The importance of developing post-processing methodologies to aid in the interpretation of
luminescence and other multispectral images is increasingly being recognised, both as a
means to extract the maximum information from the images but also to standardise images
and make them device-independent, allowing them to be compared more directly. Many of
the approaches reported’? have included corrections for some of the experimental factors
and phenomena discussed in Chapter 1. Some have included existing nip2 tools (see
below), such as that used to carry out colour corrections based on use of a Macbeth target.
Others have proposed similar workflow approaches but have built these into proprietary
software programs, such as Matlab, which require the purchase of these specialist programs
and considerable knowledge of their use by the user. In almost all cases, the post¬
processing methodologies have been slow to implement, are in many cases at least partly
Subjective and require the use of several different software programs making them
unsuitable for wide adoption by a broad range of users with varying understanding of the
mathematical processes involved.
The current approach has developed a unified set of user-friendly tools housed in a
dedicated ‘workspace’ for nip2, the graphical interface of the free image processing system
VIPS° (see below). This chapter describes how the transformations outlined described in
Chapter 1, and the data collected as a result of the acquisition protocols outlined in Chapter
2, have been combined in a nip2 workspace to form a series of image correction workflows.
Prior to carrying out any post-processing of the images recorded however, these must first
be correctly transferred from the camera and converted to TIFF files from their native digital
camera RAW formats. Instructions on how to carry this out are provided below, together with
instructions on how to download and install the nip2 software and the workspace developed
to undertake the post-processing. Finally, the four workflows for the correction of the
multispectral image sets as proposed in Chapter 1 and collected as described in Chapter 2,
are described and a full set of instructions for their use is provided, together with the post¬
processing requirements (the images or other information) required to complete them. The
workflows are considered in terms of the two categories of images established in previous
chapters: reflected and photo-induced luminescence images. Some quick reference
instructions, intended for use once familiarity with the operation of the workspace and the
various workflows for the correction of the image types described has been achieved, are
included in Appendix 3.
a. Transferring images from the camera and converting
from RAW
As discussed briefly in Chapter 1, whenever a captured image is converted into a standard
JPEG or TIFF file by the camera or the RAW image conversion software (such as Adobe
Photoshop or the software from the camera manufacturer), a number of processes are
carried out to the data from the sensor. These are summarised in Figure 3-1.
Version No. 1.0 103 Date : 14/10/2013