Leica TL2 greenish tint

[nthpeter]

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On 2/5/2022 at 2:05 AM, jaapv said:

In postprocessing I rarely have to pull up the shadows by more than 40-50%, and that only in high- contrast situations.

My expectation was that I can do that without going slightly towards green. That is what this thread is about, Hello.

On 2/5/2022 at 2:05 AM, jaapv said:

I can simulate this

Yeah, I can simulate it too, see my attached picture. You jumped to the conclusion that all my pictures are underexposed, while I said several times that underexposed parts happen with correctly exposed pictures too, where the dynamic range is too high. Which happens to you too, according to what you just said, but let me quote it again before you forget:

On 2/5/2022 at 2:05 AM, jaapv said:

I rarely have to pull up the shadows by more than 40-50%, and that only in high- contrast situations

So you need to pull up shadows with certain pictures. My problem is, to summarise, and I hope it's understandable this time, that pulling up shadows, even if not significantly, result in non-uniform discolouration. What bothers me is that I know the shadow is going towards green, I know the camera is built like that, so if I pull shadows up 20% it might not be obvious at first sight, but if I zoom in or look at the picture on a big screen I can spot the disproportionate green.

The process I described above (pulling up shadows and exposure to the max, fixing the green issue with shadow tint, then pushing back the shadows down to the desirable level) is to relax my mind that there are no non-obvious green spots, no discolouration noticed only 10 years from now when I look at old pictures, etc., because shadows at the maximum possible forced exposure are tint-free, so bringing them back to a lower value will definitely be green tint free.

Sony cameras are much cheaper than the Leica with the same sensor and similar tech, and we can see that this problem can be fixed purely with software (see M240's case), so I (naively) expected Leica to provide that and I can do whatever I want with the picture because it will be uniform.

And even if in theory I underexpose some of my pictures, the same way like the example attached to the blog post with the M240 (https://blog.kasson.com/the-last-word/mastering-leica-m240-green-shadows/), other cameras can solve that issue and bring back non-green shadows. The blog owner started that thread because his M240 can't do something his other cameras could. I will not accept you saying that other (even cheaper cameras) can handle shadows correctly, but my TL2 can't, so I always have to expose it correctly. No, it's a defect that is being solved by other brands (maybe even other Leica cameras, well not the M240 obviously), especially at this price point.

[jaapv]

The Kasson blog is about the M240 sensor and he provides the explanation. You can find the same problem in other brand forums. CCD sensors are even worse BTW. You can correct the shadows with a blending layer in LAB and split the sliders. It will be mitigated to a large extent if you expose for the shadows. 

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[nthpeter]

23 hours ago, jaapv said:

The Kasson blog is about the M240 sensor and he provides the explanation. You can find the same problem in other brand forums. CCD sensors are even worse BTW. You can correct the shadows with a blending layer in LAB and split the sliders. It will be mitigated to a large extent if you expose for the shadows. 

Yeah, I know what the blog is about and what the explanation is  

The only lesson from there is that even with a more expensive camera there are (more noticeable) problems and Leica didn't seem to address it in any way, even though a plugin was enough to fix the issue, so I can't expect anything official for TL2.

And the fact that your CL behaves the same way means that my TL2 is not particularly worse than it should (I assume), it behaves according to the sensor and SW in camera.

I searched for a tutorial about LAB and it looks like a promising mitigation going forward. Thanks for the tip!

[jaapv]

So Leica should introduce a Bayer patter with fewer green pixels? Or compromise colour rendering at proper exposure? Take it from me, if there is one thing in digital photography that Leica is leading in, it is colour technology.  But they also tend to do less pre-cooking than other brands, leaving more options open for the user. Yes, LAB is  the most powerful tool for colour processing, but mastering it will give you a headache from time to time   (Well worth it, though. 

[nthpeter]

On 2/12/2022 at 2:15 AM, jaapv said:

So Leica should introduce a Bayer patter with fewer green pixels? Or compromise colour rendering at proper exposure? Take it from me, if there is one thing in digital photography that Leica is leading in, it is colour technology.  But they also tend to do less pre-cooking than other brands, leaving more options open for the user. Yes, LAB is  the most powerful tool for colour processing, but mastering it will give you a headache from time to time   (Well worth it, though. 

You don't seem to understand the m240's problem or my problem in fact. The problem is that channels with low values are clipped straight, and that leads to disproportionate green shadows (since the green channels have inherently higher values, so a clipping should be made separately per channel, not with a uniform value for all channels). This is a bad choice by Leica that can be mitigated by a simple LR profile for the m240 (again, a $5000 camera). Mitigated, but not fixed, as Leica removes information that can't be recovered.

In fact I did ISO tests and the disproportionate clipping in the TL2 goes higher and higher until ISO6400, where it actually reverts to no clip, resulting in higher but uniform color noise. Up until ISO5000 the green discolouration is getting worse and worse, when it magically stops (clear sign of software manipulation).

I'm working now on reading my RAW files with python to clip the green channel at a higher value than the rest, to at least have a uniform shadow color when increasing exposure, not the greenish tint. This will hopefully be ISO-independent (unlike the LR profile for the m240). I accumulated a large number of DNG files ready to be deleted, but I need to process them with my program to get rid of the discolouration first, then use LR to apply the usual fixes (changing exposure, etc.), and then produce the JPGs to keep.

[jaapv]

I have used an M240 for five years and about 50.000 shots and I certainly don’t understand your problem as I never had an issue with it. Nor do I understand why it appears in a TL2 thread