Picture transmission system using secondary differential variable sampling rate coding

DETAILED DESCRIPTION Accordingly, the principal object of the present invention is to provide a picture transmission system which can improve compression efficiency and remove errors caused in coding, thereby to transmit pictures of good quality.
Briefly stated, the present invention performs prediction on the basis of sampling values obtained by sampling picture data and predictive values by outputting differential values between the sampling values and the predictive values for compression-coding the differential values outputted by the prediction in a variable sampling rate system to transmit the same and expansion-decoding the compression-coded differential values in the variable sampling rate system, thereby to process the values thus decoded as predictors for subsequent sampling points.
Therefore, according to the present invention, compression coding and expansion decoding in the variable sampling rate system are performed within the predictive loop thereby to transmit predictive differential values including errors following compression and expansion in the variable sampling rate coding system, whereby the errors caused in the variable sampling rate coding system are automatically corrected when samples are restored in the receiving area by employing the differential values.
In a preferred embodiment of the present invention, only changed areas in picture data and subsequent picture data are predicted and coded, whereby no transmission is required for unchanged portions, leading to reduction in time for picture transmission.
In another embodiment of the present invention, prediction is successively performed for respective sampling points on one horizontal scanning line (or in the vertical direction) in picture data to store differential values between the respective sampling points and the respective predictors, thereby to successively perform preposition prediction in the vertical direction (or along the horizontal scanning lines) on the basis of the stored differential values and sampling values of the respective sampling points in a subsequent horizontal scanning line portion (or in the vertical direction) so as to perform compression coding of the same on the basis of the differential values obtained by the preposition prediction