TIFF CHANGE INFORMATION
This document describes the changes made to the software between the
previous and current versions (see above). If you don't
find something listed here, then it was not done in this timeframe, or
it was not considered important enough to be mentioned. The following
information is located here. A change summary is also provided by the
ChangeLog file included in the release package and by the Git commit
- Make defer strile offset/bytecount loading available at runtime
and add per-strile offset/bytecount loading capabilities. Part of
this commit makes the behaviour that was previously met when libtiff
was compiled with -DDEFER_STRILE_LOAD available for default builds
when specifying the new 'D' (Deferred) TIFFOpen() flag. In that
mode, the [Tile/Strip][ByteCounts/Offsets] arrays are only loaded
when first accessed. This can speed-up the opening of files stored
on the network when just metadata retrieval is needed.
Another addition is the capability of loading only the values of
the offset/bytecount of the strile of interest instead of the
whole array. This is enabled with the new 'O' (Ondemand) flag of
TIFFOpen() (which implies 'D').
The public TIFFGetStrileOffset[WithErr]() and
TIFFGetStrileByteCount[WithErr]() functions have been added to
API. They are of particular interest when using sparse files (with
offset == bytecount == 0) and you want to detect if a strile is
present or not without decompressing the data, or updating an
existing sparse file.
- The BigTIFF writer now optimizes file size by using 32-bit LONG
values (rather than 64-bit) where it is reasonable and safe to do
so. Likewise, the 16-bit SHORT type is used when possible for
CHANGES IN THE SOFTWARE CONFIGURATION:
- The WIN32 build now uses tif_win32.c when building with CMake.
- Properly set value of HOST_FILLORDER to LSB2MSB for Windows
CMake builds. It was not being properly set!
CHANGES IN LIBTIFF:
Changes in the libtiff library may be viewed on-line
New function TIFFReadFromUserBuffer() which replaces the use of
TIFFReadEncodedStrip()/TIFFReadEncodedTile() when the user can
provide the buffer for the input data, for example when he wants
to avoid libtiff to read the strile offset/count values from the
New functions TIFFDeferStrileArrayWriting() and TIFFForceStrileArrayWriting()
Those advanced writing functions must be used in a particular sequence
to make their intended effect. Their aim is to control when/where
the [Strip/Tile][Offsets/ByteCounts] arrays are written into the file.
The purpose of this is to generate 'cloud-optimized geotiff' files where
the first KB of the file only contain the IFD entries without the potentially
large strile arrays. Those are written afterwards.
CHANGES IN THE TOOLS:
CHANGES IN THE CONTRIB AREA: