Photoshop: Magnetic Lasso can not be used on Layer Mask?

  • 1
  • Problem
  • Updated 7 years ago
  • Solved
  • (Edited)
When attempting to use a Magnetic Lasso on Layer Mask, while viewing the Layer Mask content, the following Warning appears:



is this intended?
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roman weiser

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  • curious!

Posted 8 years ago

  • 1
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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Hmm. Looks like it's expecting non-alpha data to compute what it needs to compute. Chris would know more. I would say it's intended, even though it's unexpected from the user view. It might be that the warning is just a poor choice of words.
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roman weiser

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Thanks Jeffrey. What do you think would be the intention here if it in fact was intended. From the user point of view (is there any other ? ;), this seems unintuitive?
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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My guess: The intention is that the tool needs color information to calculate the magnetic effect. Agree, from the user point of view and the cryptic message, that it's unintuitive. An engineer would need to look at the code to tell exactly what's going on under the hood. We'll look into it.
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roman weiser

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Great! This would be a great addition to otherwise excellent selection tool.

As far as 'the tool looking for the color information', I was trying to find an information how exactly this tool works, but I could not find anything in depth.

I always thought it reads the pixel values from individual channels within the tool radius and then calculates the difference between the highest and lowest value at tool's mid point to establish the selection border?

Do you know how it works Jeffrey? Thanks.
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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I don't. Like I said, someone would have to look at the code. (The magnetic lasso tool's been around for a long time, so who knows which engineer implemented it. Thomas Knoll? Mark Hamburg?)
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Chris Cox

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File a bug, I think I'm the last one who touched that code.
Oh, and Scott Byer implemented it.
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Geoff Walker, Champion

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Isn't this enough of a bug report Chris?? with a smile!!
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Chris Cox

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We have an internal bug tracking system. It's important to get the bug in there so we can make sure to do regression testing. (that, and so my manager doesn't think I'm just goofing off and fixing random bugs)
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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Geoff, Chris's comments were directed at me. One of our QE (Jeanne) has this on her plate to log in the internal system on the AM.
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Jeanne Rubbo, Employee

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This is now logged in our system.
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Chris Cox

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And relatively easy to fix...
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Chris Cox

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It was disabled because normally the layer mask hides composite color data, and the edges should be calculated for the visible color data. So the layer mask is excluded from the calculations. But someone failed to make a special case for when *just* the layer mask was visible.
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roman weiser

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Makes a perfect sense Chris. I'm glad this gets addressed.
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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Official Response
We've made it so using the magnetic lasso tool can now be used on Layer Masks in Photoshop CS6. #2904586
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roman weiser

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Great!