[Vis5d-users] Re: Color scale question

[Steven G. J. <st...@al...>]

If you type "s" and "l" in the color window, you can save/load the color
table to/from a file.  See also:

	http://vis5d.sourceforge.net/doc/ch06sec6.html#CH06SEC6.2

The file format, as defined in colorbar.c, is:

/*
 * Save colors to a file.
 *
 * File format is ASCII:
 *    <table_size> <minval> <maxval> <curve> <bias>
 *    <r> <g> <b> <a>         - n lines of rgba values as integers in [0,255]
 *    .....
 *    <r> <g> <b> <a>
 */

<a> is the alpha, or transparency value (0 = transparent, 255 =
translucent).  For a grayscale map, <r> <g> <b> should go linearly from 0 0
0 to 255 255 255 (giving a <table_size> of 256).

I'm not completely sure how the <curve> and <bias> values are used, from a
quick glance at the code, but it seems that they have to do with what
happens when you hit the left and right arrow keys in the color widget; I
would just leave them at their default values of 1.4 and 1.0, respectively.

Note that this also allows you to specify the minimum and maximum range of
the color table, so that you can have a consistent color map between
datasets.

(On the other hand, this makes it harder to have a set of common color
tables that you can easily apply to your data, because you have to know the
data range a priori.  Maybe I should modify the interface in Vis5d+ so that
you have the option of remapping the color range to the current data range.)

Steven