Highest Quality Capture: Workflow Phase I - Black and White in Photoshop CS4 and Photoshop Lightroom - page 73

to prevent signal leakage from one photosite onto another whereby
creating much less noise! Smaller sensors with a higher mega pixel count
unfortunately also equate to more noise in the resulting image data.
• Physical size of the pixels on the sensor: bigger pixels in general translate to
less noise in resulting image data.
• Temperature of the sensor: higher temperatures generate more noise on
the sensor.
• In-camera processing of the signal: camera manufacturer's processing
software can af ect the appearance of noise in an image.
While it is impossible to completely prevent digital noise from happening,
there are a few options that allow you to decrease it signii cantly.
In low light scenes, ISO ratings and shutter speed are the two main variables
to pay attention to. Increasing the ISO creates more internal noise, and
slowing down the shutter allows for more noise to integrate onto the CCD.
The amount of noise each action generates is dif erent for each camera make
and model. Experiment by setting your camera to manual mode and playing
with dif erent shutter speed and ISO combinations to i nd which generates
the least amount of noise for a given situation.
Some camera manufacturers include a built-in feature called noise reduction
which generates and applies specii c algorithms when a slow shutter speed
and/or high ISO setting is used to reduce the amount of noise produced in
the process. Although these algorithms cannot completely remove all noise
altogether, substantial reduction can occur depending on the quality of the
algorithm. The noise is typically removed by an interpolation method that
creates a replacement pixel based on an evaluation of its neighboring pixels.
This, however, typically produces a smoothing ef ect which comes at the
expense of losing i ne image detail.
For most photographers, digital noise can be signii cantly reduced by turning
on your camera's Noise Reduction feature, optimizing the camera settings and
removing noise with some simple techniques. Be warned that many noise
reduction techniques can have the ef ect of blurring or l attening the image.
There is trade-of between losing image detail and decreasing the ef ects of
noise within an image. Keep in mind if you have ever shot a high ISO i lm,
the grain often times of ered the image a wonderful quality that many try to
emulate digitally. Grain can be beautiful, and so too can noise if the image
permits. (See “Reducing Noise with Photoshop”, page 228.)