[Qgis-user] Raster Calculator Expression to determine color

[Nyall Dawson]

On 31 Jul 2015 11:07 am, "Nick Papadonis" <npapadonis at gmail.com> wrote:
>
> HI Folks,
>
> I’m trying to use the following expression to pick up the red colored
routes on a map in which I used the info pointer tool to get the band
values for the color.
>
> (“m at 1" < 238 AND “m at 1" > 213 AND “m at 2" < 123 AND “m at 2" > 98 AND “m at 3" <
125 AND “m at 3" < 99) * 1

Should that last check be "m at 3" > 99?

Nyall

>
> Unfortunately, when this expression is used the resulting map is black
with no other pixels for the detected color.
>
> If I break down this expression to a simple “greater than” line for
single band, then things work.
>
> Does anyone know where this expression needs to be corrected?
>
> Thanks again,
> Nick
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