Data from: Image Calibration and Analysis Toolbox – a free software suite for measuring reflectance, colour, and pattern objectively and to animal vision

1. Quantitative measurements of colour, pattern, and morphology are vital
to a growing range of disciplines. Digital cameras are readily available
and already widely used for making these measurements, having numerous
advantages over other techniques, such as spectrometry. However,
off-the-shelf consumer cameras are designed to produce images for human
viewing, meaning that their uncalibrated photographs cannot be used for
making reliable, quantitative measurements. Many studies still fail to
appreciate this, and of those scientists who are aware of such issues,
many are hindered by a lack usable tools for making objective measurements
from photographs. 2. We have developed an image processing toolbox that
generates images that are linear with respect to radiance from the RAW
files of numerous camera brands, and can combine image channels from
multispectral cameras, including additional ultraviolet photographs.
Images are then normalised using one or more grey standards to control for
lighting conditions. This enables objective measures of reflectance and
colour using a wide range of consumer cameras. Furthermore, if the
camera's spectral sensitivities are known, the software can convert
images to correspond to the visual system (cone-catch values) of a wide
range of animals, enabling human and non-human visual systems to be
modelled. The toolbox also provides image analysis tools that can extract
luminance (lightness), colour, and pattern information. Furthermore, all
processing is performed on 32-bit floating point images rather than
commonly used 8-bit images. This increases precision and reduces the
likelihood of data loss through rounding error or saturation of pixels,
while also facilitating the measurement of objects with shiny or
fluorescent properties. 3. All cameras tested using this software were
found to demonstrate a linear response within each image and across a
range of exposure times. Cone-catch mapping functions were highly robust,
converting images to several animal visual systems and yielding data that
agreed closely with spectrometer-based estimates. 4. Our imaging toolbox
is freely available as an addition to the open source ImageJ software. We
believe that it will considerably enhance the appropriate use of digital
cameras across multiple areas of biology, in particular researchers aiming
to quantify animal and plant visual signals.