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Light field camera
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Light field camera
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.
One type uses an array of micro-lenses placed in front of an otherwise conventional image sensor to sense intensity, color, and directional information. Multi-camera arrays are another type. A holographic image is a type of film-based light field image.
The first light field camera was proposed by Gabriel Lippmann in 1908. He called his concept "integral photography". Lippmann's experimental results included crude integral photographs made by using a plastic sheet embossed with a regular array of microlenses, or by partially embedding small glass beads, closely packed in a random pattern, into the surface of the photographic emulsion.
In 1992, Adelson and Wang proposed a design that reduced the correspondence problem in stereo matching. To achieve this, an array of microlenses is placed at the focal plane of the camera main lens. The image sensor is positioned slightly behind the microlenses. Using such images, the displacement of image parts that are not in focus can be analyzed and depth information can be extracted.
The "standard plenoptic camera" is a mathematical model used by researchers to compare designs. By definition it has microlenses placed one focal length away from the image plane of a sensor. In 2004, a team at Stanford University Computer Graphics Laboratory used a 16-megapixel camera to demonstrate that pictures can be refocused after they are taken. The system used a 90,000-microlens array, yielding a resolution of 90 kilopixels. Research has shown that its maximum baseline is confined to the main lens entrance pupil size which is small relative to stereoscopic setups. This implies that the "standard plenoptic camera" may be intended for close-range applications as it exhibits increased depth resolution at distances that can be metrically predicted based on the camera's parameters.
Lumsdaine and Georgiev described a design in which the microlens array can be positioned before or behind the focal plane of the main lens. This modification samples the light field in a way that trades angular resolution for higher spatial resolution. With this design, images can be refocused with a much higher spatial resolution than images from a standard plenoptic camera. However, the lower angular resolution can introduce aliasing artifacts.
A design that used a low-cost printed film mask instead of a microlens array was proposed in 2007. This design reduces the chromatic aberrations and loss of boundary pixels seen in microlens arrays, and allows greater spatial resolution. However, the mask-based design reduces the amount of light that reaches the image sensor, reducing brightness.
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Light field camera
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.
One type uses an array of micro-lenses placed in front of an otherwise conventional image sensor to sense intensity, color, and directional information. Multi-camera arrays are another type. A holographic image is a type of film-based light field image.
The first light field camera was proposed by Gabriel Lippmann in 1908. He called his concept "integral photography". Lippmann's experimental results included crude integral photographs made by using a plastic sheet embossed with a regular array of microlenses, or by partially embedding small glass beads, closely packed in a random pattern, into the surface of the photographic emulsion.
In 1992, Adelson and Wang proposed a design that reduced the correspondence problem in stereo matching. To achieve this, an array of microlenses is placed at the focal plane of the camera main lens. The image sensor is positioned slightly behind the microlenses. Using such images, the displacement of image parts that are not in focus can be analyzed and depth information can be extracted.
The "standard plenoptic camera" is a mathematical model used by researchers to compare designs. By definition it has microlenses placed one focal length away from the image plane of a sensor. In 2004, a team at Stanford University Computer Graphics Laboratory used a 16-megapixel camera to demonstrate that pictures can be refocused after they are taken. The system used a 90,000-microlens array, yielding a resolution of 90 kilopixels. Research has shown that its maximum baseline is confined to the main lens entrance pupil size which is small relative to stereoscopic setups. This implies that the "standard plenoptic camera" may be intended for close-range applications as it exhibits increased depth resolution at distances that can be metrically predicted based on the camera's parameters.
Lumsdaine and Georgiev described a design in which the microlens array can be positioned before or behind the focal plane of the main lens. This modification samples the light field in a way that trades angular resolution for higher spatial resolution. With this design, images can be refocused with a much higher spatial resolution than images from a standard plenoptic camera. However, the lower angular resolution can introduce aliasing artifacts.
A design that used a low-cost printed film mask instead of a microlens array was proposed in 2007. This design reduces the chromatic aberrations and loss of boundary pixels seen in microlens arrays, and allows greater spatial resolution. However, the mask-based design reduces the amount of light that reaches the image sensor, reducing brightness.
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