Tutorial - mtPaint - quick masking

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don570
Posts: 5528
Joined: Wed 10 Mar 2010, 19:58
Location: Ontario

Tutorial - mtPaint - quick masking

#1 Post by don570 »

Making a mask using a top layer-

Please use a recent version of mtPaint ( not version 3.31 !! )

Note that this method works with indexed images and RGB images.

Note that if you try to paste a RGB clipboard into
an indexed image then nothing will happen!!
In fact the menu item will be greyed out.
The solution is to convert the indexed image to a RGB image,
using the menu item.

Let's start with an indexed image. Make a drawing of a flower.
(save a copy to disk just in case you screw up)

Image

Make a layer on top of image
Layers > New Layer

Show the Dock
View > Show Dock

Tick the option 'Show all layers in main window'
With the transparency color =0 , the bottom layer will show through
the top layer. i.e. black is now the transparent color for
the top layer.

Choose a color that you didn't use in your drawing,
in this case color # 16 among the index colors ( a dark red)

Paint with color # 16 the mask cutout that you want,
either with a paintbrush or do a fill of a freehand selection
(see image)

Image

The next steps are very important. Do them exactly as instructed!!

TURN OFF the transparency of the top layer i.e. make
transparency color = -1

Select entire top layer.
Selection > Select all

Copy top layer and then paste it in bottom layer.

Image

Delete the top layer ( or at least make it invisible)

This next step is very important and very easy to forget!!!
Set both color A and color B to the color that you
used to paint the mask cutout ( in this example it's #16)

Choose from menu
Selection > Mask Color A,B

Image

Press ENTER then ESC to place the selection permanently.

That's it . Easy wasn't it... but it's easy to make a mistake
so practise several times till you understand and can
do it blindfolded. :lol:

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Here's some extra practice.

It's possible to have a color other than black around your
mask cutout.
Here's an example...
Modify the steps of the procedure so that pink is poured by
the paintbucket around the cutout area.

Image

Now select the top layer . Copy it and paste in the bottom layer.
Set color A and Color B to #16

Choose from menu
Selection > Mask Color A,B

and the flower should be surrounded by pink now.(see image)

Image


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A cut out can be a perfect elliptical shape. Just use
the menu item
Section > Fill ellipse

Image

TURN OFF the transparency of the top layer i.e. make
transparency color = -1

..but make sure you select the entire layer when transferring to
the bottom layer

Select entire top layer.
Selection > Select all
Here's the end result.

Image

______________________________________________________


Here's a more advanced example...

Start with a picture of a star.

Image

Make four cutouts with the color # 16 ( dark red)

Image

The end result is four meteorites crashing together.

Image

____________________________________________________

wjaguar
Posts: 359
Joined: Wed 21 Jun 2006, 14:16

Re: Tutorial - mtPaint - quick masking

#2 Post by wjaguar »

don570 wrote:Making a mask using a top layer-
One question - why not use the mask channel? I'm genuinely puzzled, given that I designed it for this exact task. ;-)
Handbook section 7.3 - "Mask"

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