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Showing papers on "Channel (digital image) published in 1972"


Patent
13 Sep 1972
TL;DR: A channel plate with color selection electrodes and color phosphors was used as an image display screen in a color television tube as mentioned in this paper, where the color selection electrode was replaced by a color selector.
Abstract: A channel plate with color selection electrodes and color phosphors for use as an image display screen in a color television tube.

9 citations


Patent
01 Nov 1972
TL;DR: In this paper, a pair of color demodulators demodulate along wide angle axes of reduced included angle in the flesh tone region, and a third demodulator generates a proportional correction signal which is subtracted from a demodulated B-Y color difference signal to correct for errors in the green and cyan regions caused by wide angle demodulation.
Abstract: In the chroma channel of a color television receiver, a pair of color demodulators demodulate along wide angle axes of reduced included angle in the flesh tone region. A third demodulator, in response to the presence of green and cyan hues in a chroma signal, generates a proportional correction signal which is subtracted from a demodulated B-Y color difference signal to correct for errors in the green and cyan regions caused by wide angle demodulation.

6 citations


Book ChapterDOI
TL;DR: In this article, an inverting electrostatic lens is used to focus the electron image from the primary photocathode to the input of the channel plate, and proximity focusing between the output and the fluorescent screen.
Abstract: Publisher Summary This chapter discusses some design aspects of a small high-contrast channel image intensifier. This channel image intensifier uses an inverting electrostatic lens to focus the electron image from the primary photocathode to the input of the channel plate, and proximity focusing between the channel plate output and the fluorescent screen. The major electron optical-design problem occurs in the inverting section in meeting the principal design requirements of: (1) a flat image plane to match the planar channel-plate input; (2) a resolution performance such that the major effect on the overall modulation transfer is that of the proximity-focused channel plate to screen section, and (3) a diode construction to obviate the need for preset stabilized focusing voltages. The operating voltages required for the tube are 5 kV between the photocathode and input to the channel plate, and a further 5 kV between the channel-plate output and the fluorescent screen. Results demonstrate that a small, high-contrast image intensifier can be manufactured using the channel multiplication principle, which has a performance equal to or better than other types of intensifiers at all but extremely low light levels.

5 citations


Book ChapterDOI
TL;DR: In this paper, the authors investigated the possibility of making a proximity focused X-ray intensifier using a channel plate to provide the gain, which can be viewed directly without the need of auxiliary viewing systems.
Abstract: Publisher Summary This chapter provides an overview of channel electron-multiplier plates in X-ray image intensification. Channel electron-multiplier plates have provided the means of achieving a very high electron gain in a small volume and would thus appear to be ideal for use in image intensifiers. The conventional type of X-ray image intensifier, which needs to have a large diameter to cover areas of interest in the human body, achieves its gain by electron optically demagnifying the image and accelerating the electrons by means of a potential difference of about 25 kV. This study investigates the possibility of making a proximity focused X-ray intensifier using a channel plate to provide the gain. This tube has a magnification of unity and can be viewed directly without the need of auxiliary viewing systems. The size of the tube is limited to 5" for ease of manufacture in the research laboratory although there is no fundamental limitation to the size. This chapter describes the manufacture and properties of the channel plates used, and then discusses the construction of the tube and the performance requirements. The results of measurements on some tubes are given, together with some photographs of the images produced.

4 citations


Patent
A Larsen1
19 May 1972
TL;DR: In this article, a camera spectral sensitivity characteristic having both the positive and negative lobes is combined to form a single striped optical spatial filter at the camera, and the resultant composite video signal is demodulated to yield a chrominance output signal proportional to the difference between the light transmission provided by the filter stripes so that the prescribed spectral sensitivity characteristics is produced for each output channel.
Abstract: Improved color reproduction is made possible by a television camera exhibiting a complete predetermined camera spectral sensitivity characteristic having both the positive and negative lobes. Materials having transmission characteristics which are responsive to both the positive and inverted negative lobes of the predetermined characteristics are combined to form a single striped optical spatial filter at the camera, and the resultant composite video signal is demodulated to yield a chrominance output signal proportional to the difference between the light transmission provided by the filter stripes so that the prescribed spectral sensitivity characteristic is produced for each output channel. The technique permits a camera to exhibit complete spectral characteristics and to generate by direct optical means any color signal, including I or Q, and it is applicable to single or multiple tube cameras using spatial modulation techniques for color discrimination.

