In this post, we’re looking at Noise in photography, what causes photographic Noise, and the steps you can take to avoid grain-infested photos. Alternatively, if the damage is already done, I’ll point you toward the best photo noise reduction applications you can buy today.
Table of Contents
- What is Noise in Photography
- What causes Photographic Noise
- Noisey Photos Explained
- How to avoid Noise in photography
- How to fix noisy photos.
What is Noise in Photography
Photographic Noise is present in all photos and adds a grain-like texture to your image as it becomes more severe. In milder cases, a little photo noise is hardly intrusive, and you might even like it.
But at its worse, photo noise can completely take over your photo by introducing strange colors and obscuring detail.
What causes Photographic Noise
Photo Noise is an unavoidable consequence of using a digital circuit. As your camera’s image sensor is exposed to light, your camera sensor reacts to the incoming photons by producing an electronic charge.
And the greater the amount of light your camera’s sensor receives, the greater the electronic charge produced, and the brighter your photo will be. Read How does a Camera Image Sensor Work?
Now, this process is performed for each of your sensor’s photo sites. So if you have a 20-megapixel camera, your camera’s sensor has 20 million photo sites, each interpreting the amount of light it receives into an electronic charge. Ultimately, these 20 million signals of various degrees of brightness are all threaded together and combined to create a single 20-megapixel photo.
Unfortunately, imperfections in circuitry, ambient temperatures, exposure length, and quantum effects all corrupt the signal, meaning the digital signal is no longer a perfect representation of the scene you’ve just snapped.
Specifically, some pixels will be a little brighter than they should be, and others will be a little darker, resulting in the grain-like aesthetic we all know and loathe. This is known as Random Noise.
Yet despite this ever-occurring corruption, you’ll not always see it. Many of your photos will be as clean as a whistle. This is where the Signal Noise Ratio comes into play.
Noisey Photos Explained
Since Noise is unavoidable and ever-present, why should some photos be noisy and others clean? Well, that’s down to your photo’s signal-to-noise ratio, or SNR for short, with the signal being the quantity of light your camera’s sensor receives.
Why your photos are not noisy
When taking a photo on a bright sunny day – your camera’s sensor receives abundant light. In other words, it gets a strong signal.
In this situation, the amount of signal (light) captured by your camera’s sensor is vastly greater than the amount of random noise your camera’s circuitry is likely to produce. As a result, you have a very strong signal-to-noise ratio.
This means your photo will still have Noise, but the Noise will be overwhelmed by the strong signal to the point of being rendered negligible or invisible.
Why are your photos noisy?
If you are taking a photo inside a dark room, there may be insufficient light or signal to produce a reasonably bright image. In these cases, your camera uses artificial means to boost your photo’s brightness.
These increases are measured in ISO with higher ISO numbers, such as ISO6400, representing a 64-fold amplification. However, amplification boosts both signal and Noise. Read What is Camera ISO in Photography.
So while your photo is now brighter, so is the Noise. As a result, Noise now exists in far greater quantity, becoming more visible and problematic. This is known as a low signal-to-noise ratio in that the photo and its Noise might compete for your eye’s attention on equal terms.
How to avoid Noise in photography
To avoid taking noisy photos, you need as much light as possible. With sufficient light, you’ll be able to capture a bright image without dialing up your camera’s ISO and amplifying your photo’s noise levels. When it comes to capturing more light in photography, you have four options.
#1 Take Photos in Better Light
The most obvious option is to take photos in well-lit environments. For example, reserve taking your photo until mid-day, when you’re outside or near a window. Alternatively, you can use a flash.
#2 Use a Slower Shutter Speed
Dropping your shutter speed from 1/1000th to 1/500th of second doubles the amount of time your camera’s sensor is exposed to the light, thus, doubling your photo’s brightness.
Unfortunately, slower shutter speeds can result in a blurred photo due to the involuntary movement of your hands shaking the camera during exposure. You can work around camera shake with an image-stabilized lens/camera or a tripod.
However, neither a tripod nor image stabilization will help you take a sharp photo of a moving subject. To avoid motion blur, you need fast light-starved shutter speeds and a fast large aperture lens. Read What is Shutter Speed in Photography.
#3 Use a fast large-aperture lens
A fast lens can pass more light at any moment than a slower one. For instance, a lens with a large F2 aperture will flood your camera’s sensor with four times as much light as a lens with an F4 aperture. Read What is Aperture in Photography.
Such lenses are popular with sports photographers who need lots of light despite being forced to use fast light-starved shutter speeds to capture sharp photos of moving subjects. Read What is a Fast Lens.
#4 Use a camera with a larger sensor.
A larger sensor has a larger surface area enabling it to capture more light in any given moment than a small sensor with a small surface area. Just like a wider bucket will capture more rainwater more quickly than a narrow bucket.
For instance, a full-frame sensor has four times the surface area as a Micro Four Third sensor and, thus, captures four times as much light. As a result, you can amplify a full-frame camera’s image four-fold (ISO400) and still end up with an image comparable to the best possible Micro Four Thirds image.
For this reason, full-frame cameras are often used by sports photographers, astrophotographers, and anyone else who needs to capture as much light as possible in a short time. Read Camera Sensor Sizes Compared.
How to fix noisy photos.
You can fix your noisy photos using noise reduction software. And thanks to artificial intelligence, noise reduction applications are better than ever. Unlike the kind of detail-sapping traditional noise reduction built into most cameras and photo editors, AI-powered noise reduction can remove Noise while enhancing detail.
As you can see from the sample above (Topaz Photo AI), AI-powered noise reduction is a game-changer and an extremely cheap alternative to buying a fast lens or a large-sensor camera. Read Best Noise Reduction Applications
Get Discounts on Photo Editing Software
Subscribe to my weekly newsletter and be notified of deals and discounts on photography software from ON1, Adobe, Luminar, and more. Spam Promise: Just one email a week, and there’s an unsubscribe link on every email.
Noise is ever present in photos. But so long your camera gets enough light, the Noise will be negligible to invisible. But, if you’re shooting in poor light and you must use a higher ISO to produce a sufficiently bright photo, your camera will amplify your photo’s image and Noise in equal measure.
Thus, to avoid taking noisy photos, you must ensure your sensor gets all the light it needs by taking pictures in good light and with a suitably slow shutter speed. And if that’s not practical, you can invest money in faster and brighter large-aperture lenses and/or a camera with a larger sensor.
But if the damage is done and you have a noisy photo to fix, the best noise reduction applications, such as Topaz Denoise AI, can perform miracles and are vastly more affordable than a hardware upgrade.
Nevertheless, noise reduction is a safety net you can often avoid falling into so long as you apply good technique and use suitable equipment.