pixel randomizer
Digital noise in photos taken with digital cameras is random pixels scattered all over the picture. It is a similar effect as "grain" in photography film and it degrades the quality of the photo.
Digital noise usually occurs when you take photos in the light (like night shots or indoor dark scenes) or use very slow shutter speeds or high sensitivity modes.
When taking pictures with a digital camera, an electronic sensor (also known as a CCD) built from many tiny pixels is used to measure the light for each pixel. The result is an array of pixels that represent photo.
As with any electronic sensor CCD is not perfect, and includes some noise (also known as white noise to hint in his attribute of randomness). In most of the illumination light is much stronger than the noise. However, the levels of noise in the extreme scenes where the light is low or when requires a high amplification can be significant and result in pixels in the picture data included more noise than light data real photos. Pixels generally appear as random dots or stains on the photo (eg white dots scattered randomly in the photo).
Understanding digital noise in various scenes:
low light (night shots or dark scenes): when the scene is dark the amount of light measured by each pixel of the Convention is low. When the light intensity is very low can be too close to the noise level found naturally in the CCD. In such cases, some pixels may appear as noise because the measured noise level is fairly close to them than the actual light intensity.
shutter speeds: when the shutter remains open for much longer noise will be presented to the photo. A slow shutter speed results in the integration of the Convention more light per pixel. The effect can be easily understood as the CCD "accumulating" light in each pixel and measuring the total light in the time period filling. However, while the CCD is also "accumulating" noise. For that reason in the slow shutter speed photos some pixels appear as noise because of these pixels in the amount of noise integrated is significantly close to or above the actual light measured.
high sensitivity modes: high sensitivity in digital photography is performed by the mechanisms that lead to amplification. The CCD extends the measures taken. However there is no way to expand only the real picture of the light falling on the CCD pixels instead of noise and amplified light are real. The result is that the Convention not only becomes sensitive to light but also with its own noise. When too much amplification is applied some pixels will appear as noise.
While it is impossible to completely prevent digital noise there some options that can significantly reduce it. When taking pictures in low light, like night shots, there are two main parameters to play with: sensitivity and shutter speed. The increased sensitivity creates more internal noise in the CCD, while the slower the shutter allows more noise to integrate on the CCD. The amount of noise generated by both parameters is different. It is recommended that you adjust the camera in manual mode and play with a few different pairs of sensitivity shutter speed to find the one that generates less noise.
Some cameras include a built-called "noise reduction". Noise reduction is implemented by sophisticated software that can identify and eliminate pixel noise. For example, the software can identify the noise pixels in based on its extreme randomness and usually intensity differences between them and their neighboring pixels. Removing noise can be implemented by interpolating a value of replacement pixel based on its neighboring pixels.
If you do not have a built in noise reduction or not working correctly you can use a PC based on the software that removes digital noise. Many photo processing programs include a combination of automatic and manual digital noise removal. Some software packages can also use some photos of the same object of "medium" and help eliminate noise (based on the fact that digital noise is random noise and pixel will be different in each photo taken).
To conclude digital noise is to be understood by any amateur or professional photographer. However, for most photographers digital noise is not a practical problem, even in low light digital noise is usually minimal and can be significantly reduced by simply turning on noise reduction feature of the camera. For professional photographers who shoot in the most extreme conditions of noise digital can be a real problem and can be treated by a combination of optimizing the camera settings and removing noise with software professional.
About the Author:
Ziv Haparnas is a technology veteran and writes about practical technology and science issues. This article can be reprinted and used as long as the resource box including the backlink is included. You can find more information digital photo printing printing and photography in general on printrates.com – a site dedicated to photo printing
Article Source: ArticlesBase.com – Digital Noise – What is It? What Causes It? and How Can I Get Rid of It?
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