What is Noise in Photography? | Film Grain & Digital Noise

Last updated on May 24th, 2021

Everyone has a camera these days, whether it be a standalone professional DSLR or the always-improving camera phones.

But whatever your tool is, you always want to make your photos aesthetically pleasing by playing with different vantage points or perspectives in photography. However, one thing every picture has — noticeable or not — is digital noise.

What does noise mean in photography? We’ll be discussing noise in this post, in addition to its counterpart grain.

What is Noise in Photography?

By definition, digital noise in photography is the luminance and color aberrations caused by a digital camera and its image sensor when capturing an image.

From a visual viewpoint, noise looks like tiny spots on a picture. All digital photos have some noise in them. Though you sometimes have to zoom in on the photo to notice it with photography software. An excess amount of noise can make an image unpleasing to the eyes.

Now that we know what noise looks like in a photo, we’ll get a bit more technical on the root causes of digital noise.

What Causes Noise in Photos and Digital Cameras?

Digital noise is the randomness or impurities a digital camera’s image sensor records when its capturing light. Heat, electricity, and ISO all have an effect on the overall amount of noise in a picture.

During the image capture phase of a digital camera, the image sensor records streams of light and turns them into pixels (a photo). During this process is when noise is created. As mentioned earlier, there is always some noise in every digital photograph.

The most common cause for noise in photography is low-light settings and high ISO. Often photographers have to use high ISO in low light situations when artificial light is not available. High ISO increases the image sensor’s sensitivity to light, thus increasing digital noise.

When not using a high ISO or flash in low-light settings, often the shutter speed is slowed down and mounted on a tripod to compensate. This causes the image sensor to be exposed longer to light irregularities and thus causing more noise.

The camera sensor sizes also play a part in the role of noise. Full-frame sensors generally have less noise than smaller sensors.

What is Luminance and Color Noise in Photography?

Luminance noise is colorless and is often whitish. On the other hand, color noise, or chromatic or chroma noise, has color, as the name implies. Red is common in color noise.

The easiest way to see or look for digital noise in a picture is to zoom in on a nighttime image.

Furthermore, don’t confuse chromatic aberration with color (chromatic) noise. Chromatic aberration is caused by lens dispersion when not all wavelengths of light are transmitted equally.

What is Grain in Photography?

Tiny metallic crystals cause grain on photographic film (celluloid). Grain is also called granularity. These light-sensitive silver halides convert into pure metallic silver when exposed to light, which is how a picture is photographed on film.

Film grain and digital noise are sometimes used interchangeably as grain and noise.

Many photography software have some sort of add-grain effect to make an image look more vintage or film-like. It’s usually found in the section of the vignette or noise reduction tools.

How to Avoid Noise in Photos

As mentioned earlier, there is always some noise in every photo. However, there are steps we can take to reduce the amount of noise and make it negligible.

First, try to photograph in bright conditions. This helps not needing a high ISO or slow shutter speed.

When bright conditions aren’t possible, a second option is to use a fast lens: a lens with a large aperture of f/2.8 or bigger. A larger aperture allows more light to reach the image sensor. Of course, there can be trade-offs by changing the aperture size, such as depth of field or having to buy a more expensive lens.

Furthermore, a flash helps with photographing in low-light small settings. But not everyone likes carrying a flash. And a flash is not helpful in landscape photography and is often prohibited from being used with wildlife.

The above tips to reduce image noise is only effective in certain conditions. When it comes to specific practices of photography, excess noise is unavoidable.

Take astrophotography, for example, the camera settings are usually ISO 4000+, shutter speed 5+ seconds, and the aperture is wide open. A lot of noise is expected in this situation, and a noise-reduction tool will be required to clean up the image in post. 

The quality of image sensors also plays a large part in noise reduction and detailed pixels. Professional-grade cameras and their image sensors perform better in low-light scenes and produce higher-quality image pixels than entry-level cameras. These pro cameras even have ISO as low as 50.

What is Noise Reduction in Photography?

Noise reduction is the post-editing process to remove or reduce digital noise in an image using photography software.

With noise being prominent in photography, nearly every photography application has a noise-reduction tool.

Some of the popular software are Capture One, Lightroom, and Photoshop. Read the Capture One review for more info.

There are also specialty photography software that are dedicated to noise reduction and only noise reduction. The best noise reduction software right now is Topaz DeNoise AI which uses an AI algorithm. Check out the DeNoise review for more details.

Conclusion

Now that you understand what noise is, I hope you can tweak your photography practice from the field to post-editing and not let noise ruin your images.

Noise has always been part of digital photography like grain has been to film. And that’s not a bad thing. It’s just an obstacle photographers have to work around.