Often an image will not appear noisy until you zoom in where the noise becomes much more noticeable. You might find that the shadows and darker areas contain heavier noise than the mid-tones and highlights; when the shadows are brightened the noise becomes even worse. The good news is that with Topaz DeNoise it is possible to reduce shadow noise without affecting other tonal areas and softening them up.Marqués de Riscal winery, Elciego, Image © Nichole Paschal
Looking at the above image, when zoomed out there isn’t any heavy significant noise. At a closer view the noise becomes more visible in the shadows and darker areas. Specifically you can see contrast heavy noise, luma noise (grain), and color noise on top of that.Noticeable noise
DeNoise can be used to remove shadow noise while retaining detail in the highlights and mid-tones, all within a couple of minutes. You’ll want to conduct noise reduction at the beginning of your workflow, as making any other photo adjustments to the image might worsen this noise if it is not cleaned up first.
Reduce Shadow Noise with DeNoise
1. Open DeNoise and press ‘Reset’ (located in the bottom right corner of the interface).
2. Change your view to 100% or 200% and set your viewfinder to show a variety of tonal ranges (mid-tones, highlights and shadows).View scale and navigator
3. Now look at the right hand panel including all of the individual sliders. You’ll notice the ‘Overall Strength’ slider which affects all areas of tonal range within the image. Increase this only a tad bit, enough to reduce noise in highlights and mid tones without softening the image or removing detail.Minor increase in overall strength
4. Change your preview mode to ‘Luma’, which will take the color information out, showing grayscale information and luminance noise.Luma (grayscale) mode
5. To see the shadow noise better, turn the Auto Brighten on to normal or strong.
6. Take the ‘Correct Black Level’ to 0 (by default it is set to 1). Often if you adjust shadow noise with this turned on, you might find that the image will become posterized in the shadow areas as noise is removed.
7. Now fine tune the shadows by taking the ‘Adjust Shadow’ slider to the right, which will remove shadow noise, while leaving mid-tones and highlights alone.Before and after shadow adjustments
8. Turn the auto brighten off. If you see a magenta haze in the shadows, increase the ‘Correct Black Level’ a tad bit to correct this.
9. Switch the view mode to Red to see the red channel information. Increase the ‘Adjust Color- Red’ slider until you see the mid-tone areas smoothed out, suppressing the red noise.Red channel mode
10. Once you are happy with the red channel, do the same with the Blue channel by switching the mode to Blue. Increase the slider if there is noise or decrease it if the blue channel appears too smooth.Blue channel mode
11. Now view the image in Color mode and increase the clean color to somewhere between 0.20-0.30 to reduce any leftover color noise in the image.Color mode
12. Once you are finished correcting color and luminance noise, go back to RGB mode. Press the spacebar to toggle back and forth between before and after.
13. If you notice that your image has softened up, to bring back details, increase the Detail Recovery slider a tiny bit, but not too much as it will sharpen any leftover noise. Additionally you can add back grain if you think the image is still too smooth, which will add texture and bring back the illusion of detail without sharpening.
14. If you wish to create a preset out of the settings to apply to future images, you may do so by clicking on the settings icon in the bottom left corner and clicking ‘Save’. This will save the settings as a preset in the left hand panel.
When saving a preset in Topaz DeNoise, there is an option to select ‘Relative to Noise Estimate’ or ‘Absolute’. The Absolute and Relative parameter settings determine how the parameter settings from your previous DeNoise session are viewed. Absolute will set the preset at the same exact slider values that were applied to the last image you processed with DeNoise. This is ideal for batch processing images with similar characteristics such as ISO. Selecting the Relative setting will shift the slider values, giving you an estimate of the image and noise settings based on your last session.
You can now see that the shadow noise in this image has been removed without affecting the details in the mid-tones and highlights.
I hope that you now have a better idea of how to selectively reduce shadow noise without affecting the entire image. If you do not own DeNoise, but want to try this out, you can download the software from our downloads page to experiment (you won’t be able to save the image back to your host editor without a trial key in which you can request here). Be sure to share your results with us on Facebook and Twitter!