module

CrImage::Util::PixelIterator

Pixel iteration utilities for functional-style image processing.

Provides high-level iteration methods for transforming images pixel-by-pixel using blocks/closures. Useful for custom color transformations and filters.

Class methods

each_pixel(src : Image, &block : Int32, Int32, UInt32, UInt32, UInt32, UInt32 -> Nil)

Iterates over each pixel with coordinates and color values.

Calls the block for every pixel, passing both position (x, y) and 32-bit color values (r, g, b, a). Useful for analysis and statistics.

Parameters:

src : The source image
block : Iteration function (x, y, r, g, b, a) -> Nil

Returns: Nothing (side effects only)

Example:

# Count bright pixels
bright_count = 0
CrImage::Util::PixelIterator.each_pixel(img) do |x, y, r, g, b, a|
  luminance = (r * 299 + g * 587 + b * 114) // 1000
  bright_count += 1 if luminance &gt; 32768
end

Source

map_pixels(src : Image, &block : UInt32, UInt32, UInt32, UInt32 -> Color::Color) : Image

Maps each pixel through a transformation function.

Applies the given block to every pixel in the image, where the block receives 32-bit RGBA values and returns a new color.

Parameters:

src : The source image
block : Transformation function (r, g, b, a) -> Color

Returns: A new RGBA image with transformed pixels

Example:

# Invert colors
inverted = CrImage::Util::PixelIterator.map_pixels(img) do |r, g, b, a|
  CrImage::Color.rgba(
    (65535 - r).to_u8,
    (65535 - g).to_u8,
    (65535 - b).to_u8,
    a &gt;&gt; 8
  )
end

Source

map_pixels_8bit(src : Image, &block : UInt8, UInt8, UInt8, UInt8 -> Color::RGBA) : Image

Maps each pixel through a transformation function using 8-bit values.

Convenience method that converts 32-bit color values to 8-bit (0-255) before passing to the block. Simpler for most use cases.

Parameters:

src : The source image
block : Transformation function (r, g, b, a) -> Color::RGBA

Returns: A new RGBA image with transformed pixels

Example:

# Increase brightness
brighter = CrImage::Util::PixelIterator.map_pixels_8bit(img) do |r, g, b, a|
  CrImage::Color::RGBA.new(
    (r + 50).clamp(0, 255).to_u8,
    (g + 50).clamp(0, 255).to_u8,
    (b + 50).clamp(0, 255).to_u8,
    a
  )
end

Source