversion. I could think of taking a set of 50 RAW's and making JPEG's out of them using CS3... (surely if you don't post photos on the web you might not care about it).
 
xihalife said:
LR and CS3 are for different use. I catalog my images in LR and if serious editing is needed I send them to CS3. But generally LR has easy slider controls to almost everything I need. It imports RAW and has excellent automatic settings for JPEG conversion. I could think of taking a set of 50 RAW's and making JPEG's out of them using CS3... (surely if you don't post photos on the web you might not care about it).
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Yes, Lightroom has features that are very useful if you're a pro trying to get hundreds of images from a shoot under control. But for a complete set of post-processing features nothing can beat CS3.
 
Yeah, don't get me wrong, I use Lightroom for light cleanup, color balance (and Fill Light!!!). Lightroom is not the same as ACR, and CS3 cannot be beat. If at all-- the DNGs are so crisp and focused as well as perfectly exposed (pats self on back). 😀

After that, I'll tweak a TIFF in 16-bit ARGB for output in CMYK, if at all necessary.
 
I use Canon DSLR's and a Leica M8. With a Canon, you have to expose further 'to the right' than with the Leica. Meaning that the histogram has to make full use of the highlight area, whereas it's best to keep Leica exposures further away from highlight clipping.

Leica files respond very well to 'lightening' in post processing and have nothing useful in parts that show clipping initially. Canon files are much more likely to have a bit of additional information in the highlights, and somewhat less in the shadows.

Between the Canon 5D and the Leica M8, overall dynamic range, considering a similar noise floor, seems to go in favour of the M8 by about a half stop to a full stop. Both have a lot more dynamic range than any decent slide film ever had, but not as much as colour negative film or B&W developed to a low CI.

In any case, in spite of RAW compression, the M8 definitely produces files that, when opened contain more than 8bits of information. More like 13 or 14 bits, which in actual practice is about the same that I've seen from the DMR, in spite of the '16 bit' PR. Those last few bits are MIA.

The granularity of the M8 files over its dynamic range is so fine that a quick look at the files should be enough to convince anyone that there are a lot more than 8 bits available here.

JPEGs are 8 bits, albeit over a much smaller dynamic range usually, but even over this limited dynamic range the granualarity is much coarser than that of the M8 RAW files.

Henning
 
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