Technical Slop

Solid

So many things go into using Displace. Almost too many things to make it understandable. But that is a part of what makes Displace so powerful -- all those options. Right now, don't worry too much about all those things. Just worry about positive and negative values entered into the Displace dialoge box, and what the DMap looks like. Right now, the DMap is just a White square in a Gray border (you'll see).

Meet Biker Chic. Don't ask because I don't know. She's just one of those things with me.

She is what we will be experimenting with. See that yellow border around her? That's a part of the image. It's to help show what's going on when we use her for Displacing.

This is our first DMap. Pretty plain, isn't it? Don't fret --things will get complicated down the road. For now, simple is good. And this is a one channel PSD. A Greyscale doc.

See? A White square in a Gray border.

What does it do to Biker Chic? First we'll try a positive percentage for Horizontal Displacement.

See what happened? See the yellow line that was grabbed from the right border and her face was moved over with it?

What happened was Displace looked at the White in DMap and grabbed pixels appropriately. It grabbed from the right.

That's what White does in a DMap with a positive percentage in the Horizontal.

Okay. Let's look at that in a little bit more detail. Sounds good to me.

The D-Map is overlayed the picture of Biker Chic (using Stretch to Fit).

First, it checks the value of a pixel in the D-Map (in this case, the upper-right of the White square).

Then it grabs a certain distance based on the brightness value of that particular pixel in the D-Map.

Then it grabs that pixel from the picture and pulls it onto itself -- in the picture itself..

Jeez. Hopefully the graphic to the left explains this better than I can verbally.

What does a negative value do?

It grabs from the left. (No more big graphics like above.)

So, White grabs from the right with a positive value and White grabs from the left with a negative value.

Okay, that's just Horizontal. What about Vertical?

Glad you asked.

Heh. White grabs from below with a positive Vertical percentage.

Can you guess what a negative value does?

Did you guess right? I hope so.

Okay, so that was a lot fun -- boring, but fun.

Nothing like playing with just one percentage at a time to get the feel for Displace.

Ready for some reverse-ngineering with our plain DMap? By that I mean taking our current DMap and getting to do what we want it to do.

What we want it to do now is take the upper-right hand corner and place it in the middle. We want to grab from above and to the right. That means that the Horizontal percentage is positive and our Vertical percentage is negative. Right?

Yep. That did the trick.

So, what does this mean? It means that we can use the same DMap to grab from anywhere within Biker Chic just by using positive/negative values for Horizontal and Vertical.