Noise Reduction in C1 6

Noise Reduction in the Age of Affordable Ultra High ISO Shooting

Both LightRoom and Capture One have come a long way in the last several years when it comes to processing very high ISO raw files. With the release of Capture One 6 comes further improvements in color noise reduction. To test this we reprocessed a raw file captured in a situation we feel is typical for a high-ISO photoshoot. This image was part of a photoshoot with a minimal crew of 4, hand held in a bar with a Canon 5d Mark 2 at ISO6400 with a 50mm f/1.2 lens wide-open using an off camera 580 EX flash synced with a Pocket Wizard TT1/TT5. This raw file has a lot of noise, but with the proper processing it can be presented with aesthetically pleasing grain and otherwise good image quality.

Poor Defaults; Great Flexibility

When first opened in Capture One the default noise reduction settings leave much to be desired. Especially for first time users of Capture One this is very disappointing and may lead to false conclusions about what is possible with Capture One for these files. The above screen grab (and below downloadable 100% files) show what is possible in Capture One with a minimum of adjustments. These adjustments can be saved as a style so that they do not need to be reapplied manually in the future, and with Capture One 6’s ‘Import With Style’ feature it can be applied from the moment the raw file is viewed for the first time in Capture One.

Comparing to LightRoom

Raw processors do not exisit in a vacuum unto themselves so we compared In addition to noise reduction this example compares the highlight recovery especially as regards skin tones, color performance in mixed lighting, tonal transitions, and lens correction (purple fringing and chromatic aberration removal) of both Capture One 6 and Light Room 3.

Download the raw yourself and open it in both Capture One 6 and Lightroom 3 and do your own analysis, or if you don’t own or have trials of each program download the 100% comparison JPG.

Tools Used

White Balance

This was one of the hardest decisions in the comparison. White balance numbers (e.g. kelvin/tint) are seemingly ‘universal constants’ but in actuality are not directly comparable between programs. In addition LightRoom exhibited a color shift in bright skin tones when using the highlight recovery tool, making it difficult impossible to set the white balance correctly for both highlight and shadow skin tones. In the end we decided on 4000k/0-tint for both programs. However, we strongly encourage anyone doing further investigation to experiment with white balance in both programs.

Note: One of the reasons white balance is so critical in an article on noise reduction is that this scene was shot at high ISO in very warm lighting. When changing an image from the native white balance of the sensor the raw processor is effectively pushing one channel of data (e.g. blue in this case) and pulling one channel of data (e.g. red in this case). Another way of saying this is that in this scene the ISO of the camera was 6400 but the noise per channel when balanced a bit away from the native red color is more akin to ISO 12,800 on the blue channel and ISO 3200 on the red channel. An alternative approach in this case might have been to use an optical filter to better even out the balance of R vs. G vs. B light hitting the sensor; however, this would mean the ISO of the camera would have to be further increased from it’s already very-high setting of ISO6400 (as we were already at the maximum aperture and minimum shutter speed for hand holding and a tripod would have run counter to the ethos of this shoot, and also would have effected the ability to focus and compose through the optical viewfinder.

Highlight Recovery

In both LightRoom and Capture One the highlight recovery function was used to pull the blown out tones of the hand back into a usable range. In LightRoom this had an odd effect on the color of the model’s skin. In each program there may have been better ways to recover that tone and a raw file is available below for investigating such points by curious readers. Also note that exposure in this image is highly subjective and as an alternative to highlight recovery a straight exposure pull of around 0.5 stops was also considered.

Lens Correction

In both LightRoom and Capture One the lens correction facility for chromatic aberration was attempted to be used to remove the red/purple halo around the black body paint on the model. In Capture One the purple both the ‘purple fringing’ tool and ‘chromatic aberration’ analyzer were very effective at removing these fringe colors without any noticeable detriment elsewhere in the image. In LightRoom neither the profiled correction, nor manual adjustments of ‘chromatic aberration’ or ‘Defringe tool’ had any meaningful effect, and while the selective color de-saturation tool and color noise tool both worked well to remove the red/purple halo around the body paint they had a very negative effect elsewhere in the image.

Luminance Noise Reduction

In both LightRoom and Capture One the luminance noise reduction was kept at zero. Our goal in this image was not to remove the noise but to ensure that the grain/noise of the image was aesthetically pleasing rather than blotchy and digital looking. In both programs the luminance noise reduction sliders quickly made the image artificially smooth – an effect opposite of what we were aiming to accomplish.

Color Noise Reduction

In LightRoom there was low frequency (meaning blob-like) color noise which benefited from an increase to 35-40 from 25. However these settings also reduced some of the subtle color in the red body paint which was essential to the feeling of the shot. If this shot was processed in LightRoom for a final client delivery it seems best to process one layer with Color NR at 25 and one layer with Color NR at 40 and then use Photoshop to blend back in areas negatively impacted by the increased noise reduction. In Capture One there was high frequency (meaning clumped) color noise in the highlights (e.g. the yellow speckles on the nose) which could not be removed using Color NR except at settings high enough to negatively impact the rest of the image. These yellow speckles were easy to remove using the Color Editor’s Skin-Uniformity slider, but we felt this was a bit too much “special attention” for a fair comparison between LightRoom and Capture One as this advanced feature requires a non-basic-user level of skill (though only a few seconds of time). It should also be noted that this color noise only appeared once the highlight recovery was added – otherwise almost no color noise was present in Capture One at the default Color NR setting of 60.

Single Pixel Noise Reduction

[Available in Capture One only] Capture One’s noise reduction includes an independent slider to attack the single hot and stuck pixels that appear in very high ISO dSLR frames. While grain and noise are not always undesirable it’s rare that an image benefits from these single pixels that stand out like sore thumbs. This slider was set to 50.

Surface Noise Reduction

[Available in Capture One only] After some experimentation this tool was left at zero. However, some viewers may find the effect at around 15-20 to be pleasing, especially when associated with a slight increase in the fine grain slider.

Fine Grain

[Available in Capture One only] ‘film like’ is a phrase perhaps over used, but still appropriate in this context. The grain structure of most high speed (black and white) films had a very uniform gaussian feel which was aesthetically pleasing even if it was very grainy. In Capture One we set Fine Grain at 31, but there is a lot of room for personal aesthetics on this slider and much higher settings produced an effect that might be preferred by some viewers. LightRoom should be commended for having a very pleasing fine grain at it’s default setting; though having additional control over the base level of this grain would also be nice, perhaps by allowing a negative setting on the Effects>Grain slider. Also the final effect of grain in each program is noticeably different, equatable to two different high-speed film emulsions; different viewers may prefer one to the other, even strongly as they produce different final looks.

Use of Styles

As pointed out in our article the ability to import images with a style, and the ability to apply a style to any number of images at the same time is a great time saving mechanism. Once the user has decided on a specific set of noise reduction and lens correction tools for Very High ISO dSLR raw files the user can save that style, and in future use simply elect to import the shoot with that style already applied. We’ve saved a style for this example specific to the Canon 5D Mark II at ISO6400 and one of the chromatic-aberation-prone lenses like the Canon 50mm/1.2 and 85mm/1.2 – though this style should serve as a good starting point for other very high ISO settings and other dSLRs. You can download this style below.

Downloads

Downloads Available

• 100% JPG Comparison
• Raw file
• Capture Integration 5D II ISO 6400 Style

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Tech/Legal notes

Versions – This image was shot with a Canon 5D Mark 2 with firmware 1.0.7. It was processed in Capture One 6.0.0 and LightRoom 3.2 (ACR 6.2). Though not of consequence for this comparison it was processed on a first generation Unibody 15″ MacBookPro.