[Radiance-general] 3.8 Falsecolor Scale
Rob Guglielmetti
rpg at rumblestrip.org
Sun Nov 12 06:21:50 CET 2006
On Nov 11, 2006, at 11:14 AM, Mark de la Fuente wrote:
> I find people understand the blue - red scale as well. Since
> falsecolor images are usually presented to clients, having "bloody"
> pictures is often a very effective communication tool. Probably
> some psychological thing that dates back to hunting mammoths saber
> tooth tigers!
I agree with the red=danger aspect; it's one of the things I like
about the scale. Blue is calming, red is alarming. And another
thing: clients freak out enough with the few colors we show them
sometimes; adding more color to the mix may make things worse. John,
I can see where you are coming from (Greg too), and I think both
scales have merits. THanks Greg for adding the "-spec" option.
>
> I suppose in Radiance one could to a pextrem command on a picture
> to get the maximum value and then use that to set the scale, but
> having it spit out something like the following can be a little
> intimidating. :)
>
> 499 499 0.000000e+00 0.000000e+00 0.000000e+00
> 322 218 2.706250e+01 2.693750e+01 2.706250e+01
>
> I've tried to use this before, but have come up with numbers I
> don't feel comfortable using.
Hmmm, what do you mean, you don't feel comfortable with these
numbers? I use pextrem all the time in conjunction with falsecolor.
If you simply run 'pextrem -o' on a radiance image and multiply the
green channel of the high pixel by 179, you have your maximum value
for the -s option.
>
> Seems like a "-s max" setting would be useful. Where setting the
> scale to "max" would automatically check the image and set the
> scale to the max pixel value automatically.
yeah, and this is probably easy for anyone who doesn't suck at
programming, as I do. I just spent longer than I care to share
trying to add such an option to falsecolor. It should be easy, but I
couldn't sort out what values to use for certain variables. Greg has
already done a lot of the work, since the -e option already has code
to run pextrem to find the max (and min) values and assign them to
variables within the script (falsecolor is actually just a shell
script). But I don't know how the scale option gets applied to the
legend. (Greg, I can share with you what I have so far, if you wanna
take it the rest of the way. )
- Rob
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