What is Digital Photography, Lauren Ratliff Photography Dallas, TX

What is Digital Photography?

Digital photography is a form of photography that utilizes digital technology to make digital images of subjects. Until the advent of digital technology, photography used photographic film to create images which could be made visible by photographic processing. Digital images can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing.

Digital photography is one of several forms of digital imaging. Digital images are also created by non-photographic equipment such as computer tomography scanners and radio telescopes. Digital images can also be made by scanning conventional photographic images.

Performance metrics

 The quality of a digital image is the sum of various factors, many of which are similar to film cameras. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors, though it is the most heavily marketed. Pixel count metrics were created by the marketing organizations of digital camera manufacturers because consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera. The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is the most critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.

• Lens quality: resolution, distortion, dispersion (see Lens (optics))
• Capture medium: CMOS, CCD, Negative film, Reversal Film etc.
• Capture format: pixel count, digital file type (RAW, TIFF, JPEG), film format (135 film, 120 film, 5x4, 10x8).
• Processing: digital and / or chemical processing of 'negative' and 'print'.

Pixel counts

The number of pixels n for a given maximum resolution (w horizontal pixels by h vertical pixels) is the product n = w × h. This yields e. g. 1.92 megapixels (1,920,000 pixels) for an image of 1600 × 1200. The majority of compact (not SLR) digital cameras have a 4:3 aspect ratio, i.e. w/h = 4/3. ^[1]. According to Digital Photography Review, the 4:3 ratio is because "computer monitors are 4:3 ratio, old CCD's always had a 4:3 ratio, and thus digital cameras inherited this aspect ratio."^[1]

The pixel count quoted by manufacturers can be misleading as it may not be the number of full-colour pixels. For cameras using single-chip image sensors the number claimed is the total number of single-colour-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the Foveon X3 sensor. However, the images will have different numbers of RGB pixels: the Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while the cameras with Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. It is difficult to compare the resolutions based on the megapixel ratings of these two types of sensors, and therefore sometimes subject of dispute.

The pixel count quoted by manufacturers can be misleading as it may not be the number of full-color pixels. For cameras using single-chip image sensors the number claimed is the total number of single-color-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the Foveon X3 sensor. However, the images will have different numbers of RGB pixels: the Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while the cameras with Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. It is difficult to compare the resolutions based on the megapixel ratings of these two types of sensors, and therefore sometimes subject of dispute.

Resolution

Resolution provides an indication of the amount of detail that is captured, but, like the other metrics, resolution is just another factor out of many in determining the quality of an image. Furthermore, different methods of creating an image make it impossible to compare the resolutions of cameras simply based on the number of pixels produced by the image sensor. For example, the Sigma SD14 camera uses Foveon technology, which is quite different from most other digital cameras. It claims to be a 14 megapixel camera, but is generally considered to have detail-capturing capabilities roughly equivalent to 9 megapixels in terms of Bayer sensors. 

The relative increase in detail resulting from an increase in resolution is better compared by looking at the number of pixels across (or down) the picture, rather than the total number of pixels in the picture area. For example, a sensor of 2560 × 1600 sensor elements is described as "4 megapixels" (2560 × 1600 = 4,096,000). Increasing to 3200 × 2048 increases the pixels in the picture to 6,553,600 (6.5 megapixels), a factor of 1.6, but the pixels per cm in the picture (at the same image size) increases by only 1.25 times. A measure of the comparative increase in linear resolution is the square root of the increase in area resolution, i.e., megapixels in the entire image.