Eastman-kodak Company

Peter L Dillon

Ronald R Firth

Bryce E Bayer

Jerry R Horak

Evan A Edwards

Enrique Garcia

Richard A Spaulding

James J DePalma

Pattern noise in the output signal produced by an array of solid state light responsive elements is reduced by adjusting the responses of a subset of elements towards an average element response, thereby reducing the standard deviation of the element response distribution. The elements receiving response adjustments have responses in the upper and lower extremes of the element response distribution as determined by measuring the output of the sensor under controlled illumination conditions. A pattern noise reducing circuit includes: (1) means for deriving a set of response adjustment signals representing (a) the locations in the array of a subset of elements having responses in the upper and lower extremes of the element response distribution and (b) amounts of adjustment to the responses of said subset of elements to move said element responses toward an average response, and (2) means for applying to the signals representing the imagewise responses of said subset of elements, adjustments corresponding to said response adjustment signals, to produce imagewise output signals having reduced pattern noise. According to a further feature of the invention, redundancy reducing coding (e.g. run length coding) is employed to code the locations of the adjusted elements in the memory, thereby reducing the required size of the memory.

Pattern noise reduction method and apparatus for solid state image

A frame-rate converting film scanner includes means for continuously advancing film at a selected frame rate and for projecting an image of the moving film onto a solid state image sensor for producing a television signal at a standard television field rate. The solid state image sensor includes: (1) a two-dimensional array of image sensing elements having a width equal to the width of the projected image of a film frame and a height equal ot the projected image of 2+X/Y film frames, where X is the projection rate of the film in frames per second and Y is the field rate of the standard video signal in fields per second, (2) a two-dimensional frame storage array, (3) an output register, and (4) a 'drain gate' disposed between the image sensing array and the frame storage array and operable in a first mode to transfer signals from the image sensing array to the storage array and in a second mode to drain signals from the image sensing array. The image of the moving film is projected on the image sensing array to produce an imagewise pattern of photocharge and the sensing array is operated to move the pattern of photocharge accumulated in the array in synchronism with the moving image. As lines of photocharge are advanced to the top of the sensing array, they are dumped by the drain gate. After a predetermined exposure time, a full frame of photocharge is rapidly transferred to the temporary storage array from the image sensing array via the drain gate. The frame of photocharge is read out of the storage array at the standard video field rate via the output register while a new pattern of photocharge is accumulated in the image sensing array. The scanning apparatus includes timing means for keeping track of the location of moving film frames with respect to the image sensing array and clocking means associated with the timing means for rapidly shifting a complete frame's worth of charge into the temporary storage array.

Frame-rate converting film scanner with two-dimensional solid state

A color video signal composed of successive groups of analog color samples, successive samples in at least some of said groups alternating between one color and another, wherein such groups represent successively scanned rows or lines of video frames or fields, is processed, prior to recording, by assigning respective samples to one of a plurality of channels of substantially equal bandwidth in a manner such that respective channels contain subgroups of samples representing only one color per subgroup, thereby minimizing the power at the sampling frequency in such channels. The information in the channels is recorded on a corresponding plurality of tracks on a recording medium by multi-channel essentially-fixed-head recording apparatus thereby realizing the manufacturing economy of essentially-fixed-head type apparatus. In one embodiment of the invention, samples of a first color occur more frequently in the color video signal than do samples of a second color, thereby maximizing the utilization of the information storage capacity of the recording medium. In a preferred implementation, the color video signal is generated by a solid state image sensing array having discrete image sensing elements selectively sensitized to green, red, or blue. Green-sensitive elements occur more frequently in the array than do red- or blue-sensitive elements in recognition of the fact that human visual acuity is higher for green, than for red or blue. The signal is separated sample-by-sample and the samples assigned to eight channels in a manner such that for each group of samples, the samples representing green (green samples) occupy four of the eight channels, and the samples representing red (red samples) and/or blue (blue samples) occupy the other four channels.

Multichannel recording format for a sampled-analog color video signal

Apparatus for correcting time base error (such as flutter, scatter, and skew) in a multichannel, sampled-analog type video signal includes means for clocking the signal portions carried by respective channels into respective deflutter buffers by respective input clock signals derived from horizontal sync information appearing in respective channels. Each buffer contains input register means capable of receiving a signal portion containing flutter distortion, storage means for holding the signal portion received, and output register means for delivering the signal at a substantially constant periodic rate. The input register means is controlled by the input clock signal, which contains flutter distortion corresponding to the flutter distortion in the signal portion. By synchronously delivering the signal portions from the output register means in all of the buffers, under control of a common output clock signal, flutter is removed from the signal portion in each channel, and inherently, scatter and skew among the signal portions in respective channels are removed from the signal.

Apparatus for correcting time base error in a multichannel,

Processing circuitry for discrete-sample-type-color-video signals performs an interpolation along a scan row or line to define intermediate signal levels between signal 'updates' for the individual primary colors. In a preferred implementation, using green, red, and blue as primary colors, green samples occur more frequently than red or blue and interpolated green samples are specially combined to produce a 'slow' green signal that is matched to the frequency ranges of the red and blue signals. The difference between the full green signal and the slow green signal is then used for producing a signal to represent high frequency luminance detail.

Signal processing for discrete-sample-type-color-video signal

Processing circuitry for discrete-sample-type-color-video signals provides signal enhancement by algebraically summing properly weighted delayed, doubly delayed, and undelayed versions of the same signal.

Light responsive elements of a color imaging array are arranged in basic groupings of four aligned elements, which groupings included two luminance-responsive elements that alternate with individual elements for two other basic colors. These groupings are repeated along a line and are shifted by one element in each adjacent line. As a result of intermixing color-responsive elements in this way, high-spatial-frequency luminance sampling is achieved for all directions on the array and closely repeated patterns of elements are achieved for all three basic colors in both fields of the array (here assuming a two-field interlaced readout array). Because closely repeated sampling occurs for all colors in both fields of such an array, the field-to-field color flicker, that can occur when intermixed color sampling is attempted using an interlaced-readout imaging array, is avoided.

Color imaging array

Primary color filters which also pass infrared are employed in cooperation with a broad-spectral-response, image sensing apparatus to provide a color video camera which has an extended range of operation at low light levels. The image beam which reaches the image sensing apparatus is selectively controlled by a regulatable infrared filtering device in cooperation with such primary color filters. Upon detecting a normal light level, the infrared filtering device responds by blocking infrared. At low light levels, on the other hand, infrared blocking is negated and infrared passes through some or all of the primary color filters to augment the faint visible light components which are imaged on the image sensing apparatus.

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Pittsford, NY, United States of America

Peter L Dillon