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    Method for image compression, related system and computer product therefor
    1.
    发明公开
    Method for image compression, related system and computer product therefor 有权
    系统与Verfahren zur Bildkodierung undzugehörigesRechnerprogrammprodukt

    公开(公告)号：EP1632902A1

    公开(公告)日：2006-03-08

    申请号：EP04020969.4

    申请日：2004-09-03

    Applicant: STMicroelectronics S.r.l. ,  STMicroelectronics Limited

    Inventor： Smith, Stewart G. ,  Bruna, Arcangelo Ranieri ,  Vella, Filippo

    IPC: G06T9/00

    CPC classification number: H04N19/192 ,  H04N19/115 ,  H04N19/124 ,  H04N19/146 ,  H04N19/15 ,  H04N19/182

    Abstract: A method for image compression of a set of image data (I) includes operating a quantization operation (20; 150; 230) on the image data (I), said quantization operation (20; 150; 230) including controlling a compression factor by applying a scaled quantization level ( ), obtained by multiplying a first quantization level (Q) by a gain factor (G; Gs; Gi), the gain factor (G; Gs; Gi) being updated (100; 1000; 110; 300) as a function of a bit per pixel value (bpp) of a compressed image (O). The update operation (1000; 110; 300) includes an iterative procedure (110) comprising at least one iteration step (Eq. 6; Eq. 7) that provides for updating a current gain factor (G n+1 ) as a function of a previous gain (G n ) used for performing a previous compression step and as a function of a ratio (G n ) of the bit per pixel value (bpp) of the compressed image (O) at the previous compression step to a target bit per pixel value (T).
    Preferred application is in Joint Photographic Experts Group (JPEG) and digital still cameras.

    Abstract translation: 一组图像数据（I）的图像压缩方法包括对图像数据（I）进行量化操作（20; 150; 230），所述量化操作（20; 150; 230）包括通过 通过将第一量化级别（Q）乘以增益因子（G; Gs; Gi），被更新的增益因子（G; Gs; Gi）获得的缩放量化电平（）（100; 1000; 110; 300 ）作为压缩图像（O）的像素值（bpp）的位的函数。 更新操作（1000; 110; 300）包括迭代过程（110），该迭代过程包括至少一个迭代步骤（等式6;等式7），该迭代步骤用于更新当前增益因子（G n + 1） 用于执行先前压缩步骤的先前增益（G n）和作为先前压缩步骤的压缩图像（O）的比特每像素值（bpp）的比率（G n）的函数的目标比特 每像素值（T）。 联合图像专家组（JPEG）和数码相机的首选应用。

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