J2KPRECINCTSIZE
typedef enum
{
J2KPRECINCTSIZE_FULL = 0,
J2KPRECINCTSIZE_UNIFORM_64 = 1,
J2KPRECINCTSIZE_UNIFORM_128 = 2,
J2KPRECINCTSIZE_UNIFORM_256 = 3,
J2KPRECINCTSIZE_UNIFORM_512 = 4,
J2KPRECINCTSIZE_UNIFORM_1024 = 5,
J2KPRECINCTSIZE_UNIFORM_2048 = 6,
J2KPRECINCTSIZE_HIERARCHICAL1_64 = 7,
J2KPRECINCTSIZE_HIERARCHICAL1_128 = 8,
J2KPRECINCTSIZE_HIERARCHICAL1_256 = 9,
J2KPRECINCTSIZE_HIERARCHICAL1_512 = 10,
J2KPRECINCTSIZE_HIERARCHICAL2_64 = 11,
J2KPRECINCTSIZE_HIERARCHICAL2_128 = 12,
J2KPRECINCTSIZE_HIERARCHICAL2_256 = 13,
J2KPRECINCTSIZE_HIERARCHICAL2_512 = 14,
} J2KPRECINCTSIZE, *pJ2KJ2KPRECINCTSIZE;
This data type is used within the FILEJ2KOPTIONS structure to control the precinct size when saving JPEG 2000 files.
This feature is available in version 16 or later.
Value |
Meaning |
J2KPRECINCTSIZE_FULL |
No precinct is used, size is infinite. |
J2KPRECINCTSIZE_UNIFORM_X |
For all resoultion levels, a precinct dimemention of [X by X] will be applied. |
J2KPRECINCTSIZE_HIERARCHICAL1_X |
A precinct size of [X by X] will be applied
to the first(smallest) resoution of the image. The seconed resoultion
precinct dimension would be [2X by 2X]. The third resoltion precinct dimension
would be [4X by 4X] and so on. [64x64] level 1 |
J2KPRECINCTSIZE_HIERARCHICAL2_X |
A precinct size of [X by X] will be applied to
the first and second (smallest) resoutions of the image. The third and
fourth resoultions precinct dimension would be [2X by 2X] and so on. [64x64] level 1 |
Precincts definition and recommendation
(This feature is available in version 16 or later.)
Precincts are rectangular regions in the wavelet domain, within a given resolution level and image component that represent a spatial region on the image.
They are used for limiting the size of JPEG 2000 compressed packets and to provide a means to random access into a JPEG 2000 compressed stream. For this reason, they should be used for interactive transfer of JPEG 2000 files as in JPIP applications. In general, dividing the image into precincts is better than tiling it. So it is recommended that users compress the image as one tile and use precincts to divide the spatial region. This will give better compression ratios and image quality.
Using smaller precinct dimensions provides finer access to the compressed stream yet increases the compressed stream size. It is recommended to use J2KPRECINCTSIZE_HIERARCHICAL1_128 and no tiling to genrate JPEG 2000 files for any purpose.