How To Reduce Digital Noise In Your High ISO Images

One of the great advantages of digital cameras is that the ISO rating can be changed for each and every shot you take. The problem is that even with DSLRs, once you get up to ISO1600 digital noise starts to be very noticeable in the image. It’s even worse in compact cameras where smaller sensors and lenses create additional problems. Most cameras have some form of noise-suppression built in but when it’s turned up to the kind of level required to nullify high ISO noise, it tends to turn the photo to mush.

Unfortunately, there are simply some situations where you have no choice but to push the ISO up. There simply isn’t enough light in places like interiors on overcast days, in caves, at gigs in darkened rooms and the like. In order to get the image at all, the ISO has to be increased, making the camera more sensitive to light. The problem of the noise that comes as a result is one to tackle back on the computer. Here we're using MacPhun's Noiseless for the Mac as a standalone app.

Noiseless Step-By-Step Tutorial: 

Open Up Your Noisy Image

This image was taken in a cave system in Derbyshire and required the ISO cranking up to ISO3200 just to get this shot because there was so little light. The result is high levels of noise throughout so the challenge is to not lose all the detail while removing it. Load the image and select a dual screen format that suits the image orientation. Side-by-side suits vertical images, as seen here.

Zoom In To 200%

Noiseless is different from most other MacPhun filters in that it doesn’t use layers but it does have a basic cropping system. So, if you need to rotate and then crop an image you can although, if the image is distorted you are better using photo editing software to correct it there. Zoom into 200% so you can see the noise and the filter effects on it.

Adjust The Noise 

In the Presets pane on the right, there are a number of settings from Lightest, which does very little, to Extreme, which does an awful lot. Click on Medium to start with and see what effect it has on the image. Drag the screen around to see different parts. If not happy, select a different preset until you get the one closest to the ideal balance between noise reduction and losing detail or softening the photo.

Find Structure

Click on Adjust to see the parameters that go into the Preset used. There are sections for Noise Reduction, Structure, Details and Filter. The most significant for putting impact back into the image is Structure which adds local contrast. There’s a big different between +50 and +100 but it can make the image noisy again. Experiment with this slider to get a good compromise.

Noise Reduction 

Sometimes the processing can be too aggressive and create patterns in the image, like those found in heavily compressed JPEG images. If that’s the case and you don’t want to reduce the Overall Opacity of the effect because it lets the noise back in, then look under Noise Reduction and increase the Area and Strength of the Smoothing filter.

Colour Noise & Luminance Noise 

The other two main settings to try tweaking are also under Noise Reduction. These are for colour noise, which you tend to get from long exposures when it’s dark, or luminance noise, which is more likely to come from high ISO ratings. Try increasing the settings for either of these to increase the amount of reduction being applied. When happy, export the image.

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After

Try For Free

If you want to have a go at the above tutorial, you can download a trial version of the Noiseless App from the Macphun website for free.