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Exchangeable Image File Format
Exchangeable image file format (officially Exif, according to JEIDA/JEITA/CIPA specifications) is a standard that specifies formats for images, sound, and ancillary tags used by digital cameras (including smartphones), scanners and other systems handling image and sound files recorded by digital cameras. The specification uses the following existing encoding formats with the addition of specific metadata tags: JPEG lossy coding for compressed image files, TIFF Rev. 6.0 ( RGB or YCbCr) for uncompressed image files, and RIFF WAV for audio files (linear PCM or ITU-T G.711 μ-law PCM for uncompressed audio data, and Interactive Multimedia Association, IMA-ADPCM for compressed audio data). It does not support JPEG 2000 or GIF encoded images. This standard consists of the Exif image file specification and the Exif audio file specification. Background Exif is supported by almost all camera manufacturers. The metadata tags defined in the Exif standard cover a broad spectrum: * Cam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wikimedia Commons
Wikimedia Commons (or simply Commons) is a media repository of free-to-use images, sounds, videos and other media. It is a project of the Wikimedia Foundation. Files from Wikimedia Commons can be used across all of the Wikimedia projects in all languages, including Wikipedia, Wikivoyage, Wikisource, Wikiquote, Wiktionary, Wikinews, Wikibooks, and Wikispecies, or downloaded for offsite use. As of July 2022, the repository contains over 87 million free-to-use media files, managed and editable by registered volunteers.commons:Special:Statistics, Statistics page on Wikimedia Commons History The idea for the project came from Erik Möller in March 2004 and Wikimedia Commons were launched in September 7, 2004. In July 2013, the number of edits on Commons reached 100,000,000. Since 2018 it became possible to upload 3D models to the site. One of the first models uploaded to Commons was a reconstruction of the Asad Al-Lat statue which was destroyed in Palmyra by the Islamic State, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resource Interchange File Format
The Resource Interchange File Format (RIFF) is a generic file container format for storing data in tagged chunks. It is primarily used to store multimedia such as sound and video, though it may also be used to store any arbitrary data. The Microsoft implementation is mostly known through container formats like AVI, ANI and WAV, which use RIFF as their basis. History RIFF was introduced in 1991 by Microsoft and IBM, and was presented by Microsoft as the default format for Windows 3.1 multimedia files. It is based on Electronic Arts' Interchange File Format, introduced in 1985 on the Commodore Amiga, the only difference being that multi-byte integers are in little-endian format, native to the 80x86 processor series used in IBM PCs, rather than the big-endian format native to the 68k processor series used in Amiga and Apple Macintosh computers, where IFF files were heavily used. A RIFX format, which is big-endian, was also introduced. In 2010 Google introduced the WebP pic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPTC Information Interchange Model
The Information Interchange Model (IIM) is a file structure and set of metadata attributes that can be applied to text, images and other media types. It was developed in the early 1990s by the International Press Telecommunications Council (IPTC) to expedite the international exchange of news among newspapers and news agencies. The full IIM specification includes a complex data structure and a set of metadata definitions. Although IIM was intended for use with all types of news items — including simple text articles — a subset found broad worldwide acceptance as the standard embedded metadata used by news and commercial photographers. Information such as the name of the photographer, copyright information and the caption or other description can be embedded either manually or automatically. IIM metadata embedded in images are often referred to as "IPTC headers", and can be easily encoded and decoded by most popular photo editing software. The Extensible Metadata Pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tag Image File Format / Electronic Photography
Tag Image File Format/Electronic Photography (TIFF/EP) is a digital image file format standard – ISO 12234-2, titled "Electronic still-picture imaging – Removable memory – Part 2: TIFF/EP image data format". This is different from the Tagged Image File Format, which is a standard administered by Adobe currently called "TIFF, Revision 6.0 Final – June 3, 1992". The TIFF/EP standard is based on a subset of the Adobe TIFF standard, and a subset of the JEITA Exif standard, with some differences and extensions. One of the uses of TIFF/EP is as a raw image format. A characteristic of most digital cameras (but excluding those using the Foveon X3 sensor or similar, hence especially Sigma cameras) is that they use a color filter array (CFA). Software processing a raw image format for such a camera needs information about the configuration of the color filter array, so that the raw image can identify separate data from the individual sites of the sensor. Ideally this infor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adobe RGB
