WHAT IS NOISE AND HOW TO REDUCE IT

Noise are called those grainy spots,those annoying color speckles that appear where they

shouldn't be.For example instead of blue sky you notice some pink ,purple or some other colored pixels,and these can occur when your photo contain many shadows or a brilliant patch of a pristine sky.Noise can be vary problematic for your photos as sometimes it an destroy them or the stock sites don't approve them if you intend to sell.So here we are going to give you some tips on how to avoid all these problems.
1. Choose the best camera you can afford-Your camera can make a difference on your photography noise.One of the major difference between a consumer digital camera and a dSLR ( digital Single Lens Reflex) is that the first one produces images with a lot of noise when using high ISOs and long exposure times,the second one is practically noise free.IN digital cameras this noise can come from a variety of sources.The main source of image noise is the sensor and it can be unavoidable.The individual photocells on a digital camera sensor are incredibly small, especially with high-resolution compact camera sensors. This is the main reason that physically larger sensors are much better than smaller ones. The individual photocells are larger and collect proportionately more photons during the exposure, reducing the effects of these statistical variations and producing an inherently higher signal to noise ratio. Some of it is internal noise generated by imperfections in the electronic components of which the camera is made, or simply as a by-product of their normal operation. For instance, capacitors generate a small amount of signal noise as they charge and discharge.Circuit noise can be minimized by efficient circuit design, superior manufacturing techniques and rigorous quality control. Unfortunately some cheaper camera brands, or even budget camera ranges from better-known brands, may use components that are built down to a price rather than up to a standard, which is why these types of camera generally produce noisier images than more expensive models.
2.Use the lowest ISO possible- ISO which deals with measuring the sensitivity of the image sensor, should almost always be set low for stock photography purposes, as any grain found in the image will likely cause it to be rejected. When we shoot with high ISO sensitivity,we increase the amount by which the signals from photocells are amplified.But the amplification process can't tell the difference between image signal and noise ,so the noise gets amplified too.If the signal to noise ratio was already very low then this just produces more noise without improving the image.That is why high ISO sensitivity images have always more noise than the ones taken at low ISO sensitivity. There are cases where a photographer wants a certain amount of noise in a photo and this is not wrong at all.

3.Avoid longer exposures-Longer exposures tend to lead to noise issues in your images. If you must have the option of using high ISOs (e.g. to capture fast action in low-light situations), then get a dSLR.Also get a good tripod cause you will need one. Sometimes, due to irregularities in the manufacturing process, errors in signal transmission and other factors, the photocells that make up the sensor may not all respond to light to an equal degree, causing single pixels to appear very bright or very dark. The charge build-up over a longer exposure makes this problem more noticeable. This type of noise can usually be remedied by applying a masking filter during image processing. Most modern cameras do this automatically, but it can be a problem on many older models.

4.Get the right exposure when you shoot- Use a light meter to ensure that the image is properly exposed.If you have significantly lighten the image in an image editing program,most probably the midtones and shadows will contain a great amount of noise.

5.Noise reduction software-There are lot of software that can do that,for ex you can use Photoshop, Lightroom ,Bridge or if you want something faster you can use Neat image etc.The better way to reduce noise during post processing for example with Adobe photoshop is to use smoothing filters that can be different types but the most commonly used is the one called Median filter.This works by comparing each pixels to the ones surrounding it, and if is has a brightness value that is radically different from its neighbors, then it is replaced by an artificial pixel with the average value of the neighbor pixels.This method is great in reducing noise but also it causes some negative effect such as reducing detail and contrast so you have to be careful with the value of the filter you want to use.In the end the most effective way to have less noise in your photos is to use larger and more sensitive photocells,so to use SLRs camera and getting good shoots from the beginning ,so you will spent less time in post processing.