> when the stickers were initially
> offered for sale, it was noted that the blue stickers are not very
visible,

I really don't think you understand color dynamics... Color means noting
without contrast.... With thin lines and a clear background of our stickers,
visibility is more dependant on what happens to be behind the sicker than on
the color of the lines.... it is contrast that makes something pop to the
eye... not the color of the sticker lines...

If the sticker design were printed on a contrasting background color (rather
than clear) they would be consistently visible....

> for those who wanted to be NOTICED, the yellow stickers were considerably
> more visible.

NOT SO... Not on a yellow van.... or if there is something yellow (or
anything light colored) inside the van behind the sticker :)

> The whites fall somewhere between.

NOT SO... Not on a white van or with anything light colored behind the
sticker...

My wife's van has the
> yellow stickers, and I can see them from a good quarter mile, and possible
> farther.

AGAIN, DEPENDS ON THE BACKGROUND... AND EVEN WITH THE MOST CONTRASTING
CONTENTS INSIDE THE VAN THE THIN LINES OF THE DESIGN MAKE IT SO YOU REALLY
HAVE TO LOOK FOR THE STICKER...

A SOLID, BRIGHT BACKGROUND COLOR (LIKE THE RED OF THE SCUBA DIVER STICKER)
WOULD MAKE IT SO YOU DON'T HAVE TO CONCENTRATE TO LOOK FOR OUR STICKER... IT
WOULD POP OUT AT YOU....

ALSO, having three colors complicates automatic recognition because your
always having to look for a variety of colors... you don't get automatic
recognition like the scuba sticker does... it's the same color in all
locations.

Bill