When shooting in low-light conditions, the camera sensor is forced to amplify the signal from each pixel, which introduces noise.

Long exposure photography is a technique for reducing noise by capturing multiple images at a slow shutter speed and then combining them into a single image.

In-camera noise reduction typically works by applying a combination of techniques, including blurring, sharpening, and contrast enhancement, to reduce the visibility of noise.

Post-processing noise reduction software typically works by applying a combination of techniques, including blurring, sharpening, and contrast enhancement, to reduce the visibility of noise.

Noise Ninja is a standalone noise reduction software program that is no longer actively developed.

The best noise reduction settings will vary depending on the image and the amount of noise present. It is important to experiment with different settings to find the best results for each image.

Increasing the ISO will increase the amount of noise in the image.

Using a tripod, shooting in RAW format, and using a lens with a wide aperture are all common techniques for reducing noise in high-ISO photography.

Using a tripod does not increase the amount of light that reaches the sensor.

Shooting in RAW format gives you more flexibility in post-processing, reduces the amount of noise in the image, and allows you to use a higher ISO.

Using a lens with a wide aperture allows you to use a faster shutter speed, reduces the amount of noise in the image, and increases the amount of light that reaches the sensor.

Gaussian noise is not a common type of noise in high-ISO photography.

Purple-green noise is not a common type of chrominance noise in high-ISO photography.

Gaussian noise is not a common type of luminance noise in high-ISO photography.

Unsharp mask is not a common technique for reducing salt-and-pepper noise in high-ISO photography.