In the PCT Range editor panel, the user can identify two endpoints within the image histogram to which a set of colours can be applied. The colours can then be directly mapped, stretched or compressed to fit within a specified range of grey levels.
General steps:
A colour range is set from the colour selection area. The two markers off the colour bar allow the user to specify exactly what the starting and ending colours are.
The next step is to move the left and right marker of the graph (histogram) to identify where the colours that were picked should be applied.
The lower section of the panel displays the created PCT for previewing the selections. This section allows the user to map/stretch or compress the colours within the chosen range of grey level values.
The slider bar allows the user to shift the colours either to the left or to the right. The left and right push buttons can be used to shift the colours by one increment.
See Also: PCT Editing
The colour bar displays the colours that the user picks. The left and right marker text fields below the colour bar displays the grey level values represented by the markers on the colour bar. They can also be used to move these markers to a specific value. These values can also be modified by dragging the markers with the mouse. In the standard mode, the markers are filled with the colours they are pointing to. In custom mode the markers are filled with the choices made for the first and last colours in the interpolation.
The colour bar will be updated to display the colours that correspond to the predefined PCT selected by the user.
The ``Use Original PCT'' push button will change the colour bar to reflect the PCT loaded in ImageWorks by the user, if applicable. If you have loaded a PCT and want to use it, you need to press this button to load in the PCT to the colour bar.
See Also: PCT Editing
By using the colour mixing panel, the user can specify the first colour and the last colour for a customized colour bar.
After the selection of the two endpoint colours, pressing the ``Interpolate'' push button will do a linear interpolation of colours from the first colour to the last colour. The result of the interpolation is displayed in the colour bar.
The two markers on the colour bar may be moved left or right, and then pressing the ``Interpolate'' push button again will change the contents of the colour bar such that the colours within the colour bar are linearly interpolated between these end points.
There are two markers that allow the user to specify the range of grey levels in which to apply the selected colours. For convenience, two input textfields are also available to specify exactly where to place the markers.
There is an option menu which allows the user to control values that are outside the specified range of grey levels. If the option menu is set to black, then all values outside the specified range are set to black. Similarly if the option menu is set to white, then the outside ranges are set to white. The Ignore option will not alter existing values that are outside the range of the PCT.
The ``Compress'', ``Map'', or ``Stretch'' push button is used to actually display the selected colour scale in the image window. Until this button is pressed, you will not actually see the effects of changing the colour bar or histogram.