Discover How To Clean Up Images Plagued By Dirt And Noise

While increasing the ISO rating on the camera creates an accepted trade-off between getting more shutter speed at the expense of additional noise in the image, long exposures can also cause problems for image quality. It’s standard practice that to shoot long exposures at dusk, the camera is tripod-mounted and if there is water or sea involved, the longer the shutter is open, the better for the resulting image as it smooths the waves out. However, at dusk you start to play a dangerous game because long exposures where there isn’t quite enough light tends to produce blocks of green-flavoured noise or variation in bands of solid colour.

Once the image has been brightened up and the colours tweaked, any variation in the tones will be magnified and suddenly that colour noise is all too apparent. A related problem is a physical one. Every time you change a lens, dirt gets in. Now modern chips come with all manner of dirt removing strategies, but in the end, it’s going to start to collect if you don’t use a blower on it regularly, or have it professionally cleaned. At this point, images shot when the sensor has dirt on it now have a double problem; both long exposure or under exposure noise and specks of dirt. They are all image defects that can be tackled in one go with MacPhun’s Noiseless Pro standalone app and Photoshop-compatible plug-in.

Noiseless Pro Step-By-Step Tutorial: 

Load The Image 

Load the image into Photoshop and start the Noiseless plug-in. The image used here has both colour noise and dirt on the sensor and as such represents a challenge to clean up while retaining enough detail. Split the screen into the before and after views by click on the dual view icon. You will need to see the effects of the noise-reduction as it is applied.

Experiment With Presets 

The idea is to remove all the noise and then as much dirt as possible. Any dirt left will have to be removed using standard Photoshop tools. Experiment with the Presets until you have one that is strong enough to remove all the noise, even if there is a loss of detail. Then click on Adjust.

Luminance Adjustment

Most long exposure noise is likely to come out as colour noise, rather than luminance so here’s where you can start to put some detail back into the photo. Reduce the Luminance > Coarse setting and then the Luminance > Fine settings until the noise starts to appear again. You should be able to restore a decent amount of detail like this.

Boost Contrast 

The Structure section is for putting local contrast back into the image. Smoothing out the noise can reduce contrast, so increase the Amount to make it more contrasty. The Protection stops the shadows and highlights from being lost depending on how much you apply it. If the image doesn’t have bright highlights or dark, shadow areas, then reduce this to zero and simply use the Amount slider.

Details Are Important 

For getting more actual detail back into structures like the castle here, then the Details section is where to tweak next. Increase the Amount to restore detail, even up to +100, but watch out for halos on objects, from in-camera sharpening, becoming too apparent. Protection again clips the effect from the extremes of the tonal range, the more it is applied, the less effective the Amount becomes. The third factor is Masking. If Details starts to create distinct artefacts in single colour areas like the sky, increase this until they are removed.

Filter Section 

The final parameter section, Filter is very useful because it means you can apply the noise-reduction depending on shadow, mid-tone or highlight areas. In this image, the only highlights are the castle lights. The sky and sea are midtones so that needs to be applied strongly. The castle and ground are shadow details so you can filter back the effect here and restore quite a bit of detail without bringing a noticeable amount of noise back. After that, apply the clean up and tackle the remaining dirt in Photoshop itself.

Before 

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.