class CrImage::Mask

• CrImage::Mask
• Reference
• Object

Overview

Mask is a wrapper around BitArray, where each flag represents a boolean bit of information about a pixel from an image. This can include whether a particular pixel has a value within certain conditions, OR if that pixel should be zeroed out or not.

See #[]= methods below for examples of how to manually construct masks.

(x,y) - coordinates. Represent these positions in a Mask of size 10x10:

[
  (0,0), (0,1), (0,2), (0,3), (0,4), (0,5), (0,6), (0,7), (0,8), (0,9),
  (1,0), (1,1), (1,2), (1,3), (1,4), (1,5), (1,6), (1,7), (1,8), (1,9),
  (2,0), (2,1), (2,2), (2,3), (2,4), (2,5), (2,6), (2,7), (2,8), (2,9),
  (3,0), (3,1), (3,2), (3,3), (3,4), (3,5), (3,6), (3,7), (3,8), (3,9),
  (4,0), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6), (4,7), (4,8), (4,9),
  (5,0), (5,1), (5,2), (5,3), (5,4), (5,5), (5,6), (5,7), (5,8), (5,9),
  (6,0), (6,1), (6,2), (6,3), (6,4), (6,5), (6,6), (6,7), (6,8), (6,9),
  (7,0), (7,1), (7,2), (7,3), (7,4), (7,5), (7,6), (7,7), (7,8), (7,9),
  (8,0), (8,1), (8,2), (8,3), (8,4), (8,5), (8,6), (8,7), (8,8), (8,9),
  (9,0), (9,1), (9,2), (9,3), (9,4), (9,5), (9,6), (9,7), (9,8), (9,9),
]

And every position is a Bool value.

Different ways to refer to coordinates:

mask.at(0, 0)    # => (0,0)
mask[0, 0]       # => (0,0), same as .at(0, 0)
mask[0..1, 4]    # => (4,0), (4,1)
mask[3, 3..5]    # => (3,3), (3,4), (3,5)
mask[2..3, 4..5] # => (2,4), (2,5), (3,4), (3,5)

See Operation::Crop and Operation::MaskApply for how this can be useful

Included Modules

• CrImage::Map(Bool)

Defined in:

cr-image/mask.cr

Constructors

• .new(width : Int32, height : Int32, initial : Bool = true)

  Construct a new Mask of width x height, preset to initial

• .new(width : Int32, height : Int32, int : Int)

  Construct a new Mask from an integer (useful for testing or small mask construction)

• .new(image : Image, initial : Bool = true)

  Construct a new Mask from the dimensions of passed in image with an initial bit

• .new(width : Int32, bits : BitArray)

  Construct a new Mask with a set width and bits from #bits

• .new(width : Int32, height : Int32, &block : Int32, Int32 -> Bool)

  Construct a new Mask of width x height using &block to determine if a bit should be true or not (passed in x and y coordinates)

• .new(other_bits : Array(BitArray))

  Construct a new Mask from an array of BitArray.

Instance Method Summary

• #==(other : Mask)
• #[](xstart : Int32, xcount : Int32, ystart : Int32, ycount : Int32) : Array(BitArray)

  Return an Array(BitArray) for the partial box (of partial rows and partial columns) of this mask.

• #[](x : Int32, y : Int32) : Bool

  Return the bit at x and y

• #[](xs : Range, y : Int32) : BitArray

  Return a new BitArray corresponding to the partial row specified

• #[](x : Int32, ys : Range) : BitArray

  Return a new BitArray corresponding to the partial column specified

• #[](xs : Range, ys : Range) : Array(BitArray)

  Return an Array(BitArray) for the partial box (of partial rows and partial columns) of this mask.

• #[](index : Int32) : Bool

  Return the bit at index

• #[]=(x : Int32, y : Int32, value : Bool) : Bool

  Set the bit for coordinate x and y

• #[]=(xs : Range, y : Int32, value : Bool) : Bool

  Set the bits for partial row xs at column y

• #[]=(x : Int32, ys : Range, value : Bool) : Bool

  Set the bits for row x and partial columns ys

• #[]=(xs : Range, ys : Range, value : Bool) : Bool

  Set the bits for partial rows xs and partial columns ys

• #[]?(x : Int32, y : Int32) : Bool | Nil
• #[]?(index : Int32) : Bool | Nil
• #|(other : Mask) : Mask
• #apply(image : Image) : Image

  Apply this mask to the provided image with Operation::MaskApply#apply

• #apply(image : Image, &block : UInt8, ChannelType, Int32, Int32 -> UInt8) : Image

  Apply this mask to the provided image with Operation::MaskApply#apply

• #at(index : Int32) : Bool

  Return the bit at index

• #bits : BitArray
• #clone

  Create a new Mask from this one without modifying it

• #closing(*, diagonal : Bool = true) : Mask

  Closing operator

• #closing!(*, diagonal : Bool = true) : Mask

  Closing operator

• #dilate(*, diagonal : Bool = true) : Mask

  Dilation operator

• #dilate!(*, diagonal : Bool = true) : self

  Dilation operator

• #erode(*, diagonal : Bool = true) : Mask

  Erosion operator

• #erode!(*, diagonal : Bool = true) : Mask

  Erosion operator

• #height : Int32
• #invert

  Return a new Mask that's a copy of this one with all bits inverted.

• #invert!

  Invert all bits in this instance of Mask.

• #opening(*, diagonal : Bool = true) : Mask

  Opening operator

• #opening!(*, diagonal : Bool = true) : Mask

  Opening operator

• #region : Region

  Returns the bounding box of the mask where all true bits are contained.

• #segments(*, diagonal : Bool = true) : Array(Mask)

  Return an array of Masks, each one corresponding to an area of contiguous true bits (identified from flood fills).

• #set(x : Int32, y : Int32, value : Bool) : Bool

  Set the bit for coordinate x and y

• #shape : Tuple(Int32, Int32)

  Returns the dimension of this mask (width x height)

• #size : Int32

  How many bits are stored in this Mask

• #to_gray : GrayscaleImage

  Convert this Mask to a GrayscaleImage, with false bits becoming 0, and true bits becoming 255

• #width : Int32

Constructor Detail

Instance Method Detail