Raw image format
Normally, the image is processed by a raw converter, in a wide-gamut internal color space where precise adjustments can be made before conversion to a viewable file format such as JPEG or PNG for storage, printing, or further manipulation.
Unlike physical film after development, the Raw file preserves the information captured at the time of exposure.
The purpose of raw image formats is to save, with minimum loss of information, data obtained from the sensor.
[3] Most raw image file formats store information sensed according to the geometry of the sensor's individual photo-receptive elements (sometimes called pixels) rather than points in the expected final image: sensors with hexagonal element displacement, for example, record information for each of their hexagonally-displaced cells, which a decoding software will eventually transform into the rectangular geometry during "digital developing".
Raw files contain the information required to produce a viewable image from the camera's sensor data.
Raw files thus contain the full dynamic range (typically 12- or 14-bit) data as read out from each of the camera's image sensor pixels.
Flatbed and film scanner sensors are typically straight narrow RGB or RGBI (where "I" stands for the additional infrared channel for automatic dust removal) strips that are swept across an image.
The raw data are processed very rapidly inside the scanner to select out the best part of the available dynamic range so only the result is passed to the computer for permanent storage, reducing the amount of data transferred and therefore the bandwidth requirement for any given speed of image throughput.
[12] Phase One's raw converter Capture One also offers corrections for geometrical distortion, chromatic aberration, purple fringing and keystone correction emulating the shift capability of tilt-shift in software and specially designed hardware, on most raw files from over 100 different cameras.
To obtain an image from a raw file, this mosaic of data must be converted into standard RGB form.
Several major camera manufacturers, including Nikon, Canon and Sony, encrypt portions of the file in an attempt to prevent third-party tools from accessing them.
The availability of high-quality open source software which decodes raw image formats, particularly dcraw, has helped to alleviate these concerns.
[28] Makers of "niche" cameras who might otherwise have difficulty getting support from software companies frequently use DNG as their native raw image format.
[15] To be viewed or printed, the output from a camera's image sensor has to be processed, that is, converted to a photographic rendering of the scene, and then stored in a standard raster graphics format such as JPEG.
[citation needed] Nearly all digital cameras can process the image from the sensor into a JPEG file using settings for white balance, color saturation, contrast, and sharpness that are either selected automatically or entered by the photographer before taking the picture.
In January 2005, Apple released iPhoto 5, which offered basic support for viewing and editing many raw file formats.
[49] As of October 2016, Microsoft had not released an updated version since April 2014, which supported some specific cameras by the following manufacturers: Canon, Casio, Epson, Fujifilm, Kodak, Konica Minolta, Leica, Nikon, Olympus, Panasonic, Pentax, Samsung, and Sony.
[53][54] Android Lollipop 5.0, introduced in late 2014, can allow smartphones to take 10-bit and 16-bit raw images, useful in low-light situations.
For example, "Photoshop Raw" files (.raw) contain a pure array of bytes top-to-bottom, left-to-right pixel order.
Especially in photography and graphic design, where color management and extended gamuts are important, and large images are common.
