The Digital Darkroom is a series of posts aimed at beginners and those interested in Digital Photography and Editing. In previous weeks we have looked at basic adjustments, curves, editing colour with the HSL/Color panels, black and white toning, split toning, local adjustments and sharpening. This week we are looking at using split toning to help create a rounded image. If you wish to check out previous posts in the series you can do here.
Before looking at tackling noise in Lightroom and Adobe Camera Raw, it is good to understand what digital noise is. Digital cameras create three different types of noise;
Random Noise- which looks like slight pixilation, is a fluctuation in pixels above and below the image intensity. There will always be random noise, but it increases as the ISO is raised. The pattern of random noise changes and will never be the same even when two images are shot with the same settings at the same time. Random noise can be categorised as Luminance and Colour noise.
Fixed Pattern Noise- consists of Hot Pixels, pixels that far surpass the random noise fluctuation. This phenomenon normally is greater with long exposures and is increased when shooting in hotter temperatures. Fixed Pattern Noise will show the same pattern even if two images are taken with the same settings.
Banding- is dependent on your camera. It is created by the camera when it reads the signal from the digital sensor. Banding is most visible in high ISO Images, in the shadows or when an image has been aggressively brightened. I have experienced banding more in Photoshop than in camera but it is dependent on the make and model of the camera.
Fixed pattern noise is the easiest of the noise to remove. The camera has to learn to recognise the pattern and then replace the pixels to create a clean image. It can do this because the Hot Pixels have a repeating pattern. Fixed pattern noise is much less of a problem in the second generation of digital cameras than Random noise.
Random noise although is less objectionable than the other two types it is also the most difficult to remove from an image without degrading the overall image quality. Computers find it hard distinguishing from what is digital noise and what is a pattern or a texture. When attempting to remove random noise you also have a tendency to remove the textures from the image as well. It is this random noise that we are going to eliminate with the Noise sliders in the detail panel.
The key to removing noise is not to remove all noise from a picture but to remove the noise enough that it does not become obtrusive. The effect being the removal of ugly artefacts, leaving “ultra fine grain” and giving a “film feel” or authentic feel to an image.
Random noise appears as both luminance and colour noise. Luminance noise looks a bit like film grain and colour noise is splodges of colour pixels.
You can start reducing noise as you take the picture; correctly expose the image, underexposed images that are pushed afterwards will contain more noise. Use the lowest ISO possible, higher ISO more noise. If you can try to use a tripod and a longer exposure with a lower ISO if the subject is not moving. There are times when you have no choice and have to except that you will be dealing with noisier images.
In the detail panel there are two parts to noise reduction to remove the two areas of Random Noise.
The luminance slider controls the strength of the luminance noise reduction. As a rule of thumb I wouldn’t push it higher than 50 but in extreme cases you can with caution.
The Detail slider is a bit like threshold and decides what constitutes noise. Set at 0 the algorithm says all small pixels lumped together is noise and at 100 nearly all groupings of picxels is considered noise. 50 is a good place to start.
Luminance noise reduction flattens textures as it reduces noise and Contrast helps to counteract the effect keeping details sharp. Adding too much contrast can appear to add more noise back into the image. It also appears to work best with low luminance and details sliders.
When reducing Luminance Noise, the more you increase the strength of the reduction the less effect detail and contrast will have.
This example picture was taken with a 300D the original Canon Rebel camera. At 1600 ISO the image would have been unusable out of camera, but the noise reduction has mean that there is potential for the picture.
Colour noise is noticeable more in high ISO images and is a bit easier to remove. The default of 25 for me has always been pretty good.
Detail works in the same way as it does with luminance as a kind of threshold slider.
Smoothness helps smooth out colour noise that has not been reduced. 50 works pretty well.
Taken at night this image had a lot of noise in the sky and building and the colour noise was a big problem. The basic settings reduced the colour noise altogether leaving the more difficult task of combating Luminance noise. The final adjustment works well and has preserved extremely fine details and will do as the holiday snap it was intended as.
As with sharpening last week, you can also make local adjustments to noise selectively increasing and decreasing the adjustments strength. Increasing the slider increases the strength of the noise adjustment, decreasing the slider reduces the amount of noise reduction. This is plus or minus the adjustment you have already made. I may make a localized reduction if I have lost some detail that I want back and it won’t affect the aesthetic of the entire image. If I crease the noise adjustment this may be in smooth tones that show noise more prevalently and have less details, due to this I don’t mind those tones being flattened.
With this image I used three local adjustments to help with the noise reduction; I used the Radial Adjustment to reduce noise in the background more, the adjustment brush to add noise to the side of the lantern where my noise reduction had removed detail and the gradient tool to add noise to bring back details lost from the radial adjustment.
Add Grain for texture
With all the noise adjustments make your image may look flat even if you have added contrast in the noise reduction process. An idea can be to add a small amount of grain from the effects panel to bring back a bit of texture and make the image more pleasing to the eye.
Photograph for noise
When I first started with digital photography I hated noise and would aggressively reduce it creating images that looked a bit splodgey as a result. I always try and shoot for the lowest ISO possible but I have also learnt what ISO is the maximum I can shoot before I can no longer produce smooth tones after noise reduction. With my first digital camera, Canon 300D, this was 200 ISO not fast at all. With newer cameras you can shoot higher as technology has gotten better. If you do have to shoot at a High ISO to get the shot do. For example when shooting events at my school indoors, I use the noise to my advantage and make it part of the style of the image. There is a reason why people like photographing with 800 and 3200 ISO film because the feel of the grain added something to the picture. A great example of this was a few years ago when I visited a salt mine not too far from where I live. It is dark and ISO 6400 was needed. This is not the highest ISO but the lowest I could shoot with. I used the ISO to help create slightly more grit in an image and make them feel more real than just having smooth tones.
When to Reduce Noise
Noise reduction is part of my sharpening step as I usually do them in tandem. How aggressively you reduce noise is up to you and the image. I would always have a gentle touch when reducing noise as well as previewing the image at 1:1 to see the effect directly on the pixels and then pulling out to see the overall effect.
In next week’s post we will be looking at little tweaks in Lightroom and Adobe Camera Raw that can have a big impact on an image.
If you have any questions or comments please use the comment box below, all are welcome as this series is designed to help people learn how to use Photoshop and Lightroom.
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