.. meta::

   :description: Kdenlive Video Effects - Alpha Shapes (Mask)
   :keywords: KDE, Kdenlive, video editor, help, learn, easy, effects, filter, video effects, alpha shapes (mask), mask

.. metadata-placeholder

   :authors: - Claus Christensen
             - Yuri Chornoivan
             - Ttguy (https://userbase.kde.org/User:Ttguy)
             - Bushuev (https://userbase.kde.org/User:Bushuev)
             - Bernd Jordan (https://discuss.kde.org/u/berndmj)

   :license: Creative Commons License SA 4.0


Alpha Shapes (Mask)
===================

.. figure:: /images/effects_and_compositions/kdenlive2308_effects-alpha_shapes_mask.webp
   :width: 365px
   :figwidth: 365px
   :align: left

.. sidebar:: |kdenlive-show-video| Alpha Shapes (mask)

   :**Status**:
      Maintained
   :**Keyframes**:
      Yes
   :**Source library**:
      MLT
   :**Source filter**:
      mask_start
   :**Available**:
      |linux| |appimage| |windows| |apple|
   :**On Master only**:
      No
   :**Known bugs**:
      No

.. rst-class:: clear-both


.. rubric:: Description

This effect essentially works like the :doc:`Alpha Shapes </effects_and_compositions/video_effects/alpha_mask_keying/alpha_shapes>` effect but takes a snapshot of the frame before it draws simple shapes into the alpha channel. Use it together with the :doc:`/effects_and_compositions/video_effects/alpha_mask_keying/mask_apply` effect that uses a transition to composite the current frame's image over the snapshot. The typical use case is to add effects in the following sequence:

 Alpha Shapes Mask (this effect) -->  zero or more effects (e.g. :doc:`Blur </effects_and_compositions/video_effects/blur_and_sharpen/gaussian_blur>`, :doc:`Cartoon </effects_and_compositions/video_effects/stylize/cartoon>`) -->  Mask Apply [--> more effects if needed]


.. rst-class:: clear-both


.. rubric:: Parameters

.. list-table::
   :header-rows: 1
   :width: 100%
   :widths: 20 10 70
   :class: table-wrap

   * - Parameter
     - Value
     - Description
   * - Shape
     - Selection
     - Controls the shape of the area of opacity that the effect will create.
   * - Operation
     - Selection
     - Defines what is to happen when you have more than one alpha effect on the clip
   * - Position X / Y
     - Integer
     - Defines the position of the shape on the screen. The range of values is from 0 to 1000 where 500 defines the middle of the screen.
   * - Size X / Y
     - Integer
     - Defines the size of the shape. The range of values is from 0 to 1000 where 500 defines 100%,
   * - Tilt
     - Integer
     - Controls the angle the shape appears on the screen. The units are in 1000ths of a full rotation. For example, a value of 250 is one quarter of a circle turn and 500 is a 180-degree turn. That means, 1000 tilt units = 360 degrees.
   * - Transition width
     - Integer
     - Defines the width of a border on the shape where the transparency grades from the inside to the outside of the shape. Can be used for feathering or creating a frame.
   * - Min
     - Integer
     - 
   * - Max
     - Integer
     - 

The following selection items are available:

:guilabel:`Shape`

.. list-table::
   :width: 100%
   :widths: 20 80
   :class: table-wrap

   * - Rectangle
     - Draws a rectangle
   * - Ellipse
     - Draws an ellipse/circle
   * - Triangle
     - Draws a triangle
   * - Diamond
     - Draws a diamond

:guilabel:`Operation`

.. list-table::
   :width: 100%
   :widths: 20 80
   :class: table-wrap

   * - Write On Clear
     - Existing alpha mask is overwritten
   * - Max
     - Take the maximum between the existing alpha mask and the mask generated by this filter
   * - Min
     - Take the minimum between existing alpha mask and mask generated by this filter
   * - Add
     - Add the existing alpha mask and the mask generated by this filter
   * - Subtract
     - Subtract from the existing alpha mask the mask generated by this filter


.. rubric:: Notes

.. seealso:: :doc:`Alpha Shapes</effects_and_compositions/video_effects/alpha_mask_keying/alpha_shapes>` effect for more details and examples for the various shapes and operations.