Types of Noise in Photography
Luminance Noise
Luminance noise is the variation in brightness of individual pixels that creates a characteristic grainy structure in a photograph. Noise in photographs is often compared to grain in analogue photography. Unlike chromatic noise, luminance noise can sometimes add an artistic touch to photographs, especially in black and white photography.
Chromatic Noise
Chromatic noise manifests itself as randomly distributed coloured dots in a photograph, particularly visible in the dark areas of the image. This type of noise is usually more problematic than luminance noise, as it introduces unwanted colours into the image, which can significantly reduce its quality.
Where Does Noise Come From?
High ISO
ISO is one of the main contributors to noise. The higher the ISO value, the more likely there is to be noise in photography. This is because increasing the sensitivity of the sensor involves an amplification of the electrical signal, which also leads to an amplification of noise.
Long Exposure Times
During long exposures, the camera sensor heats up, which can lead to so-called thermal noise. This photo noise is particularly noticeable during night photography or astrophotography, where exposure times can reach tens of seconds or even minutes.
Sensor Quality
The size and quality of the sensor have a significant impact on the noise in the images. In general, the larger the sensor and the larger the pixels, the better it handles noise. Therefore, full-frame cameras usually offer better image quality at high ISOs than cameras with smaller sensors.
FAQ
What are the three common types of image noise?
The three main types of image noise are shot noise (random brightness variations), color noise (random color variations), and fixed pattern noise (consistent patterns from sensor defects). Each type can affect image quality differently and requires specific approaches for reduction.
What is shot noise in photography?
Shot noise is a fundamental type of image noise caused by the random nature of light photons hitting the camera sensor. It appears as random brightness variations and becomes more noticeable in low-light conditions or with high ISO settings.
How much noise is acceptable in photography?
Acceptable noise in photography levels vary by photo genre and intended use. Portrait and product photography typically require minimal noise (ISO 100-800), while documentary or street photography can tolerate more noise (up to ISO 3200-6400). The key is maintaining detail clarity.
How do you remove noise from photography?
Noise can be reduced using specialized software like Lightroom, DxO PhotoLab, or Topaz DeNoise AI. In-camera noise reduction, shooting at lower ISO settings, and proper exposure techniques also help minimize noise. Multiple shot averaging can be effective for static subjects.
Why is noise bad in photography?
Noise degrades image quality by reducing sharpness, detail, and color accuracy. It can distract from the subject and make images appear unprofessional, particularly in prints or large displays. Excessive noise can also make post-processing more challenging.
At what ISO do pictures get grainy?
Image graininess typically becomes noticeable above ISO 800 in entry-level cameras and ISO 1600-3200 in professional cameras. The exact threshold varies by camera model, sensor size, and lighting conditions. Newer cameras generally handle high ISO better than older models.
How to fix a grainy camera?
To minimize camera grain, shoot at the lowest possible ISO, use proper exposure settings, and ensure adequate lighting. Use a tripod for longer exposures, invest in fast lenses (large aperture), and shoot in RAW format for better noise control in post-processing.
How to Reduce Noise in image processing?
During image processing, reduce noise by using dedicated noise reduction software, applying selective noise reduction to preserve details, and balancing noise reduction with sharpness. Consider luminance and color noise separately for best results.
How Do You Minimise Noise in Your Images?
4 Basic Techniques
- Use the lowest possible ISO suitable for the conditions
- Exposephotos correctly – underexposed photos need brightness boosting in post production, which accentuates noise
- Use a tripod in low light so you can use longer exposure times without raising the ISO
- Shoot in RAW for greater control over noise reduction in post-production
Advanced Techniques
Multiple exposures can help reduce noise. By taking a series of identical images and then combining them in specialist software, noise levels can be significantly reduced while maintaining image detail.
Noise Reduction in Retouching
Image Editing Programmes
Photo editing apps offer advanced noise reduction tools. Adobe Lightroom, Capture One or DxO PhotoLab have specialised algorithms that can effectively reduce noise while preserving image detail.
Selective Noise Reduction
The key to effective noise reduction is a selective approach. Different areas of a photo may require different levels of noise reduction. For example, smooth surfaces like the sky may be subjected to stronger noise reduction, while areas with a lot of detail require a softer approach.
When Might Noise Be Desirable?
Paradoxically, in some situations noise can be a desirable element. In fine art or black-and-white photography, properly controlled noise can add a character to photographs, reminiscent of the grain known from analogue photography. The key is to use this effect consciously.
Noise in Different Conditions
Low-Light Photography
In low-light conditions, noise presents a particular challenge. Understanding the trade-offs between ISO, exposure time and aperture is key to achieving optimum image quality. Sometimes it is better to allow a certain level of noise than to risk moving the photo with too long an exposure time.
Studio Photography
In studio conditions, where we have full control over the lighting, it is easier to avoid noise. Adequate lighting allows you to use low ISO values, resulting in a cleaner image. However, even in the studio, it is useful to know techniques for dealing with noise, especially for low-key photography.
Noise in Photography vs. Quality
Sharpness
Noise has a direct impact on the detail of your photos. The more noise, the harder it is to see fine detail in a photograph. This is particularly important for photos that will be printed in large format or require precise detail.
Colour Reproduction
Chromatic noise in photography can significantly affect colour reproduction. Random coloured pixels disrupt the natural colours of a photo, which is particularly problematic in portrait or product photography, where accurate colour reproduction is crucial.
Will the Problem of Noise Disappear?
Today, cameras are equipped with increasingly sophisticated noise reduction systems. Artificial intelligence and machine learning are being used to intelligently analyse and reduce noise in photography right at the camera processing stage. This allows for cleaner images even at high ISO values. Nevertheless, we assume that the process will at some point reach a level close to 100% effectiveness.
