Arts and Photography tips and guide

Your digital camera has a sensor that uses millions of tiny pixels to produce that final quality shot that you have become so proud of. When you press the button on your digital camera that takes the photo (shutter button) the exposure process begins, and each pixel collects and stores photons into a cavity. When the exposure phase is done, what is called 'photosites' are closed where your digital camera assesses how many photons fell into each cavity. Now, however many photons are in each cavity, they are placed into different intensity levels, and their precision is calculated by what is called a bit depth (0 - 255 for an 8-bit image).

The Digital Camera Sensor: Light Cavities

But no cavity can tell how much of each color has fallen into it so what I just explained to you above would only be able to create photos on a grayscale level. In order to create color digital photos, each cavity is covered with a filter that only allows a certain color of light in. To my knowledge all digital cameras capture only 1 of the 3 primary colors in each cavity. Which usually calculates out to about 2/3 of the light being removed. So this makes your digital camera estimate the remaining 2 primary colors.

Bayer array

The universal filter most commonly used is "Bayer array". This is made up of alternating rows of blue-green and red-green filters. Each primary color does not receive an equal fraction of the total area because the human eye is more sensitive to green light than both red and blue light. None of the primary colors receive equal portions of the total area because our eyes have been proven to be more sensitive to green light than to red or blue light. Redundancy with green pixels makes your digital photo less noisy with a finer detail, rather than have all colors equal. This is why the green channel is less noisier than the other 2 primary colors.

DEMOSAICING ARTIFACTS

The digital photos you shoot with small-scale detail near the resolution limit of the digital sensor will sometimes confuse the demosaicing algorithm which will give your photo an unrealistic look. The most common artifact is moiré (pronounced "more-ay"), which may appear as repeating patterns, color artifacts or pixels arranges in an unrealistic maze-like pattern.

In the real world digital camera sensors don't actually have photosites which cover the entire surface of the sensor. They only cover just half the total area to accommodate for the other components. Each cavity is shown with peaks between them that direct the photons to one cavity or the other. Digital cameras contain "microlenses" above each photosite to enhance their light-setting ability. These lenses are analogous to funnels which direct photons into the photosite where the photons would otherwise be unused.

Microlens Array Diagram

State of the art microlenses improve the photon signal at each photosite, which create images which have less noise for the same exposure time. Digital camera manufacturers have made improvements in microlens design to reduce or maintain noise in the latest high-resolution digital cameras, despite having smaller photosites due to squeezing more megapixels into the same sensor area.

Omar Erwin has developed a passion for digital photos and its many different avenues. This passion has driven him to write a book not just for beginners of digital cameras and digital photos, but for all who love participating in digital photography. You may get your free copy as a gift by going to http://www.omarerwin.com/gift.html

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