Tim's archive

5/15/2008

• Add function to generate test images with different data types. We would like populate the images with known values including Nan, Inf,Min,Max.
• We use these test images to check cfitsio wrapper read/write compress/uncompress functionalities.
• The first test shows that images (of bytes, shorts, longs, float, double) seem to go through compress/uncompress without rounding errors.
• Image (double) with NaN seem to change the value of the whole row to NaN. We will do more tests.
• Art found an unexpected result when writing image with signed bytes. I help searching for info on how cfitsio library handling these cases.

• 5/8/2008
• Found the bug in cfitsio_read_file() that fails to read compress file.
• We now have away to pass compression parameters through DRMS, using extended filename. So, we remove this setting at lower level.
• Move cfitsio functions which use headers to a separate file.
• Add code to modify keylist to reflect current image dimensions and support export senario.

• 4/10/2008
• We have tested many low level functions that cfitsio library provides for writing multi-dimension image to fits file format.
• We are wrapping them into fews functions that we are going use and we choose to develop functions for image cube first.
• We almost finish with implementing this list
• cfitsio_create_cube(filename, data_type, dimensions)
• cfitsio_apend_slices(filename, axis, number_of_slices)
• cfitsio_insert_slices(filename, axis, number_of_slices, begin_slice)
• cfitsio_read_slice(filename, axis,slice_number, buffer)
• cfitsio_write_slice(filename, axis, slice_number, buffer)
• cfitsio_read_stripe(filename, fpixel, lpixel, buffer)
• cfitsio_write_stripe(filename,fpixel, lpixel, buffer)
• cfitsio_cascade_cube(filename1, filename2,axis)
• cfitsio_truncate_cube(filename,axis,number_of_slices)

• 4/3/2008
• Add low level functions to CFITSIO which creates image cubes, slices, stripes of different data types.
• It enables image slices extract and insert in different plans.
• The image slices and cubes are read and written to fits files.

• 3/20/2008
• Continue testing low level function calls to CFITSIO library.
• Create image cube, read, write stripes, slices, copy data block in place, in different directions.
• We try to wrap these functions, making it easy to use first.
• Then, study the (read) access time when 3D images are compressed and read back with different tile sizes and different directions

• 3/13/2008
• Add a small structure to cfitsio.c which contains the keys that drms_segment uses, so we parse the key list only once.
• Continue to work with Art to integrate cfitsio.c into drms_segment calls.
• Begin to work on cfitsio functions to read/write data slices.

• 2/28/2008
• Read drms_fits.c to see how to pass parameters to/from cfitsio. A great portion drms_fits.c maybe no longer needed, so we will try to call cfitsio.c directly drms_segment.c.
• Met with Art to for cvs checkin location. Art will create the make file for cfitsio for different types of builds.
• Note: The C library from HEASARC called "fitsio", cfitsio is our wrapper.
• We decide to remove a small header at the beginning of the data block, containing the basic info (naxis, naxes, bitpix,...) These info will be made available by caller function.
• Try to combine writing and compressing to file into one step for efficiency