Provides tools for image manipulation that will help you to
quantify plant leaf area, disease severity, number of disease lesions,
and obtain statistics of image objects such as grains, pods, pollen,
leaves, and more. Tools to segment images and create binary images
using the method of automatic threshold selection proposed by
Otsu (1979) <doi:10.1109/tsmc.1979.4310076> are also provided.

This package uses unidimensional item response theory methods to compute linking
constants and conduct chain linking of tests for multiple groups under a nonequivalent groups
common item design.  It allows for mean/mean, mean/sigma, Haebara, and Stocking-Lord calibrations
of single-format or mixed-format dichotomous (1PL, 2PL, and 3PL) and polytomous (graded response
partial credit/generalized partial credit, nominal, and multiple-choice model) common items.
Tue Sep  4 02:09:14 2007; Jonathan Weeks

IRT Separate Calibration Linking Methods
Thu Sep 13 05:49:11 2007; Jonathan Weeks

Wed Sep 19 14:48:24 2007; Jonathan Weeks

This package uses item response theory methods to compute linking constants and conduct
chain linking of tests for multiple groups under a nonequivalent groups common item design.
It allows for mean/mean, mean/sigma, Haebara, and Stocking-Lord calibrations of dichotomous
(1PL, 2PL, and 3PL) and/or polytomous (graded response, partial credit/generalized partial
credit, nominal, and multiple-choice model) common items.
Sun Dec  2 11:36:20 2007; Jonathan Weeks

Tue Dec  4 02:41:50 2007; Jonathan Weeks

Sun Sep  7 16:45:01 2008; Jonathan Weeks

Wed Sep 10 05:17:16 2008; Jonathan Weeks

Fri Sep 26 09:02:17 2008; Jonathan Weeks

Mon Jan 26 12:53:47 2009; Jonathan Weeks

R (>= 2.7.2), methods, statmod, lattice, MASS
This package uses item response theory methods to compute
linking constants and conduct chain linking of unidimensional
or multidimensional tests for multiple groups under a
nonequivalent groups common item design.  The unidimensional
methods include the Mean/Mean, Mean/Sigma, Haebara, and
Stocking-Lord methods for dichotomous (1PL, 2PL and 3PL) and/or
polytomous (graded response, partial credit/generalized partial
credit, nominal, and multiple-choice model) items.  The
multidimensional methods include the Reckase-Martineau method
and extensions of the Haebara and Stocking-Lord method using a
single dilation parameter, multiple dilation parameters, or the
Oshima, Davey, & Lee approach for multidimensional extensions
of all the unidimensional dichotomous and polytomous item
response models.  The package also includes functions for
importing item and/or ability parameters from common IRT
software and ploting item characteristic/category curves or
surfaces and vector plots.