4 citations


Patent
25 Jul 1972
TL;DR: In this paper, the optical division ratio is changed from 25:75-50:50 between luminance channel Y and chrominance channel C for the isolating luminance system color TC camera which uses two units of the solid state pickup element.
Abstract: PURPOSE:To increase greatly the sensitivity by means of the solid state pickup device, by using the high-resolution puckup element for the luminance channel and then the element featuring the low resolution and high sensitivity for the chrominance channel each. CONSTITUTION:If the optical division ratio is changed from 25:75-50:50 between luminance channel Y and chrominance channel C for the isolating luminance system color TC camera which uses two units of the solid state pickup element, the double sensitivity is obtained in terms of channel Y. On the other hand, the optical division ratio must be set triple or more to secure the double sensitivity for channel C. In this connection, the scanning of channel C is carried out with every second scanning line. In other words, the scanning is carried out as I-1, I-2... in the 1st field II-1, II-2... in the 2nd field, III-1, III-2... in the 3rd field, and IV-1, IV-2... in the 4th field respective ly. In this case, the vertical resolution becomes 1/2, and the sensitivity becomes about double since the storage time features the double value. And no problem is caused in pratical use because the lowering of the resolution is limited to channel C.

2 citations


Journal ArticleDOI
TL;DR: It has been found that if the tristimulus values of a color are transmitted over the channel, the effects of channel errors are to desaturate ali colors toward a mid-gray and shift the hue of transmitted colors toward cyan, magenta, or yellow.
Abstract: This paper considers the effects of channel errors on the digital transmission of color images. In the transmission system analyzed, each picture element of a color image is represented by three color components. Two cases are considered: the tristimulus representation and the luminance and chromaticity representation. Each color component is coded with a constant-word-length PCM code and passed through a binary symmetric channel. Channel errors are related to chromaticity and luminance errors in a reconstructed image by the use of color space diagrams. Statistical characteristics of image errors are determined for various color representations. It has been found that if the tristimulus values of a color are transmitted over the channel, the effects of channel errors are to desaturate ali colors toward a mid-gray. For luminance/chromaticity representations, channel errors tend to shift the hue of transmitted colors toward cyan, magenta, or yellow.

2 citations


Patent
21 Mar 1972
TL;DR: In this article, a rigid film channel is defined outside the film gate region between the camera body and the cassette, and a film guide is provided on the body of the camera.
Abstract: A film guide is provided on the camera body. Film path means are provided on the cassette. A rigid film channel is defined outside the film gate region between the camera body and the cassette.

2 citations


Book ChapterDOI
TL;DR: In this paper, the authors describe the modulation transfer function (MTF) measurements on channel image intensifiers and suggest to use the normal subjective criteria of image quality assessment to supplement the results of linear analysis.
Abstract: Publisher Summary This chapter describes the modulation transfer function (MTF) measurements on channel image intensifiers. The MTF has been increasingly regarded as one of the most important ways of describing image quality. The application of the MTF to a particular type of imaging device is considered and some pitfalls that must be avoided if meaningful measurements are to be obtained are pointed out. If transfer functions are to be applicable to an image transfer process, the necessary conditions for Fourier transformation must be satisfied. The process must be linear in response and spatially stationary. The channel plate consists of a large number of electron multiplier tubes in a hexagonal array. If the pattern that is imaged through the device is limited to low spatial frequencies, the imaging process can be regarded as being stationary over the restricted spatial frequency range involved. The profile of the line-spread function is measured with a scanning microphotometer. The chapter suggests to use the normal subjective criteria of image-quality assessment to supplement the results of linear analysis.

1 citations


Book ChapterDOI
TL;DR: In this paper, the performance of a low light-level television system can be characterized with the aid of acuity curves, which indicate the size of the smallest object detectable with the system for a given contrast in the scene, as a function of the illumination level.
Abstract: Publisher Summary This chapter discusses the application of channel image intensifiers to low light-level television. The performance of a low light-level television system can in general be characterized with the aid of acuity curves, which indicate the size of the smallest object detectable with the system for a given contrast in the scene, as a function of the illumination level. As in the case of image intensifiers for direct viewing, the two factors of photon noise and modulation transfer normally limit the maximum resolution of the camera chain for stationary objects. In television systems, however, two important additional problems can be created by the translation of the optical image into a video signal by means of a scanning electron beam. The number of bars that can just be resolved per picture width on the photosensitive surface of the camera tube can be related to the signal-to-noise ratio in the video signal. Any reduction in picture resolution, due to the decrease in modulation depth per amplification stage, will be accompanied by a corresponding reduction in the perceptibility of that part of the noise, which was present before the amplification. It is found that the measured square-wave response agreed well with that computed from the component parts.