DxO Noise Engine :
|
DxO Optic Pro's literature states that DxO Noise is a hard-ware model based correction. They specifically tailored by DxO Labs for each camera, and so this correction will only be performed for images from cameras that have been calibrated by DxO. DxO labs claim a 2-stop improvement in the noise level, and the software has been designed to retain maximum detail in the image. |
|
The DxO Noise palette, allows you to control the following aspects of digital noise:
- Luminance Noise Correction
- Fine Detail Preservation
- Chrominance Noise Correction
- Impulse Noise Correction
- Gray Equalizer
Fine Detail Preservation will preserve a greater amount of fine detail in the photo,
(at the expense of some residual noise), to avoid that plastic look of over-processed images.Impulse Noise Correction is randomly occurring noise. It is however not corrected for on raw images, and will be grayed out when processing raw images.
The Grey Equalizer tab cleans up unwanted coloured noise from the mid-tones - at the expense of slightly desaturating the mid-tones.
In testing the noise reduction capabilities of this software, I found that it is difficult making a direct comparison to how other programs handle noise, since DxO Optics Pro brings into play other corrections and adjustments. Especially the changes made by the DxO Lighting palette itself, causes the image to look substantially different in that it automatically brings out a lot more shadow detail.
Please note: This isn't a quantitative test - but just an indication of how DxO stacks up when you look at the details.
This sequence of images are all 100% crops of a portrait I did of my daughter, using available light. The image was repeated for 800 iso, 1600 iso and 3200 iso. Nikon D2x and 70-200mm f2.8 VR.
The first shows the difference between using DxO and the image with no noise reduction at all.
The slight change to the image is due to the optical correction that DxO applies. (Keep in mind that we're looking at 100% crops and that the differences might be marginal with small enlargements.)
1600 iso |
a: Nikon Capture with no noise reduction |
The DxO image does look noticeably cleaner, but the sharpening applied introduces some slight artifacts, especially if you look at the eyelashes.
For the next series of images, I compare DxO with all settings enabled, against the version from Neat Image (on a jpg converted via ACR.) This will give us a more precise idea of how DxO Optics Pro compares to excellent noise reduction software such as Neat Image.
800 iso - DxO Optics Pro - Neat Image
1600 iso - DxO Optics Pro - Neat Image
3200 iso - DxO Optics Pro - Neat Image
My personal preference here is for the DxO version of the 1600 iso image. But with the 3200 iso image, I prefer the softer look of Neat Image since the noise reduction of DxO creates noticeable artifacts which doesn't look pleasing.
Extreme test:
Back to this image shown on a previous page - we'll be able to see how DxO's noise reduction handles the dark interior. Since the darker areas will be enhanced with DxO Lighting, the noise reduction applied will look different than it would to an image with less contrast.
(Nikon D2x; 12-24mm f4 DX, used at 12mm; 1/6th sec @ f5.6 @ 1600 iso)
Here's how DxO changes the image from a basic conversion in Adobe Camera Raw:
(ACR settings: 0% luminance smoothing, 25% chrominance noise reduction.)
It is impressive in how DxO opens up the image, but we'll have to look at the detail at 100% (or more) to see the actual effect of noise reduction.
 |
 |
The first image is of ACR at 0% luminance smoothing, and 25% chroma noise reduction.
The second image is via DxO but without DxO Optics and DxO Lighting enabled - just so we can see how the noise reduction looks.
 |
 |
The lefthand image here is a 100% crop of the DxO converted raw file, but with all the settings enabled (on auto). The next image is of the DxO converted file without DxO lighting enabled, since this boosts the shadow areas, and will affect how the noise reduction works.
 |
 |
The final two images are with Neat Image doing the noise reduction - firstly on a JPG converted from the raw file via ACR. And the following image is of the DxO converted JPG (with DxO Noise off) and then processed in Neat Image.
Conclusion of extreme example results:
The DxO Optics controls do boost the shadow areas considerably, and this will give a brighter and more eye-catching image - but at the cost of making the noisier areas more pronounced. There's a distinct trade-off here. In running the jpgs through Neat Image, a cleaner result was possible, but at the cost of detail which is smoothed out.
What I take from this is that if you are working on an image taken at a high iso, and with lots of shadow areas, it might be better to turn off the auto settings and nudge the image to where you want. It is more work, but the results might be better. As it is, DxO Optics enhanced the dark image really well, and I like the results - but if the image were to be enlarged considerably, then the artifacts might show, and an image with less aggressive manipulation might be better to work with.
To my eye the best results were achieved with the DxO enhanced image with noise reduction off, and then processed through Neat Image.
This extreme example is the only type of image where the automatic adjustment and enhancement of DxO Optics Pro fell down slightly. So overall, the software is still a remarkable tool for the digital photographer. For the rest of my conclusion, return to the intro page.
Neil van Niekerk