中科微点-全球专利检索

  1. Login
  2. Sign Up

Search Results

44 records (took 0.021 seconds)

    APPARATUS AND METHOD OF ATTENUATING DISTORTION INTRODUCED BY A PREDICTIVE CODING IMAGE COMPRESSOR
    29.
    发明专利
    APPARATUS AND METHOD OF ATTENUATING DISTORTION INTRODUCED BY A PREDICTIVE CODING IMAGE COMPRESSOR 未知

    公开(公告)号：CA1325672C

    公开(公告)日：1993-12-28

    申请号：CA562726

    申请日：1988-03-28

    Applicant: IBM

    Inventor： GONZALES CESAR A ,  PENNEBAKER WILLIAM B

    IPC: H04N7/32 ,  G06T9/00 ,  H03M7/30 ,  H04N7/26 ,  H04N19/593 ,  H04N7/137

    Abstract: APPARATUS AND METHOD OF ATTENUATING DISTORTION INTRODUCED BY PREDICTIVE CODING IMAGE COMPRESSION The present invention relates to a predictive coding method and related apparatus which (a) computes a value D representing the difference between an original graylevel value for a current pixel and a predicted value for the current pixel; (b) associates each successive range of D values to a respective quantization level, each quantization level QN having a respective QN value representing the range corresponding thereto; (c) sets a respective QERR value to D for the current pixel, when the QN value is zero; (d) re-maps m QERR values to n (n ? m) MERR values; (e) assigns to the value MERR=0 those QERR values in which ¦QERR¦?(+Q1VALUE)/2 sums the MERR values for successive pixels in a QN=Q0 region; and (f) adjusts the QN value from the value of Q0 by the value of Q1 for a pixel at which the summed value reaches a predefined threshold. QN values, adjusted as appropriate, are subjected to entropy coding compression and decompression. In the decompression process, pixel values are reconstructed. According to the invention, the reconstructed values are subjected to a vertical filter in which a pixel having a reconstructed value I0 is filtered to have a value I'0=I0+¢(I-1-I0)C-+(I+1-I0)C+! wherein C+ and C- are respective predefined clamping values, and wherein I-1 and I+1 are the respective reconstructed values of pixels adjacently below and adjacently above the current pixel.

    METHOD FOR CONVERTING A BIT MAP OF AN IMAGE TO A RUN LENGTH OR RUN END REPRESENTATION
    30.
    发明专利
    METHOD FOR CONVERTING A BIT MAP OF AN IMAGE TO A RUN LENGTH OR RUN END REPRESENTATION 未知

    公开(公告)号：CA1304812C

    公开(公告)日：1992-07-07

    申请号：CA478625

    申请日：1985-04-09

    Applicant: IBM

    Inventor： ANDERSON KAREN L ,  MITCHELL JOAN L V ,  PENNEBAKER WILLIAM B ,  GOERTZEL GERALD

    IPC: G06F3/153 ,  G06T9/00 ,  H03M7/46 ,  H04N1/41 ,  H04N1/419 ,  H04N7/12

    Abstract: A method for converting an image from a bit map to a run end or run length representation includes the steps of : storing the image as a bit map representation; accessing for each byte in an image by a look-up table a selected routine, corresponding to such byte, from a number of routines for converting bit strings to run representations, wherein the look-up table accessed is selected in accordance with a color value of a preceding pixel binary bit; and executing the selected routine on the current byte to convert the bit string to a run representation; storing in a run representation buffer, as a count value, each run representation; repeating the above steps of accessing and executing for each byte and storing for each run of continuous color to the end of the image. Y0984-032

Patent Agency Ranking