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What the hell is that thing? A maze in light

nivillard

By nivillard
in Leica Q3 / Leica Q2 / Leica Q

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nivillard

nivillard

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Hi,

Sorry, I don't know the vocabulary for that thing, even in my language, but I was shocked to see that pattern in my photo (see image attached), although it is zoomed at 400 %. I wouldn't have seen it if this pattern provoked a moiré-effect on certain values of zoom. Does anyone know what's the cause for this, and if there is a way to correct it please? I was so happy with that photo that I can't accept it is ruined by that pattern.

Nicolas

PS: I should precise that I shot in front of the sun, and that the girl was wearing a coat with contrasting details (a pattern that does not exactly resemble this one, but that looks alike the moiré-effect on a certain value of zoom, and that is striking).

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nivillard

nivillard

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Here you can see the moiré-effect in the hair and just above the shoulder in the bottom left corner.

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jaapv

jaapv

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I see overexposure, I see flare, I see moiré, I see blown highlights, maybe even sensor blooming. It exhibits about any artefact you can think of. You pushed it far beyond the technical capabilities of any sensor - or film, for that matter. If you value the image, you will need to take some time in Photoshop. It might even turn out quite nice.

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nivillard

nivillard

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14 minutes ago, jaapv said:

I see overexposure, I see flare, I see moiré, I see blown highlights, maybe even sensor blooming. It exhibits about any artefact you can think of. You pushed it far beyond the technical capabilities of any sensor - or film, for that matter. If you value the image, you will need to take some time in Photoshop. It might even turn out quite nice.

Overexposure, I can't see how since the whole picture is rather dark. This part is burnt due to the sun being close to the head, blown highlights too btw. Flare, indeed. Moiré, sure, but why? I have other pictures of that kind without any moiré. Can a sensor be tricked by a pattern on a coat because of extreme conditions of light?

EDIT: To be clear, the whole picture is not the second one. It's far bigger. I can't post it because of size limitations (and because there is a baby on it).

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jaapv

jaapv

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1 hour ago, nivillard said:

Overexposure, I can't see how since the whole picture is rather dark. This part is burnt due to the sun being close to the head, blown highlights too btw. Flare, indeed. Moiré, sure, but why? I have other pictures of that kind without any moiré. Can a sensor be tricked by a pattern on a coat because of extreme conditions of light?

EDIT: To be clear, the whole picture is not the second one. It's far bigger. I can't post it because of size limitations (and because there is a baby on it).

Yes, but in digital photography one exposes for the (significant) highlights and lifts the shadows. Just the other way around from negative film.

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adan

adan

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Anyway, to get back to the various textural problems - what I am seeing in blowing up your samples (esp #1) is that you are getting demosaicing errors. These are places your software gets confused in converting the checkerboard of red, green, and blue pixels of a raw file back into a smooth tonality.

It is a form of moire, caused by the computer being unable to correctly track which pixel brightnesses (luminances) go together, and coming up with an "imaginary maze texture." Often then emphasized by a sharpening setting. The original sensor's checkerboard pattern is "leaking through" the computer's interpretation of data, revealing the actual rows and columns of pixels.

The "artifact" or imaginary texture can then itself moire with actual subject textures, which may explain the waves, stripes or bands in the woman's hair (#2).

A couple of links seem to indicate this may be a "feature" of DxO PhotoLab - and that it may in fact really be a feature, allowing user control of how the pixels are interpreted back into a continuous-tone/color "photograph." Which would extract maximum per-pixel sharpness in some pictures, but go insane in other cases.

The summary - try working with some of your PhotoLab's controls, as mentioned in these posts, to adjust how the math recombines and associates neighboring pixels in "developing" your Q2 files.

https://www.dpreview.com/forums/thread/4221154

https://feedback.dxo.com/t/raw-conversion-challenge-moire/8650

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adan

adan

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BTW I would also agree with the previous posts - with digital, expose for the highlights, and process for the shadows.

