JPEG lossless

[wanglon...@163.com]

hello all：
Recently，I decode a DICOM file whose transfer syntax is
1.2.840.1008.1.2.4.57，Bits allocated=16，Bits stored=12，bits high=11，
pixel representation=1。I know how to get the Huffman table and get the
data from the bits stream。However，I have a problem ：what does the data
mean？do I need to remove high bits ? the data is the pixel data that
every byte mean pixel data ? Can anyone give me some advices ? Thank
you very much !

[Marco Eichelberg]

Dear anonymous,

After decompression, the sequence of bytes comprising the content of
(7fe0,0010) Pixel Data needs to interpreted just as if the data had
been read from an uncompressed DICOM file in default transfer syntax,
i.e. you indeed need to mask bits 12-15 of each 16-bit-field
(which must be interpreted as being in little endian byte order)
with the sign bit, i.e. replicate bit 11 in the higher order bits
if you want a correctly interpretable signed short integer
(and your underlying CPU architecture uses two's complement to
represent signed).

Best regards,
Marco Eichelberg