| Digital cameras are basically the same as film cameras | | | | Filters are arranged in a pattern called the Bayer |
| in their handling. They both have a lens to focus the | | | | pattern - one row of red, green, red, green (etc.), |
| specific image, a shutter to let light inside the camera, | | | | and the next row of blue, green, blue, green |
| and an aperture to control the amount of light which | | | | (etc).Since each photosite can only be covered with |
| enters the camera.The differences between digital | | | | one coloured filter, computer processing is necessary |
| and traditional photography happen to be after the | | | | to produce a full colored image. This is done by |
| light enters the camera. A traditional camera captures | | | | analyzing a certain pixel and its immediate neighbors |
| the images on film, while a digital camera captures | | | | and producing a composite colour from these |
| the image on an image sensor.Image sensors are | | | | calculations. For example, if a bright red pixel is |
| electronic devices made up of an array of electrodes | | | | surrounded by bright green and bright blue pixels, the |
| (or photosites) which calculate light intensity. The | | | | bright red pixel must undeniably be white, because |
| most universally recognized type of image sensor for | | | | white is the combination of red, blue, and green. This |
| digital cameras is the CCD (Charge-Coupled Device) | | | | process is called demosaicing.After demosaicing the |
| although others such as CMOS and Foveon are | | | | image is adjusted according to the settings on your |
| sometimes used.The number of photosites in the | | | | camera. Most cameras have settings for brightness, |
| image sensor gives the digital camera its megapixel | | | | contrast, and colour saturation. After these |
| (millions of pixels) rating. Each photosite corresponds | | | | adjustments are made some cameras may also apply |
| to a pixel in the final image, so a camera which is | | | | a sharpening algorithm to make the image clearer.The |
| rated at six megapixels, for example, has an image | | | | final step before saving the image on the memory |
| sensor which is 3008 pixels wide by 2000 pixels | | | | card is to compress it. Most cameras use JPEG as a |
| high.When light hits the image sensor it is converted | | | | compression format. This reduces the size of the file |
| into electrical signals which are built-up and fed to an | | | | by eliminating excess data. This information cannot be |
| analog-to-digital (A/D) converter. The A/D converter | | | | recovered, so JPEG is called a 'lossy' format.Several |
| changes the electrical signal into binary numbers which | | | | cameras have the ability to save uncompressed |
| are processed by a computer housed in the camera | | | | images as TIFF files or raw data. Raw data is the |
| body. Once the numbers have been harvested the | | | | original photosite data even before demosaicing. It |
| resulting image is stored on a memory | | | | can be transferred to a computer for processing with |
| card.Photosites can only measure intensity of light -- | | | | special software that will perform all of the |
| not color. In order to produce a colour image, each | | | | processing functions of the camera but with much |
| photosite must be covered with a colored filter which | | | | greater control.Drew Laughlin is a photographer |
| can be red, blue, or green. These are the three | | | | extraordinaire. Digital Photography is a true passion of |
| primary colors which can be combined to produce | | | | Drew's and he loves sharing his research, reviews and |
| any other colour including white.The colored filters are | | | | information to help people become better |
| arranged in a grid so that there are twice as many | | | | photographers and help them choose the best digital |
| green filters as there are red or blue. This is because | | | | camera for their needs. |
| the human eye is twice as sensitive to green light. | | | | |