964racer Posted August 26, 2017 Share Posted August 26, 2017 I have an image file (jpg) with RGB. I would like to create an alpha channel in that image (or I can create one inphotoshop first before I bring the file into houdini) and then set the values in the alpha channel at each pixel to be a function of the RGB values. (say X^2, for example). It looks like the "function" node will allow me to operate on the RGB channels, but then how to I get the output of that into just the alpha channel (as a greyscale) and then set the RGB values to black ? Does the "channel copy" do that for me ? How would I set that up ? Thanks... Quote Link to comment Share on other sites More sharing options...
mestela Posted August 26, 2017 Share Posted August 26, 2017 A vop cop filter would be the easiest way to do this, a snippet within the vop network easier still. Attached an example... cop_example.hip Quote Link to comment Share on other sites More sharing options...
964racer Posted August 27, 2017 Author Share Posted August 27, 2017 13 hours ago, mestela said: A vop cop filter would be the easiest way to do this, a snippet within the vop network easier still. Attached an example... cop_example.hip Thank you !! I will take a look at your example... Quote Link to comment Share on other sites More sharing options...
malexander Posted August 28, 2017 Share Posted August 28, 2017 Channel Copy with the following settings will copy the luminance to A and set C to black: Target: New Plane: A Source: Input 1: C Target: C Source: Set to 0 (black) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.