Computer vision tasks include methods for acquiring, processing, analyzing and understanding digital images, and extraction of high-dimensional data from the real world in order to produce numerical or symbolic information, e.g. in the forms of decisions. Understanding in this context means the transformation of visual images into descriptions of the world that make sense to thought processes and can elicit appropriate action. This image understanding can be seen as the disentangling of symbolic information from image data using models constructed with the aid of geometry, physics, statistics, and learning theory.
The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera.
In photography and videography, multi-exposure HDR capture is a technique that creates high dynamic range (HDR) images by taking and combining multiple exposures of the same subject matter at different exposure levels. Combining multiple images in this way results in an image with a greater dynamic range than what would be possible by taking one single image. The technique can also be used to capture video by taking and combining multiple exposures for each frame of the video. The term "HDR" is used frequently to refer to the process of creating HDR images from multiple exposures. Many smartphones have an automated HDR feature that relies on computational imaging techniques to capture and combine multiple exposures.
Imaging is the representation or reproduction of an object's form; especially a visual representation.
The light field is a vector function that describes the amount of light flowing in every direction through every point in space. The space of all possible light rays is given by the five-dimensional plenoptic function, and the magnitude of each ray is given by its radiance. Michael Faraday was the first to propose that light should be interpreted as a field, much like the magnetic fields on which he had been working. The phrase light field was coined by Andrey Gershun in a classic 1936 paper on the radiometric properties of light in three-dimensional space.
In photography and optics, vignetting is a reduction of an image's brightness or saturation toward the periphery compared to the image center. The word vignette, from the same root as vine, originally referred to a decorative border in a book. Later, the word came to be used for a photographic portrait that is clear at the center and fades off toward the edges. A similar effect is visible in photographs of projected images or videos off a projection screen, resulting in a so-called "hotspot" effect.
A light field camera, also known as a plenoptic camera, is a camera that captures information about the light field emanating from a scene; that is, the intensity of light in a scene, and also the precise direction that the light rays are traveling in space. This contrasts with conventional cameras, which record only light intensity at various wavelengths.
Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing. It is a form of digital imaging based on gathering visible light.
The following are common definitions related to the machine vision field.
In optics and signal processing, wavefront coding refers to the use of a phase modulating element in conjunction with deconvolution to extend the depth of field of a digital imaging system such as a video camera.
The following outline is provided as an overview of and topical guide to photography:
Coded apertures or coded-aperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation. The wavelengths are usually high-energy radiation such as X-rays and gamma rays. A coded "shadow" is cast upon a plane by blocking radiation in a known pattern. The properties of the original radiation sources can then be mathematically reconstructed from this shadow. Coded apertures are used in X- and gamma ray imaging systems, because these high-energy rays cannot be focused with lenses or mirrors that work for visible light.
Focus stacking is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of field (DOF) than any of the individual source images. Focus stacking can be used in any situation where individual images have a very shallow depth of field; macro photography and optical microscopy are two typical examples. Focus stacking can also be useful in landscape photography.
Range imaging is the name for a collection of techniques that are used to produce a 2D image showing the distance to points in a scene from a specific point, normally associated with some type of sensor device.
In computer vision and computer graphics, 3D reconstruction is the process of capturing the shape and appearance of real objects. This process can be accomplished either by active or passive methods. If the model is allowed to change its shape in time, this is referred to as non-rigid or spatio-temporal reconstruction.
Femto-photography is a technique for recording the propagation of ultrashort pulses of light through a scene at a very high speed (up to 1013 frames per second). A femto-photograph is equivalent to an optical impulse response of a scene and has also been denoted by terms such as a light-in-flight recording or transient image. Femto-photography of macroscopic objects was first demonstrated using a holographic process in the 1970s by Nils Abramsson at the Royal Institute of Technology (Sweden). A research team at the MIT Media Lab led by Ramesh Raskar, together with contributors from the Graphics and Imaging Lab at the Universidad de Zaragoza, Spain, more recently achieved a significant increase in image quality using a streak camera synchronized to a pulsed laser and modified to obtain 2D images instead of just a single scanline.
Gradient domain image processing, also called Poisson image editing, is a type of digital image processing that operates directly on the differences between neighboring pixels, rather than on the pixel values. Mathematically, an image gradient represents the derivative of an image, so the goal of gradient domain processing is to construct a new image by integrating the gradient, which requires solving Poisson's equation.
Epsilon photography is a form of computational photography wherein multiple images are captured with slightly varying camera parameters such as aperture, exposure, focus, film speed and viewpoint for the purpose of enhanced post-capture flexibility. The term was coined by Prof. Ramesh Raskar. The technique has been developed as an alternative to light field photography that requires no specialized equipment. Examples of epsilon photography include focal stack photography, High dynamic range (HDR) photography, lucky imaging, multi-image panorama stitching and confocal stereo. The common thread for all the aforementioned imaging techniques is that multiple images are captured in order to produce a composite image of higher quality, such as richer color information, wider-field of view, more accurate depth map, less noise/blur and greater resolution.
Computational imaging is the process of indirectly forming images from measurements using algorithms that rely on a significant amount of computing. In contrast to traditional imaging, computational imaging systems involve a tight integration of the sensing system and the computation in order to form the images of interest. The ubiquitous availability of fast computing platforms, the advances in algorithms and modern sensing hardware is resulting in imaging systems with significantly enhanced capabilities. Computational Imaging systems cover a broad range of applications include computational microscopy, tomographic imaging, MRI, ultrasound imaging, computational photography, Synthetic Aperture Radar (SAR), seismic imaging etc. The integration of the sensing and the computation in computational imaging systems allows for accessing information which was otherwise not possible. For example:
Todor G. Georgiev is a Bulgarian American research scientist and inventor, best known for his work on plenoptic cameras. He is the author of the Healing Brush tool in Adobe Photoshop, and, as of 2020, is a principal scientist at Adobe in San Jose, California. Georgiev's work has been cited 7700 times as of 2020. As an inventor, he has at least 89 patents to his name.
