Transform based on color in copy sop?

[mbdunaway]

I'm trying to create a mosaic from an image similar to the one I've attached below.

I've got a grid plugged into a copy sop with boxes, and a point node on the grid setting the color based on an image using the pic expression. I've also selected some of the brighter greys and turned them white using a group with $CR > 0.6 && $CR < 0.9, and then applying that to another point sop.

My problem now is that similar to the image, I would like for the boxes - well circles in the image - that are initially grey to scale down, preferable based on how dark they are. But I'm really stumped as to how to achieve this effect. I don't know of anyway to use the group I created (or any other similar ones) in a stamp attribute in the copy sop (only thing I could think of at the moment.)

Can anyone point me in the right direction?

[JuriBryan]

run it into a vopsop over the grid with the color information.

get the luminance of the color on the grid, plug it into a ramp node and the result of that into a multiplayer node so you can scale the value afterwards and all of that to a attribute node where you create a new attribute.

Now you can use that attribute to set the scale through the copy stamp techniques.

and you can add how much they are scaled and the difference between values with the multiplayer and which color values to scale more with the ramp.

That should give you what you want.

cheers,

Juri

[mbdunaway]

Thanks Juri!

Ended up going with a more white focused image and it works pretty well.

I really need to start using vopsop more often, its so powerful.

Edited September 23, 2013 by mbdunaway

[kev2]

Ari covers this in his procedural modellng tutorial #7:

http://www.sidefx.com/index.php?option=com_content&task=view&id=2500&Itemid=383