Font recall system for selective insertion as a caption into a video image

Claim 2

A font recall system comprising: an image store (22) storing a plurality of characters in high dynamic resolution digital sampled data form; a size reducer (46) coupled to receive character defining data from the data store and in response thereto output display character defining data defining characters of a selected size; a caption frame store (32) coupled to receive the output display character defining data and store the received data at address locations therein causing characters defined by the received data to be displayed at selected locations within a video image to form a caption; a video data source (30 or 34) providing data defining a background video image; and a keyer (52) coupled to receive the background video image defining data and the display character defining data from the caption frame store and output in response thereto captioned image data defining the background video image with the caption superimposed thereon.

Claim 3

A font recall system according to Claim 1 above, wherein the caption frame store includes a write inhibit circuit (42) coupled to detect the receipt of noncharacter data and inhibit the writing of noncharacter data into the caption frame store.

Claim 4

A font recall system according to claim 2 above, wherein character data has a value less than or equal to a given magnitude and the inhibit circuit is operative to inhibit the writing of data having a value greater than the given magnitude.

Claim 5

A font recall system according to claim 3 above, wherein the given magnitude corresponds to a white background level.

Claim 6

A font recall system according to any of claims 1 to 4, wherein the keyer is operative to receive and store data defining a selected display character color and generate the captioned image data by mixing the background image defining data and the display character color defining data in proportions dependent on the display-character defining data.

Claim 7

A font recall system according to claim 5 above, wherein in a range of display-character defining data between a predetermined relatively low value and a predetermined relatively high value the background image defining data and the display character color defining data are mixed in the proportions a to (1-a), where a increases from zero to unity in said range.

Claim 8

A font recall system accordingto any foregoing claim, wherein the plurality of characters stored by the image store are each stored as a subframe of video data having a size less than a standard frame of television data.

Claim 9

A font recall system according to any foregoing claim, wherein the plurality of characters stored by the image store are each stored as a subframe of video data having a size of the order of 100 pixels wide by 100 lines high.

Claim 10

A font recall system according to any foregoing claim, wherein the high dynamic resolution digital sampled data form comprises at least six bits of dynamic luminance resolution for each sample data point of a restored character.

Claim 11

A font recall system according to any foregoing claim, wherein the high dynamic resolution digital sampled data form comprises at least eight bits of dynamic luminance resolution for each sample data point of restored character.

Claim 12

A font recall system according to any foregoing claim, wherein each character stored by the image store is stored with a video data frequency less than half the sample data frequency to inhibit the appearance of jagged edge aliasing at character boundaries when the character is displayed.

Claim 13

A font recall system according to any foregoing claim, wherein the video data defining each character stored by the image store is low pass filtered prior to storage to inhibit the appearance of jagged edge aliasing of characters defined by captioned image data output by the keyer.

Claim 14

A font recall system according to any foregoing claim, further comprising a central processing unit and a user console coupled to communicate user commands to the central processing unit, the central processing unit being coupled to control font recall system devices to produce captioned images as commanded by a user through the user console.

Claim 15

A font recall system according to claim 13 above, further comprising a video monitor coupled to receive the captioned image data and display the background video image with the caption superimposed thereon defined by the captioned image feeder.

Claim 16

A font recall system comprising: an image store (22) storing video data defining a font of high dynamic resolution low pass filtered characters; a size reducer (46) coupled to receive from the image store video data defining a selected character and convert said received video data to a character size less than or equal to the original character size; a caption frame store (32) coupled to receive from the size reducer converted video data defining at least one character and to selectively store the converted data in caption frame store storage locations selected to produce a particular caption image; a background frame store (34) coupled to receive and store video data defining a video image frame; a first switch (50) coupled to receive and selectively output video image defining video data either from the background frame store or from a video input (30); a keyer (52) coupled to receive and mix video data from the caption frame store defining a caption image and video data from the first switch defining a background image to produce video output data defining a captioned background image; and an output digital-to-analog converter (54) coupled to receive the output video data and to generate an analog television signal in response thereto.

Claim 17

A font recall system comprising: an image store (22) storing video data defining a font of high dynamic resolution low pass filtered characters; a size reducer (46) coupled to receive from the image store video data defining a selected character and convert said received video data to a character size less than or equal to the original character size; a caption frame store (32) coupled to receive from the size reducer converted video data defining at least one character and to selectively store the converted data in caption frame store storage locations selected to produce a particular caption image; a background frame store (34) coupled to receive and store video data defining a video image frame; a first switch (50) coupled to receive and selectively output video image defining video data either from the background frame store or from a video input (30); a keyer (52) coupled to receive and mix video data from the caption frame store defining a caption image and video data from the first switch defining a background image to produce video output data defining a captioned background image; and an output digital-to-analog converter (54) coupled to receive the output video data and to generate an analog television signal in response thereto.

Claim 18

A font recall system according to claim 15 in which the said video output data from the keyer is written into the said background frame store frame by frame and is read out to the output converter (54) before it is overwritten.