Nearly Raw Raster Data
Nrrd is a library and file format designed to support scientific
visualization and image processing involving N-dimensional raster
data. Nrrd stands for "nearly raw raster data". Besides dimensional
generality, nrrd is flexible with respect to type (8 integral types, 2
floating point types), encoding of written files (raw, ascii, hex, or
gzip or bzip2 compression), and endianness (the byte order of data is
explicitly recorded when the type or encoding expose it). About two
dozen operations are implemented, including simple things like
quantizing, slicing, and cropping, and fancier things like projection,
histogram equalization, and filtered resampling (up and down) with
arbitrary seperable kernels.
This document aims to describe the NRRD file format and the
nrrd library which can read and write NRRD files. Various
examples illustrate the variety of possible nrrd operations available
in the nrrd library, which are also accessible from the
command-line "unu" program. Impatient readers should look at
"Example NRRD files", "Demonstrations using nrrd", and "Advocacy".
In these pages, "NRRD" refers to the file format, "Nrrd"
refers to the C struct defined in nrrd.h, "nrrd"
refers to the library containing all the nrrd functions, , and "nrrd"
is a general term for all of these.
- Introduction: What kind of data
nrrd can represent, with a discussion of dimension, axes, and scalar
types.
- File format: How to get data into
and out of nrrd. Definition of the NRRD file format.
- Example NRRD files: A
variety of NRRD file format examples, as well as PPM, PGM, and text
files which encode nrrd information.
- NRRD-Compatible file
formats: How NRRD plays well with PPM, PGM, and plain text
files. Information normally found in the NRRD header can be
losslessly encoded in these formats.
- Nrrd Data structure:
Basic information about the Nrrd data structure, and
description of the nrrd functions for creating and destroying
Nrrds.
- nrrd Library Description: High-level
documentation for the nrrd library and its various functions
for manipulating Nrrds. Also describes the connection
between the nrrd library and the Utah Nrrd Utilities
command-line program "unu".
- Demonstrations of using nrrd: A
series of examples of how the nrrd library and/or the
"unu" program can be used to do useful things.
- Advocacy: Why you should
use nrrd.
- Credits.
Who else has helped with nrrd.