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Why do my masks look clearly like cutouts with outlines?

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Jeff RouricWhy do my masks look clearly like cutouts with outlines?
by on Aug 10, 2013 at 10:46:00 pm

Hi, so I've posted here about terrible greenscreen footage in the past, I'm still on it, and I'm trying to draw a mask around bad areas (right now it's hair) and a then duplicate the layer, so I can keep the "good" keyed footage, and work on the bad part.

So for example, I have a girl, and the rest of her portrait keys out fine (after double selective color) but her black, somewhat sheeny hair has spots of a lot fringe and weird grey bubbles. So what I'm trying to do here is

1. Draw a mask, set to None around just the bad part (back of her head area)
2. Animate the mask as needed for range 2 minutes
3. Duplicate layer (the layer is a composition in a composition in a composition)
4. Set top layer mask to Add, bottom mask to subtract.
5. Outline appears.
6. Gets bigger with effects.
7. Ask internet

Picture example:



(This is good, better than it used to be, and good enough for this project, but I need that black outline gone.)





And while we're at it, what is the "Invert" button next to the mode good for?? Isn't it just the same as choosing Add when you want to Subtract?


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mathew fullerRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 10, 2013 at 11:26:25 pm

Go to the mask in question and start messing with the expansion values.

My Work:
http://www.morecompletefx.com


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Jeff RouricRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 10, 2013 at 11:50:56 pm

Hey Matthew, thanks. -7 on the subtract layer seems to work. But why was that needed? Does masking not make a pixel perfect cut on it's own?


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mathew fullerRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 11, 2013 at 12:23:45 am

I would really have to see your project in detail to answer that question. Too many variables to guess why that was the case in your particular setup.

My Work:
http://www.morecompletefx.com


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Jeff RouricRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 11, 2013 at 10:47:26 pm

Well I'll tell you it even happened when I tried it on just a footage layer (MTS file) I'll test to see if this happens on any other project.

Ok, just tested it on a black square in a new project. Drew a mask with the mask tool (set to rotobezier) and set the mask to none. Duplicated the solid, set mask 1 to add, mask 2 to subtract. Same thing, this happens.




So this isn't limited to just my project
Is this normal? Is AE6 mask tool not pixel perfect?


When I zoom in they appear to be sets of semitransparent grey 1-2px pixels, like feathering is active. But feathering is at 0.


I'm also finding that the layer qualities are really doing weird things here

add layer is set to Draft, and the subtract layer to Best: the lines go away.
If both are set to Best, this line is here, thin
If both are set to draft, there's no lines, but a little dot.
If the add layer is set Best and the subtract layer to Draft: the lines are back, thicker

I would like to just use the Add Layer:Draft and the Subtract:Best, but I'm pretty sure those are just preview purpose anyway...

I'd really like to know why this is happening, cause sometimes expanding the mask to cover this up is bad. Please help


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mathew fullerRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 11, 2013 at 11:09:30 pm

They are never pixel perfect. You always have to expand by a pixel or so. The part of your problem I couldn't comment on is why you needed an expansion of seven pixels... seems like a lot.

Here is Why:

They are not pixel perfect because when you draw a mask it is a vector shape. The image being masked is comprised of pixels. No matter how far you zoom in your pixels will degrade but the mask will remain straight edged.

If you are using a circle mask it has to average the pixels it crosses when it renders, be it a RAM render, or a queued render.

Go into your same project... but make your mask a square rather than ellipse and I bet you a hundred bucks the edge difference goes away between the add and subtract layers. Try it.

I hope that makes sense.

My Work:
http://www.morecompletefx.com


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Jeff RouricRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 11, 2013 at 11:53:59 pm

Hey thanks man that really does make a lot of sense now, and I'm a starving artist so I'm sorry I can't get you on that hundred but you win!

The extra pixels in the other was probably due to effects/nesting structure or something, and in the future I'll prepare for that by making smaller masks than I intend.

Thanks


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mathew fullerRe: Why do my masks look clearly like cutouts with outlines?
by on Aug 12, 2013 at 4:42:58 am

No sweat. Glad you got what i was saying. Kinda hard to explain. Good luck.

My Work:
http://www.morecompletefx.com


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