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Working with region selections

Posted by Chris Northcross on November 15, 2011 at 5:39pm

So I've been playing around with the vectorizer and msg to create selection masks and I'm a little confused.

 

When I create region selections manually using the lasso, it usually results in a high contrast greyscale mask.  The non selected regions seem to be full off and the selected region is full on in terms of opacity.  When I use the vectorizer or MSG to create a selection, there seems to be a lot more grey.

 

I'd like to push these selections more towards high contrast (black and white) or, more importantly, I'm interested in creating a higher .  Any suggestions?

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Tags: mask, msg, region, selection, vectorizer
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  • Synthetik November 15, 2011 at 6:16pm

    When you use the vectorizer or MSG to generate a selection, the output of the vectorizer or MSG effect is routed to the selection buffer. So that's why you often get gray selections, because the selection is based on the luminance of the output of the effect. If the effect just output a hard contrast black and white output, then you would get full on and full off selection areas.

     

    You can always use the BW Threshold Adjust to process a grayscale selection to force it to be black and white.

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    • Aeyoss Antelope > Synthetik November 16, 2011 at 9:11am

      I am not sure how to generate a selection using the vectorizer...is this simple to explain how to do it?

      If so, thanks in advance.

      • Synthetik > Aeyoss Antelope November 16, 2011 at 9:22am

        Most Studio Artist effects have a set of generic compositing controls. One of the Composite options is 'Replace Region Selection'. This routes the output of the effect to the current selection buffer.

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    • Chris Northcross > Synthetik November 16, 2011 at 10:47am

      Hey John,

       

      Thank you much for that.

       

      Out of curiosity, the IO Threshold doesn't seem to have the same effect on a selection mask as the BW Threshold adjust does.  Why is that?

      • Synthetik > Chris Northcross November 16, 2011 at 11:10am

        I'm not sure what you mean by IO Threshold?

        • Chris Northcross > Synthetik November 16, 2011 at 11:12am

          Oh, sorry, the image operation 'Threshold'

          • Synthetik > Chris Northcross November 16, 2011 at 11:19am

            It seems the same to me when i test it. The Threshold ip op can do way more, so for anything other than the default Hard Threshold, it's going to be running a different kind of Threshold algorithm.

             

            The BW Threshold interactive Adjust interactively adjusts the threshold based on your horizontal mouse movement. barely moving the mouse is going to be a 127 threshold, and then moving the mouse left decreases that, and moving the mouse right increases that.

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