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In praise of M8 sensor...


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Well, I read always with interest the threads about 8 bit compression on M8,and its various implications on image quality... and I also remember to have read many times how good is M8 sensor in shadow details...

Happened two days ago I had an impressive confirmation of how good are M8 sensor capabilities (to be honest, I haven't experience with any other digital camera, apart my phone... :)). During a macro take, in manual mode, i simply set GROSSLY WRONG the exposure... don't remember why... anyway this was the original DNG out of the camera... Ok, a frame lost:

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But what astonished me is what I could achieve playing a mix of exposure adjustement and "Fill Light" function in Lightroom (without any other action to reduce noise, or adding blur or so) :

Maybe it's normal for digital... but I was really surpised on how much M8 can "forgive"... woah, it's a great camera.

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It will look even better if you run Neat Image or Noise Ninja on that image. Here is Neat Image quick and dirty. It could be improved with a bit more care and tweaking.

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Edited by jplomley
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Luigi, Jeff has shown you one way to improve your saved image. I would suggest that you try processing it in C1 Ver4.8, if you have a copy of it. I believe you will see futher evidence of the "forgiveability" of the M8 sensor!

 

On occasions when I switch to 'manual' on the M8, I sometimes forget to adjust when shooting next in another environment and have had, like you, a seriously underexposed image. Wnen properly processed in C1, and maybe others, magic does happen. Despite its shortcomings, the M8 and its sensor are fantastic tools worthy of skilled hands.

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Thanks for the advices: I never tested Noise Ninja or Neat Image... are they easy to find and install ? Jeff, your processing of my "dirty" image is really impressive: I think they worth a try...

Erl, I had C1 still installed, but didn't upgrade after the version that came with my M8 (April 07), for I bought LR and like it more in term of user interface... I know that C1, for many, does have something more... but dealing with two RAW developer, for me, would be too much... :(

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Luigi,

 

I guess that this picture was taken at low ISO. At ISO 160 the dynamic range is 11,5 stops, when shooting raw, wich is very, very good, enabling you to recover information from very dark areas.

 

- The outcome out of my last series of postings, was that compression does mostly affect the middle bright luminance values, but hardly the very dark areas as in your picture.

So compression does not have a negative impact here.

- The second point you praise is the sensor. In that respect you cannot say that noise in the picture is just sensor noise., there is also a A/D converter playing an important role.

As I have tried to show here , http://www.l-camera-forum.com/leica-forum/898557-post79.html, that the M8 has a superior A/D converter. adding much less noise then the high end cameras from Canon.

On the other hand, sensor noise is worse in the M8 as it is in other high end cameras, but this only becomes evident at higher ISO values.

At low ISO values the noise from the A/D converter is the more dominant one.

So if your picture is indeed taken with a low ISO value, the noise you see is not even sensor noise but mostly A/D noise.

 

Hans

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Dear HAns

Very good explanation. It is surprising more because M8 does with only 8 bits. I believe they use a logarithmic compression (takes 16 bits of sensor data and turns into non linear 8 bit code) that leave most of the detail in the dark areas (low values, shadows) and compresses the highlights where most people would not see detail anyway.

Very clever.

regards

Victor

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Dear HAns

Very good explanation. It is surprising more because M8 does with only 8 bits. I believe they use a logarithmic compression (takes 16 bits of sensor data and turns into non linear 8 bit code) that leave most of the detail in the dark areas (low values, shadows) and compresses the highlights where most people would not see detail anyway.

Very clever.

regards

Victor

 

Victor--yes--IIRC, the M8 takes 14bpp data and compresses that to an 8bit non-linear representation--which is then uncompressed in RAW space, with some loss :) But just so readers are clear: the M8 does not record an 8-bit picture (like a JPEG), which people get messed up on all the time.

 

The latitude in the shadows on the M8 at lower ISOs (right up to 640) is still quite astounding. Only the newest generation of dSLRs, IMO, have the same amount of room to play.

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It will look even better if you run Neat Image or Noise Ninja on that image. Here is Neat Image quick and dirty. It could be improved with a bit more care and tweaking.

 

Sorry, but this looks really bad IMO.

The original has much better texture.

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Sorry, but this looks really bad IMO.

The original has much better texture.

Agree completely. The Neat Image treatment seems to strip all the life from the flower. It is OK if you want the Nikon/Olympus look & I guess the Noise removal may be useful for 2500 ISO shots.
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Agree completely. The Neat Image treatment seems to strip all the life from the flower. It is OK if you want the Nikon/Olympus look & I guess the Noise removal may be useful for 2500 ISO shots.

 

Each has its own value. The NR image accents the 3-d, making the background quote OOF and the edge sharpening makes it stand out.

 

It also takes out detail though. The human brain is very good at extracting signal from noise (think conversation in a restaurant) but there is also a concept called 'dithering'. It works in audio and video alike. When the noise is random (as these images are) the eye accepts the dithering and actual 'perceives quite a bit of detail. It is why some actually like (and ADD!) grain to images.

 

chaqu'un a son gout

 

Victor

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Hey, I said it was quick and dirty and not optimized. Give me a break already!
Jeff, sorry no offense was intended. In fact I am very impressed with the quality of the image after removal of the noise so for some applications (like ISO 2500, which from a noise point of view is similar to the vastly underexposed picture in the OP) it is very useful. But in this case the noise in the original image is fine with me and more texture of the flower is visible.

 

Have you tried 2500 ISO treatment? I would be interested to see that.

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Actually, the original image is kinda interesting. What happens when you pull the highlights out just a little bit more?

 

(At work so I can't experiment -- yet...)

 

I tried (always LR)... but going on with pulling highlights starts to show artifacts in the noisy areas...

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I tried (always LR)... but going on with pulling highlights starts to show artifacts in the noisy areas...

 

I was thinking something which still kept it very dark.

 

I did this in PS CS4. In levels I pulled the right side of each channel down from 255 to 200. Then I adjusted the highlights in color balance more to red, magenta, and yellow. Then I let Noise Ninja sample the image and went with its output.

 

When I saw your first image, I saw a night flower.

 

Totally irrational, I know, but fun with pictures. :)

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I tried (always LR)... but going on with pulling highlights starts to show artifacts in the noisy areas...

 

Can't stop playing...

 

Again in PS CS4. This time I went to Levels and did Auto. Next, I went to Curves and set the white point to that little highlight on the tip of the petal on the right. The black point was set to an area close to the bottom towards the right. I did another try with Noise Ninja, and reduced the settings to 7, 8, and 9 (NN users should know where that is).

 

I was surprised at how nicely the background stayed dark.

 

And there is still lots of room to play in.

 

But to your original point...Yes, there seems to be some headroom to play with.

 

Please feel free to share any other "failures". :D

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Sorry, ljclark, I hadn't understood well your post and made another kind of developing.... really, as you say, keeping vey dark the background can give a special feel to my pic, your last PP is very fine. Anyway, is the first time that a pic of mine arises such interest for processing... it means SOMETHING that it's a "wrong" one ... :o but is very satisfactory to see people working on an image taken by me !!!

(I forgot to mention that, clearly, I realized at once on the LCD the exposure error... and shot another, correct... )

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