The Adobe RGB (1998) color space or opRGB is a color space developed by Adobe Systems, Inc. in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as a computer display. The Adobe RGB (1998) color space encompasses roughly 50% of the visible colors specified by the CIELAB color space – improving upon the gamut of the sRGB color space, primarily in cyan-green hues. It was subsequently standardized by the IEC as IEC 61966-2-5:1999 with a name opRGB (optional RGB color space) and is used in HDMI. Historical background Beginning in 1997, Adobe Systems was looking into creating ICC profiles that its consumers could use in conjunction with Photoshop's new color management features. Since not many applications at the time had any ICC color management, most operating systems did not ship with useful profiles. Lead developer of Photoshop, Thomas Knoll decided to build an ICC profile around s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thumbnail
Thumbnails are reduced-size versions of pictures or videos, used to help in recognizing and organizing them, serving the same role for images as a normal text index does for words. In the age of digital images, visual search engines and image-organizing programs normally use thumbnails, as do most modern operating systems or desktop environments, such as Microsoft Windows, macOS, KDE (Linux) and GNOME (Linux). On web pages, they also avoid the need to download larger files unnecessarily. Implementation Thumbnails are ideally implemented on web pages as separate, smaller copies of the original image, in part because one purpose of a thumbnail image on a web page is to reduce bandwidth and download time. Some web designers produce thumbnails with HTML or client-side scripting that makes the user's browser shrink the picture, rather than use a smaller copy of the image. This results in no saved bandwidth, and the visual quality of browser resizing is usually less than id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO Speed
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras. Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a ''slow film''. Highly sensitive films are correspondingly termed ''fast films''. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grain or higher image noise of other types). In short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the quantum efficiency of the film or sensor. Film speed measurement systems Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metering Mode
In photography, the metering mode refers to the way in which a camera determines exposure. Cameras generally allow the user to select between ''spot'', ''center-weighted average'', or ''multi-zone'' metering modes. The different metering modes allow the user to select the most appropriate one for use in a variety of lighting conditions. In complex light situations professional photographers tend to switch to manual mode, rather than depending on a setting determined by the camera. Examples of metering modes Spot metering With spot metering, the camera will measure only a very small area of the scene (1–5% of the viewfinder area). By default this is the centre of the scene. The user can select a different off-centre spot or recompose by moving the camera after metering. Certain models support a mode which allows averaging of multiple spot meter readings, and some support metering of highlight and shadow areas. Spot metering is not influenced by other areas in the frame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Length
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of a thin lens in air, a positive focal length is the distance over which initially collimated (parallel) rays are brought to a focus, or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power. In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shutter Speed
In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter is open) when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. of a second will let half as much light in as . Introduction The camera's shutter speed, the lens's aperture or f-stop, and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure). Exposure value (EV) is a quantity that accounts for the shutter speed and the f-number. Once the sensitivity to light of the recording surface (either film or sensor) is set in numbers expressed in " ISOs" (ex: 200 ISO, 400 ISO), the light emitted by the scene photographed can be controlled through aperture and shutter-speed to match the film or sensor sensitivity to light. This will achieve a good exposure when all the details of the sce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An optical system typically has many openings or structures that limit the ray bundles (ray bundles are also known as ''pencils'' of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that primarily determines the ray cone angle and brightness at the image point. In some contexts, especially in photography and astronomy, ''aperture'' refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope, the apertu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JPEG 2000
JPEG 2000 (JP2) is an image compression standard and coding system. It was developed from 1997 to 2000 by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi (later the JPEG president), with the intention of superseding their original JPEG standard (created in 1992), which is based on a discrete cosine transform (DCT), with a newly designed, wavelet-based method. The standardized filename extension is .jp2 for ISO/IEC 15444-1 conforming files and .jpx for the extended part-2 specifications, published as ISO/IEC 15444-2. The registered MIME types are defined in RFC 3745. For ISO/IEC 15444-1 it is image/jp2. JPEG 2000 code streams are regions of interest that offer several mechanisms to support spatial random access or region of interest access at varying degrees of granularity. It is possible to store different parts of the same picture using different quality. JPEG 2000 is a compression standard based on a discrete wavelet transform (DWT). The standar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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