Method of and apparatus for compressing image representing signals

Claim 2

A data compression apparatus comprising: first processing means for subjecting input image data included in a signal inputted to the apparatus to a predetermined horizontal-direction filtering process and outputting a first filtered signal including horizontally filtered data therein; second processing means for subjecting the input image data to a predetermined vertical-direction filtering process and outputting a second filtered signal including vertically filtered data therein; calculating means for executing a predetermined calculation on the horizontally filtered data and the vertically filtered data in the first and second filtered signals outputted from said first and second processing means, and outputting a signal including calculated data therein representative of the predetermined calculation, wherein the predetermined calculation includes at least an addition; predicted-amount generating means for converting the calculated data in the signal outputted from the calculating means into a corresponding predicted code amount, and outputting a prediction signal including the predicted code amount therein; setting means for setting a target code amount and generating a target signal representative thereof; limit-value generating means for deriving a difference between the predicted code amount in the prediction signal and the target code amount represented by the target signal, and outputting a limiting signal including therein a horizontal-direction band limiting value and a vertical-direction band limiting value corresponding to the derived difference; horizontal limiting means for limiting a horizontal-direction band of the input image data in accordance with the horizontal-direction band limiting value in the limiting signal outputted from the limit-value generating means; and vertical limiting means for limiting a vertical-direction band of the input image data in accordance with the vertical-direction band limiting value in the limiting signal outputted from the limit-value generating means.

Claim 3

A data compression apparatus comprising: first processing means for subjecting input image data included in a signal inputted to the apparatus to a predetermined horizontal-direction filtering process having at least two different filtering characteristics, and outputting a first filtered signal including horizontally filtered data therein; second processing means for subjecting the input image data to a predetermined vertical-direction filtering process having at least two different filtering characteristics, and outputting a second filtered signal including vertically filtered data therein; first calculating means for calculating a horizontal-direction activity value from the horizontally filtered data in the first filtered signal outputted from the first processing means, and outputting a horizontal activity signal including the horizontal-direction activity value therein; second calculating means for calculating a vertical-direction activity value from the vertically filtered data in the second filtered signal outputted from the second processing means, and outputting a vertical activity signal including the vertical-direction activity value therein; adding means for adding the horizontal-direction activity value and the vertical-direction activity value respectively calculated by the first and second calculating means, and outputting a signal including addition data therein representing the added values; means for converting the addition data in the signal outputted from the adding means into a corresponding predicted code amount, and outputting a prediction signal including the predicted code amount therein; setting means for setting a target code amount and generating a target signal representative thereof; limit-value generating means for deriving a difference between the predicted code amount in the prediction signal and the target code amount represented by the target signal, and outputting a limiting signal including therein a horizontal-direction band limiting value and a vertical-direction band limiting value corresponding to the derived difference; horizontal limiting means for limiting a horizontal-direction band of the input image data in accordance with the horizontal-direction band limiting value in the limiting signal outputted from the limit-value generating means; and vertical limiting means for limiting a vertical-direction band of the input image data in accordance with the vertical-direction band limiting value in the limiting signal outputted from the limit-value generating means.

Claim 4

A data compression apparatus comprising: first processing means for subjecting input image data included in a signal inputted to the apparatus to a predetermined horizontal-direction filtering process having at least two different filtering characteristics, and outputting a first filtered signal including horizontally filtered data therein; second processing means for subjecting the input image data to a predetermined vertical-direction filtering process having at least two different filtering characteristics, and outputting a second filtered signal including vertically filtered data therein; first calculating means for calculating a horizontal-direction activity value from the horizontally filtered data in the first filtered signal outputted from the first processing means, and outputting a horizontal activity signal including the horizontal-direction activity value therein; second calculating means for calculating a vertical-direction activity value from the vertically filtered data in the second filtered signal outputted from the second processing means, and outputting a vertical activity signal including the vertical-direction activity value therein; adding means for adding the horizontal-direction activity value and the vertical-direction activity value respectively calculated by the first and second calculating means, and outputting a signal including addition data therein representing the added values; means for converting the addition data in the signal outputted from the adding means into a corresponding predicted code amount, and outputting a prediction signal including the predicted code amount therein; setting means for setting a target code amount and generating a target signal representative thereof; limit-value generating means for deriving a difference between the predicted code amount in the prediction signal and the target code amount represented by the target signal, and outputting a limiting signal including therein a horizontal-direction band limiting value and a vertical-direction band limiting value corresponding to the derived difference; horizontal limiting means for limiting a horizontal-direction band of the input image data in accordance with the horizontal-direction band limiting value in the limiting signal outputted from the limit-value generating means; and vertical limiting means for limiting a vertical-direction band of the input image data in accordance with the vertical-direction band limiting value in the limiting signal outputted from the limit-value generating means.