Crate image_pyramid

Image Pyramid

Overview

This is a small Rust crate that facilitates quickly generating an image pyramid from a user-provided image.

• See OpenCV: Image Pyramids for an overview of the two most common pyramid types, Lowpass (AKA Gaussian) and Bandpass (AKA Laplacian).
• The Tomasi paper Lowpass and Bandpass Pyramids has an authoritative explanation as well.
• Wikipedia has a decent explanation of a steerable pyramid

Usage

See the crates.io page for installation instructions, then check out the examples directory for example code. Below is a simple illustrative example of computing a default pyramid (Gaussian where each level is half resolution).

use image::DynamicImage;
use image_pyramid::*;

let image = DynamicImage::new_rgba8(640, 480); // Or load from file
let pyramid = match ImagePyramid::create(&image, None) {
  Ok(pyramid) => pyramid,
  Err(e) => {
    eprintln!("Error creating image pyramid: {}", e);
    return;
  }
};

Or a slightly more complex example, illustrating how to create a bandpass pyramid where each octave is 2/3 the resolution, smoothed using a triangle (linear) filter.

use image::DynamicImage;
use image_pyramid::*;

let image = DynamicImage::new_rgba8(640, 480); // Or load from file
let params = ImagePyramidParams {
  scale_factor:   (2.0 / 3.0).into_unit_interval().unwrap(),
  pyramid_type:   ImagePyramidType::Bandpass,
  smoothing_type: SmoothingType::Triangle,
};
let pyramid = match ImagePyramid::create(&image, Some(&params)) {
  Ok(pyramid) => pyramid,
  Err(e) => {
    eprintln!("Error creating image pyramid: {}", e);
    return;
  }
};

ImagePyramidParams::scale_factor field is a UnitIntervalValue, which must be a floating-point value in the interval (0, 1). Creating a value of this type yields a Result and will contain an error if the value is not valid.

Support

Open an Issue with questions or bug reports, and feel free to open a PR with proposed changes.

Contributing

Follow standard Rust conventions, and be sure to add tests for any new code added.

Structs

ImagePyramid

A computed image pyramid and its associated metadata.

ImagePyramidParams

The set of parameters required for computing an image pyramid. For most applications, the default set of parameters is correct.

ImageToProcess

A simple wrapper extending the functionality of the given image with image-pyramid support

UnitIntervalValue

A container for a value falling on the range (0.0, 1.0) (exclusive, meaning the values 0.0 and 1.0 are not valid)

Enums

ImagePyramidError

An enumeration of the errors that may be emitted from the image_pyramid crate

ImagePyramidType

What type of pyramid to compute. Each has different properties, applications, and computation cost.

SmoothingType

How to smooth an image when downsampling

Traits

CanComputePyramid

Describes types that can compute their own image pyramid

IntoUnitInterval

A trait describing some floating-point type that can be converted to a unit-interval value (0.0 to 1.0, exclusive)