Contents || Index
04/17/2008

Spectrum Images

Spectrum images are data cubes  recorded spectrum by spectrum and loaded by Lispix into a vector cube.. Each pixel in the cube, as Lispix displays it, represents an x-ray energy spectrum.  Each channel in the spectrum is an integer, representing x-ray counts at that energy, for a particular location in the sample.

Other data cubes are recorded image by image.  These cubes are often loaded from a folder of images, and they are represented in Lispix as an image cube, rather than a vector cube. 

Data cubes often are large - larger than Lispix's memory capacity.  Image cubes can be examined piece by piece simply by loading only a portion of  the images in the cube:  select the images when using **Data Cube** / read / ..., or modifying the depth and offset parameters in the Import / Export Tool.  Vector cubes, or spectrum images, have their own peculiar issues:

Reading Large Spectrum Images

New - file based methods:  Lispix will work with large Spectrum Images of most any size, if they are recorded in .raw or .spd format.  (New as of 4/08.)

 

Old - memory based methods:   Truncate and clip the spectral data as it is being loaded.

If the data cube is a spectral image, i.e. if the record-by parameter in the rpl file is :vector and not :image, then upon opening the file, Lispix will ask if you want to truncate the data to fewer bytes (if the data has more than one byte), and how many channels you wish to load, starting with channel 0.  If you elect to reduce the data in this way, Lispix will record the reduced data cube after it is loaded, in a file with "m-" appended to the front of the original file name, standing for "modified".  Even if you do not reduce the cube on reading, and Lispix manages to load the whole thing, then if Lispix was able to automatically reduce the data by examining the maximum channel count for the whole cube, Lispix will then record the reduced cube with "m-" appended to the front of the name.

Note about automatically recording the reduced spectral image:  The cube may be reduced in a variety of ways - to two bytes or only one byte per channel, or to 1024 or 2048 channels down from 4096.  Any of these will be recorded as "m-" plus the original file name,  To make unique file names, rename the cubes and the matching rpl files in the Windows Explorer.