Ripple (Lispix) format description#
This page summarizes the specifications for the ripple (“raw parameter list”) file format developed at NIST as native format for Lispix.
Images and spectral images or data cubes that are written in the (Lispix) raw file format, which contains just a continuous string of numbers.
Data cubes can be stored image by image, or spectrum by spectrum. Single images are stored row by row, vector cubes are stored row by row (each row spectrum by spectrum), image cubes are stored image by image.
All of the numbers are in the same format, such as 16 bit signed integer, IEEE 8-byte real, 8-bit unsigned byte, etc.
The .raw file should be accompanied by an ASCII text, tab delimited file with
the same name and .rpl extension. This “raw parameter list” file lists the
characteristics of the .raw file.
RPL keywords#
Some of the following keys are specific to HyperSpy and will be ignored by other software.
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Key Type Description
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width int pixels per row
height int number of rows
depth int number of images or spectral pts
offset int bytes to skip
data-type str 'signed', 'unsigned', or 'float'
data-length str bytes per pixel '1', '2', '4', or '8'
byte-order str 'big-endian', 'little-endian', or 'dont-care'
record-by str 'image', 'vector', or 'dont-care'
# X-ray keys:
ev-per-chan int optional, eV per channel
detector-peak-width-ev int optional, FWHM for the Mn K-alpha line
# HyperSpy-specific keys
depth-origin int energy offset in pixels
depth-scale float energy scaling (units per pixel)
depth-units str energy units, usually eV
depth-name str Name of the magnitude stored as depth
width-origin int column offset in pixels
width-scale float column scaling (units per pixel)
width-units str column units, usually nm
width-name str Name of the magnitude stored as width
height-origin int row offset in pixels
height-scale float row scaling (units per pixel)
height-units str row units, usually nm
height-name str Name of the magnitude stored as height
signal str Type of the signal stored, e.g. EDS_SEM
convergence-angle float TEM convergence angle in mrad
collection-angle float EELS spectrometer collection semi-angle in mrad
beam-energy float TEM beam energy in keV
elevation-angle float Elevation angle of the EDS detector
azimuth-angle float Elevation angle of the EDS detector
live-time float Live time per spectrum
energy-resolution float Resolution of the EDS (FHWM of MnKa)
tilt-stage float The tilt of the stage
date str date in ISO 8601
time str time in ISO 8601
title str title of the signal to be stored
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Notes#
When 'data-length' is 1, the 'byte order' is not relevant as there is only
one byte per datum, and 'byte-order' should be 'dont-care'.
When 'depth' is 1, the file has one image, 'record-by' is not relevant and
should be 'dont-care'. For spectral images, 'record-by' is ‘vector’.
For stacks of images, 'record-by' is 'image'.
Floating point numbers can be IEEE 4-byte, or IEEE 8-byte. Therefore if data-type is float, data-length MUST be 4 or 8.
The .rpl file is read in a case-insensitive manner. However, when providing
a dictionary as input, the keys MUST be lowercase.
Comment lines, beginning with a semi-colon ; are allowed anywhere.
The first non-comment in the .rpl file line MUST have two column names:
'name_1'<TAB>'name_2'; any name would do e.g. 'key'<TAB>'value'.
Parameters can be in ANY order.
In the .rpl file, the parameter name is followed by ONE tab (spaces are
ignored) e.g.: 'data-length'<TAB>'2'
In the .rpl file, other data and more tabs can follow the two items on
each row, and are ignored.
Other keys and values can be included and are ignored.
Any number of spaces can go along with each tab.