Photoshop noise reduction

by Design Workshop Sydney

Digital photographs created in low light or with high ISO settings or a cheap camera will create noise in the image. We can perform a lot of noise reduction in Photoshop. This is one of the many topics we explore in our Adobe Photoshop coursesPrint
The Reduce Noise filter was first introduced in Photoshop’s CS2 version, so it’s been around for a while. Note that whilst noise cannot be removed completely, we can significantly reduce it. The Reduce Noise filter deals with three types of noise: luminance, color and JPEG artifacts. Luminance consists of dots of varying degrees of brightness. Colour noise is made up of red, green and blue dots or splotches, often on the tonal edges of objects in the image, like areas of shadow and light. And JPEG artifacts are created during JPEG compression.
Before adding a filter in Photoshop it’s always a good idea to go to Filter > Convert for Smart Filters, which will allow for later editing. Then select Filter > Noise > Reduce Noise. A dialog box with a large preview appears. Click on the plus and minus buttons to zoom in and out.
The Strength and Preserve details sliders are used to remove luminance artifacts. We also have Reduce Colour and Sharpen Details – keep the latter at zero since sharpening is better done with Photoshop’s Unsharp Mask filter. And lastly, we have Remove JPEG Artifacts.
Firstly, turn all the sliders to zero and untick the Remove JPEG Artifact box. Then turn the Remove Colour Noise up until you see the colour artifacts blend into the image. Click and hold inside the preview image to see a before & after effect.
Next is Luminance noise, which consists of various levels of brightness. Zoom in to see better. Move the Strength slider up until the noise disappears, again doing a periodic before and after effect to check. Then drag the Preserve Details slider up – you are trying to get a good balance between noise and detail.
For more refined options, turn Strength to zero and go to the Advanced tab – here we can remove noise channel by channel. Click the Per Channel tab. Blue is often the noisiest channel. Repeat the method above for each channel. Go back to the Overall tab  and fine-tune the Strength and Preserve Details sliders.
JPEG compression artifacts make the image look like it’s made up of 8×8 pixel squares. And each time an image is saved as a JPEG (and thus compressed) the quality gets worse. Tick the Remove JPEG Artifact box. Hit OK when you’re happy with the result. Note that by converting for Smart Filters a small icon is displayed on the Photoshop layer; if you need to edit the effect later simply double-click on this icon to enter the Remove Noise Filter dialog again.
Many more tips and techniques can be found at the Adobe website. And see many examples of our clients’ work on our Facebook page.
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