lasm wrote:
> Hi All,
>
> <snipped...> I was trying to look for an engraved effect, the opposite
> of emboss, i.e. to make the thing look caved in, instead of
> popped out.
Short answer: "Invert bumpmap"
Long answer: Beware the sneaky qualities of human perception.
Make a grey "altitude map" of a cone (white means "high", black means "low")
0. Grey field. R = G= B= 127.
1. Foreground color white, background color black
2. Blend tool. Options: Mode -> Lighten Only. Gradient -> Radial
All other options default
3. Make a fuzzy white circle - the altitude map of a cone.
4. Filters->Map->BumpMap. Assuming default settings.
Manipulate the preview until you find your cone.
Now, one person perceives "light" streaming in from the northwest,
highlighting a raised conical hill. But, not knowing the settings,
another person perceives "light" streaming in from the southeast,
lighting the northwest rim of a conical depression. Same bitmap.
Different perceptions. You can flip the perceptions in your own
head with a little practice, so one person's emboss is another
person's intaglio. This arises from the simple, straightforward
interpretation of the first derivative of the altitude map as a kind
of "light". Unlike real light, there is an absence of other cues
to give a sense of "real" height or depth.
Given this phenomenon of dual perception, it is hard to "improve"
the bump map plugin with "absolute" embossing or intaglio properties.
Be good, be well
Garry
