1796 - Compared To What

Some days ago Juha posted his findings about the new "High ISO Noise Reduction" setting, introduced with version 2.0 of the Panasonic DMC-LX5's firmware, that was released on September 13. Juha compared two images at ISO 1600, one developed from RAW using Aperture, and the other a JPEG from the camera, with "HIGH ISO NR" set to "on". The image was a "twigscape" with slightly out-of-focus background. Well, I thought I try it myself, but I use my own RAW workflow, trying my best to wrestle the most out of the RAW files, adapting the level of noise reduction to the particular image and trying to sharpen in a way to retain as much detail as possible.

The first comparison is with an image pretty ideal for noise reduction. There are plenty of hard contrasts, and in between we see lots of artificial, uniform areas. ISO is 1600 and you see two exposures: At the left is a JPEG out of the camera with “HIGH ISO NR” set to “off”, in the middle a second JPEG with “HIGH ISO NR” set to “on”, and on the right you see the second image developed from RAW.

The RAW file was converted using the Adobe DNG Converter, then developed in Adobe Camera RAW 4.6. In ACR I’ve completely turned off noise reduction, color as well as luminance. Then, in Photoshop CS3 I have used Topaz DeNoise 5 with a “RAW strong” preset, duplicated the layer, set it to “Luminosity” mode and sharpened that with “Unsharp Mask” (radius 0.3, strength 500, threshold 0). Basically that’s it and the result is pretty obvious.

There is a slight improvement from “HIGH ISO NR = off” to “HIGH ISO NR = on”, but the difference between that and the version from RAW is striking.

OK, that was easy, now let’s look at something notoriously hard, let’s look at foliage. Well, grass or fur would have been even better, but this detail from my living room window in Vienna, seen though the telephoto end of the LX5’s zoom range, is representative enough of a typical “landscape” situation. It was a gloomy, cloudy day (and cold!), so there are contrasts, but much less accentuated, there is not much differentiation in terms of color, and there is a lot of fine detail.

To the left is the JPEG with “HIGH ISO NR” set to “on”. This is a situation that is much harder for noise reduction algorithms - and it shows. On the RAW side I have used much less aggressive noise reduction, and the sharpening layer was tempered with an edge mask. You may have noticed in the last example that the colors from RAW were more vivid than from the JPEG, and so it was here, but while that looked attractive on the artificial surfaces, it looked gaudy and wrong here. Thus I have desaturated the yellows, mixed a tiny amount of magenta into the yellows and finally darkened the image slightly. In the end I got something sufficiently similar in color to the JPEG from the camera, that the eye can fully concentrate on noise and detail.

I think the result is again a win for RAW, although with this material it is less dramatic. There is more detail, yes, but there is also more noise. I’ve tried a few things, different settings of Topaz DeNoise, different sharpening, fiddled with the edge mask, but whatever I did, when I got less noise, the shadows became invariably mushy, just like in the JPEG from the camera. I don’t say it’s the optimum, but I think it’s as far as I would go for a normal Image of the Day. Every tiny bit of additional progress would have to be bought with obscene amounts of time.

So, here we are. I see an improvement possible by setting “HIGH ISO NR” to “on”, but it is not comparable to what you can reach by going through RAW and using a high-quality noise reduction program that you can parametrize according to the image’s needs.

We can also see that ISO 1600 is possible on this camera, albeit only for certain subjects. Artificial surfaces with hard edges and not much texture work best, for landscapes though I would not go higher than ISO 400.

The Song of the Day is “Compared To What” from Roberta Flack’s 1969 debut album “First Take”. Hear it on YouTube.

There are 2 comments

Juha Haataja   (2011-09-20)

Thanks, convincing! One subject which might be worth trying out is a landscape with graduated blue sky - typically noise gets rather intrusive there, at least I have found it so.

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andreas   (2011-09-20)

I normally solve this by duplicating the basic layer that I've got from the RAW converter. Then I do different levels of noise reduction - strong for the sky, weak for the landscape - and blend them with a mask. In Photoshop you can use "Select color range" on the sky, and that normally gives you a fine sky mask with a few clicks. If there are other blue parts in the image, you can always paint in the mask. The blue of the sky tends to get lighter near the horizon, thus the opacity of the layer with strong NR will get weaker, but that's OK as well, because noise is mostly a problem in dark areas, at least as long as you have exposed properly. For sharpening I often use the same kind of mask. Sharpening white clouds may be OK, sharpening the blue backdrop is stupid, thus I use a mask. All these adjustments are local. No camera can do that for you, and that's the reason why I always use Photoshop.

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