Colour scale / Colour tables
The application provides various colour scales (colour tables) used to assign colours to numerical results within graphical evaluations. Particular selection of a colour scale depends on visualisation needs of the user.
In addition to the obligatory RGB and RGB_INV tables, following colour tables are available:
The grey scale provides the most simple palette of colours. Temperature values are transformed to brightness values, similarly as it is done by camera. This palette is useful for exceptionally neutral evaluations.
Especially for temperature images it is natural to use the colour scale of glowing body: Cold objects display dark and reddish, hot show in bright in yellow or even white. The contrast is moderate, but higher then of the neutral grey scale.
The contrast of a thermogram can be enhanced by adding the colour of violet between red and the black (= cold) end.
Alternatively the contrast of a thermogram can be enhanced also by using the scale of hot stars as it is used by astronomy.
To carry the contrast to extreme by adding as many colours to the scale as possible. One can use psychological perception people see as "cold" and "warm" colours, and assign them accordingly to temperatures. None of colours used is repeated to avoid any ambiguity. It is worth to observe, that even small value errors will be visible now.
Cartography uses an alternative kind of colouring allowing perception of even very small value differences. Psychologically "colder" colours are assigned to smaller values and "warmer" colours apply to higher values.
There are some use cases making conventional colorizing not suitable - for example when the picture of a thermogram shall allow derivation of energy balance. For such situations a symmetrical colouring is more reasonable and the centre jump point could be set to zero.
Remark: The current number of colour intervals used within the colour table is 2048 (more colours „cannot be seen simultaneously by human eye“).
See also: 3D evaluations