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