Especially with Leica's more recent CMOS sensors and cameras - the image below, from the M10, with related 24Mp sensor, as it appeared on, and came out of the camera (left), and with shadow recovery/exposure adjustments via Adobe Camera Raw (right). (Mis)exposed at ISO 3200, corrected to effective ISO 10000.

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nivillard

nivillard

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4 hours ago, adan said:

BTW I would also agree with the previous posts - with digital, expose for the highlights, and process for the shadows.

Especially with Leica's more recent CMOS sensors and cameras - the image below, from the M10, with related 24Mp sensor, as it appeared on, and came out of the camera (left), and with shadow recovery/exposure adjustments via Adobe Camera Raw (right). (Mis)exposed at ISO 3200, corrected to effective ISO 10000.

I won't say I'm an expert in managing exposure but in few pictures, not all, I had some disappointments with exposing for the lights, finding too much noise in the shadows. That's when I have time (for my level) to select exposure. And in my opinion (which is one from an amateur...), in extreme conditions, like backlight with sun, nothing except HDR permits to capture every shades, am I wrong?

Again, in this case, I find the picture already dark, that is to say, almost exposed for the lights. Not really because I focused on the baby.

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nivillard

nivillard

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6 hours ago, adan said:

Anyway, to get back to the various textural problems - what I am seeing in blowing up your samples (esp #1) is that you are getting demosaicing errors. These are places your software gets confused in converting the checkerboard of red, green, and blue pixels of a raw file back into a smooth tonality.

It is a form of moire, caused by the computer being unable to correctly track which pixel brightnesses (luminances) go together, and coming up with an "imaginary maze texture." Often then emphasized by a sharpening setting. The original sensor's checkerboard pattern is "leaking through" the computer's interpretation of data, revealing the actual rows and columns of pixels.

The "artifact" or imaginary texture can then itself moire with actual subject textures, which may explain the waves, stripes or bands in the woman's hair (#2).

A couple of links seem to indicate this may be a "feature" of DxO PhotoLab - and that it may in fact really be a feature, allowing user control of how the pixels are interpreted back into a continuous-tone/color "photograph." Which would extract maximum per-pixel sharpness in some pictures, but go insane in other cases.

The summary - try working with some of your PhotoLab's controls, as mentioned in these posts, to adjust how the math recombines and associates neighboring pixels in "developing" your Q2 files.

https://www.dpreview.com/forums/thread/4221154

https://feedback.dxo.com/t/raw-conversion-challenge-moire/8650

Thank you very much, I will look at that!

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4peterse

4peterse

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vor 1 Stunde schrieb nivillard:

I won't say I'm an expert in managing exposure but in few pictures, not all, I had some disappointments with exposing for the lights, finding too much noise in the shadows. That's when I have time (for my level) to select exposure. And in my opinion (which is one from an amateur...), in extreme conditions, like backlight with sun, nothing except HDR permits to capture every shades, am I wrong?

Again, in this case, I find the picture already dark, that is to say, almost exposed for the lights. Not really because I focused on the baby.

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I think it always depends on the mood you want to create in your photos. For example, with strong backlight, I wouldn't mind if shadows are dark. Your photo is quite nice without HDR. You can lift the shadows a bit, to show some structures (which I guess you did), and maybe you should have paid attention that the lens flare isn't at the kid's shoulder… but apart from that, good photos don't need to be neutral-grey 😉 

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nivillard

nivillard

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Wow. Frankly I'm stunned... I knew DxO Prime was crazy with noise correction but I tried it with "Labyrinth" at 100... There is almost no more maze in the image, apart from residual presence here and there. You can only see it at 400 % zoom. It means that I can no longer see any moiré effect in that picture (the tool "moiré" in DxO was useless however... but maybe it is not designed to deal with that kind of moiré). I'll show you some results tonight. It's breathtaking. I have to check I've lost nothing in that process, but the worst case scenario is I just have to copy/paste the parts affected (and treated with Prime) on my first picture in Photoshop and alike.

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