It can - but it can also cause color bleed in other areas.
For those who don't know, the color matrix is literally just that - a matrix (linear transformation). Every color in the HUD has an associated vector with RGB components, each between 0 and 1 (e.g. that orange color is approximately [1 0.5 0]). By default, that color matrix is identity, so the associated transformation leaves all color vectors unchanged. However, if you adjust that matrix, it will change the colors in the HUD by multiplying each color vector by the matrix.
However, as a rule of thumb (to prevent color bleed), you should have each row of the matrix add to 1, and no negative entries. Here's why:
1. Suppose a row of the matrix adds to more than 1; e.g. your matrix is [1 0.5 0 ; 0 1 0 ; 0 0 1]. In this example, the affect of that matrix on "white" [1 1 1] would be [1.5 1 1]. The game can't handle color vectors with components over 1, so the result would be "cut off" to [1 1 1] (still white). BUT - the affect of the matrix on [0.5 1 1] would ALSO be [1 1 1] (white) - so the matrix has effectively mapped two distinct colors to white.
2. Negative entries have a similar result (color bleed). The matrix [-1 0 0 ; 0 1 0 ; 0 0 1] would send [1 0 0] (red) to [-1 0 0] - which would get cut off as [0 0 0] (black).
If you like to use negative entries and rows adding up to more than 1, then go for it - it's your HUD, after all. I just find those HUDs to not look as good (and find it interesting that there is a linear algebra reason why they don't look as good).
For anyone curious, here's my HUD. It's actually hard to get a "good" red HUD, but I found one I like:
Code:
<MatrixRed> 0.9, 0.05, 0.05 </MatrixRed>
<MatrixGreen> 0.32, 0.36, 0.32 </MatrixGreen>
<MatrixBlue> 0, 0, 1 </MatrixBlue>
http://arkku.com/elite/hud_editor/#theme_0.9_0.05_0.05_0.32_0.36_0.32_0_0_1