SSCMEx.Image (sscmex v0.3.5)

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Image structure used by camera capture and model inference.

This is a zero-copy wrapper over an Elixir binary. The data field holds a reference to the original binary.

Supported Formats

Raw (fixed bytes-per-pixel):

  • :rgb888
  • :rgb888_planar
  • :rgb565
  • :yuv422
  • :gray

Encoded (variable size):

  • :jpeg
  • :h264
  • :h265

Example

# Create image from camera frame (zero-copy)
frame = capture_camera_frame()  # Returns binary
image = SSCMEx.Image.new(640, 480, :rgb888, frame)

# Run inference
{:ok, results} = SSCMEx.Model.run(model, image)

Summary

Types

convert_format()

Supported pixel formats for convert operations. Note: YUV422 can only be used as input (YUV422→RGB/Grayscale), not as output (RGB→YUV422 is not supported by OpenCV 3.2.0).

encoded_format()
format()
interpolation()

Interpolation methods for resize operations.

raw_format()
t()

Functions

convert(image, format, opts \\ [])

Convert image to a different format.

data_size(image)

Returns the expected byte size for the image data based on dimensions and format.

new(width, height, format, data)

Create a new image struct.

resize(image, arg, opts \\ [])

Resize image to new dimensions.

valid?(image)

Validates that the image data size matches the expected size for the given dimensions and format.

Types

convert_format()

@type convert_format() :: :rgb888 | :rgb565 | :yuv422 | :gray | :jpeg | :webp

Supported pixel formats for convert operations. Note: YUV422 can only be used as input (YUV422→RGB/Grayscale), not as output (RGB→YUV422 is not supported by OpenCV 3.2.0).

encoded_format()

@type encoded_format() :: :jpeg | :h264 | :h265

format()

@type format() :: raw_format() | encoded_format()

interpolation()

@type interpolation() :: :nearest | :bilinear | :bicubic | :area | :lanczos4

Interpolation methods for resize operations.

raw_format()

@type raw_format() :: :rgb888 | :rgb888_planar | :rgb565 | :yuv422 | :gray

t()

@type t() :: %SSCMEx.Image{
  data: binary(),
  format: format(),
  height: non_neg_integer(),
  key: boolean() | nil,
  size: non_neg_integer() | nil,
  timestamp: integer() | nil,
  width: non_neg_integer()
}

Functions

convert(image, format, opts \\ [])

@spec convert(t(), convert_format(), keyword()) :: {:ok, t()} | {:error, atom()}

Convert image to a different format.

Supported conversions

Raw formats (RGB888, RGB565, YUV422, Grayscale):

  • RGB888 ↔ Grayscale
  • RGB888 ↔ RGB565
  • YUV422 → RGB888/Grayscale (note: reverse not supported)

Compressed formats:

  • Any raw format → JPEG
  • Any raw format → WebP (requires libwebp support in SDK)

Options

  • :quality - JPEG/WebP quality 0-100 (default: 85)

Examples

{:ok, webp} = SSCMEx.Image.convert(image, :webp, quality: 90)
{:ok, gray} = SSCMEx.Image.convert(image, :gray)
{:ok, rgb} = SSCMEx.Image.convert(yuv_image, :rgb888)

data_size(image)

@spec data_size(t()) :: non_neg_integer()

Returns the expected byte size for the image data based on dimensions and format.

Example

iex> SSCMEx.Image.data_size(%SSCMEx.Image{width: 640, height: 480, format: :rgb888, data: <<>>})
921600

new(width, height, format, data)

@spec new(non_neg_integer(), non_neg_integer(), format(), binary()) :: t()

Create a new image struct.

This is zero-copy - data binary is referenced, not copied.

Parameters

  • width - Image width in pixels
  • height - Image height in pixels
  • format - Pixel format
  • data - Binary image data (not copied)

Example

image = SSCMEx.Image.new(640, 480, :rgb888, frame_data)

resize(image, arg, opts \\ [])

@spec resize(t(), {pos_integer(), pos_integer()}, keyword()) ::
  {:ok, t()} | {:error, atom()}

Resize image to new dimensions.

Options

  • :interpolation - :nearest, :bilinear (default), :bicubic, :area, :lanczos4

Examples

{:ok, small} = SSCMEx.Image.resize(image, {320, 240})
{:ok, thumb} = SSCMEx.Image.resize(image, {160, 120}, interpolation: :lanczos4)

valid?(image)

@spec valid?(t()) :: boolean()

Validates that the image data size matches the expected size for the given dimensions and format.

Example

iex> image = SSCMEx.Image.new(2, 2, :rgb888, <<255, 0, 0, 0, 255, 0, 0, 0, 255, 255, 255, 255>>)
iex> SSCMEx.Image.valid?(image)
true