公开(公告)号：DE602004019275D1

公开(公告)日：2009-03-19

申请号：DE602004019275

申请日：2004-06-07

Applicant: ST MICROELECTRONICS SRL

Inventor： VELLA FILIPPO ,  BRUNA ARCANGELO RANIERI ,  BUEMI ANTONIO VINCENZO

IPC: G06T9/00 ,  H04N7/26 ,  H04N7/36 ,  H04N19/593 ,  H04N19/94

Abstract: A particularly efficient and simple method for Bayer color filter array (CFA) compression requires practically negligible computational complexity and external memory requirement while yielding a substantially lossless performance of the compression-decompression processes.For each color channel, the process comprises the step ofgathering Bayer pattern pixel values by pairs, each pair being composed by two successive pixels belonging to the channel along the scanning direction of the pixels of the image, thus each pair of values representing a current input vector;calculating a predictor vector of the input vector in terms of the differences between the values defining the input vector and a pair of prediction values generated according to a certain criterion, for representing a prediction error;quantizing each so calculated predictor vector according to a heavier or lighter degree of quantization depending on whether the predictor vector is representative of an area of relatively uniform color of the image or of an area of relatively abrupt changes of colors of the image;generating a multibit code representative of the quantized predictor vector of the input vector according to a certain compression ratio.

公开(公告)号：ITTO20021072A1

公开(公告)日：2004-06-11

申请号：ITTO20021072

申请日：2002-12-10

Applicant: ST MICROELECTRONICS SRL

Inventor： BATTIATO SEBASTIANO ,  CASTORINA ALFIO ,  GUARNERA MIRKO ,  VELLA FILIPPO

IPC: G03B20060101 ,  H04N5/232 ,  H04N9/73

公开(公告)号：DE602004010509D1

公开(公告)日：2008-01-17

申请号：DE602004010509

申请日：2004-09-03

Applicant: ST MICROELECTRONICS SRL ,  SGS THOMSON MICROELECTRONICS

Inventor： SMITH STEWART G ,  BRUNA ARCANGELO RANIERI ,  VELLA FILIPPO

IPC: G06T9/00

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.