Weird color blotches


I noticed some weird color blotches in my images from a Nikon Z6, that are not apparent, when I look at the original Nikon jpgs.

The following images are crops from the exported Photolab image on the left and the Nikon jpg on the right:

These are the default Standard settings:

As the Photolab standard setting is hopelessly oversharpened, I also sharpened the Nikon jpg for a better comparison. The grey walls still remain gray in the Nikon version, while the Photolab version has all kind of weird colors:

I tried with HQ noise reduction on and off, with moiré correction on and off, nothing helps to make the photolab image appear normal. Is there any solution to this? I am using Photolab 5.10.

I also compared with DeepPrime (left) vs the sharpened Nikon jpg. With DeepPrime, the problem does not exist, it looks very similar to the Nikon jpg (maybe even a touch better). However, I’d not like to use DeepPrime on every image (especially since no noise reduction has been used at all on the Nikon file).

This is a common artifact, not exclusive to PhotoLab. It’s good that you tried moire removal to see if that helps. Have you tried adjusting other noise reduction parameters? (It’s probably low-frequency chroma noise you’re seeing.) Or chromatic aberration removal?

I wouldn’t call any sharpening in PhotoLab hopeless. It’s very easy to reduce the amount of sharpening applied. :smile:

Thanks for your response, I just wanted to try that and I realized I only verified whether the moiré removal made any difference in the Nikon software (where it did not have any effect). The moiré removal has not been active in Photolab (the default). If I activate it to 100% (the magic wand sets it to 100%), it works and is removing the artifacts.

Photolab with moiré removal left, sharpened Nikon jpg right:

OK, almost hopeless, I have to go to the limit and set the sharpness to -3 to -2 for a comparable sharpness. :wink:

I had a look at several of the pictures of the Z6 with the 24-70 f/4 S lens, and there are quite many pictures with moiré. I guess that this lens is quite sharp and Photolab is not setup to correct for it by default. The standard preset has moiré removal deactivated. If I use the magic wand, it always sets the correction to 100% in all the pictures that I have tried, which is quite a high value as I noticed. A setting of 25% seems much better, as the 100% setting is destroying quite a bit of detail!

For example, here, I show 3 settings, from left to right 0%, 25% and 100% moiré reduction. With 0%, there are some color blotches on the asphalt. With 25%, these disappear. At 100%, the details of the red pants completely vanish!

In this crop from the same image, (again 0%, 25% and 100%), there is no moiré visible even at 0%. I just wanted to show how 100% correction completely eliminates the color from the faces and the yellow jacket!

So I am a bit puzzled. With the jpgs, that problem does not exist. Do the pictures require a default moiré correction of 25%?

JPEG files from your camera are already demosaiced and processed for artifacts. RAW files aren’t. Having to remove moire is normal but not necessary for every image, so you’ll have to decide what’s best. If 25% does no harm, why not make it your default setting?

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I recall asking DxO Support (some years ago) if there might be any downside to having Moire activated by default - and they advised against that … But, perhaps that was because they assumed my default would be applied by the “Magic Wand” (?)

RAW files are not corrected, if you deactivate all settings. But with the standard preset, there is already correction for noise, hot pixels, lateral and axial aberrations, vignette, sharpening, lens distortion, etc. all activated by default and at settings specific to this camera lens combination. So I would expect that the same would hold true for moiré, for granted, it will not always work in all images, but it should be a setting that works in the majority of images. With other cameras, I never had problems, so I would imagine that this is specific to the insufficient preset/lens profile.

The moiré correction can be quite harmful, if applied too strong. So Maybe 25% is a good default setting, maybe it is too strong in some cases. I will have to watch this with more images.

FWIW, I don’t think DxO ever promised that its standard preset was a panacea or was even entirely tuned to a particular camera-lens combo. To some extent, yes - but not entirely. As with moire correction, too much or not enough noise reduction is also bad. The standard preset of 40 (which isn’t ISO-dependent) is way too much for most of my images, while my own preset of 15 generally does no harm but is occasionally not enough. Each of us has to find what’s right for our own photography and tastes.

Not true. Some corrections are applied even if all adjustments are deactivated. For example, white balance and color rendering.

That is not my experience, as moiré is much more dependent on the image itself: fine detail, noise patterns, demosaicing, and other variables all contribute independently of the make and model of camera and lens used. Maybe someday a complex AI algorithm to deal with such aberrations will exist. Or maybe it will become possible to apply moire correction locally to an image. But for now it’s a simple adjustment like chromatic aberration correction and noise reduction: the same default value for every camera and lens.