View Full Version : Control Values on a "per pixel" basis

Robert Zeltsch
08-22-2003, 06:36 AM
Hello everyone,

I`m new to DFX+ too - like many other users here.
... and I have a question. ;)

How can I control a slider value (for example "blur size" in the Blur Tool) on a "per pixel basis" by usage an underlying greyscale image.

An "verbal-expression"in the image]=[Blur Size from Slider]*[value of the greyscale image]

With this I could vary the blur size over the image. My first try was to apply a bitmap mask to control the blur. But with this way I can only BLEND a constant Blur into the image. So it looks like a blurred one is blended by a mask over the original image. That is not what I wanted. :hmm:

Can anyone help me?

(I`m using modules 1 and 4)

Thank you!!

08-22-2003, 11:52 PM
Hi Robert,

You are on the right track with the bitmap mask. Have you selected which channel the mask is affected by? (R , G, B, A, Saturation, Luminance, etc...) I think the default is Alpha, which means it will affect the entire image (the Alpha channel will be all white or black, unless an Alpha channel is present in the image). By choosing a colour channel, it should work. I can send you a small flow if you want to see what I mean.


Justin W.

Robert Zeltsch
08-23-2003, 04:43 AM
Thanks a lot, but changing the alpha to another channel is that what I have tried until now.

A user in the cgtalk forum gave me the right idea. To achieve the desired result put the greyscale image into the z-buffer with the channel boolean tool. After that you can adjust the blur with the depth blur tool.

Doug Nicola
08-24-2003, 01:00 PM
I don't know if this is directly related to solving your problem, but here is a free tool from www.komkomdoorn.com


"number probe [1.4o, level 1] - Your wish come true. This tool allows you to control any numeric parameter by the pixel color or luminosity at a certain position or rectangular region of an image."

direct link:


Doug Nicola
08-24-2003, 01:31 PM
Actually, after looking at the number probe tool more, this looks exactly like what you might want (if you want a certain kind of direct control).

You set up the tool by choosing "modify with" and then "probe" on any numeric value (e.g. "Blur Size" on Blur/Sharpen tool).

And then you have an interactive tool on your image and two panels under your modifiers tab.

Put your grayscale image (or whatever you want to use!) under "image to probe."

And of course you can set up as many Blurs/probes as you want.

Edit: I understand this isn't what you want when you need "pixel by pixel" control over your entire image, but this tool could be useful in a host of other ways.


Doug Nicola
08-24-2003, 01:32 PM
And this:

Robert Zeltsch
09-07-2003, 11:17 AM
Thanks for the info! :)

The ground idea is cool, but - like you said - it works not on an pixel per pixel base. hm...

But it could be a cool idea to control ALL values in this way...:rolleyes: