PureImage

PureImage is a raster image processing library written in Scala. See slides at [http://stephenjudkins.github.io/pureimage-presentation/]

Motivation

Available image processing and manipulation libraries are difficult to use. They feature byzantive and opaque APIs. [http://docs.oracle.com/javase/7/docs/api/java/awt/image/BufferedImage.html] Or, they require concrete in-memory representations of pixel data in order to perform manipulations. [http://www.imagemagick.org/script/magick-core.php]

However, images are simple things. We aim to provide a set of tools that operate on a single simple abstraction.

API

trait Image[A] {
  def width: Int
  def height: Int
  def apply(x: Int, y: Int):A
}

Further, we aim to support image input in a similarly simple manner:

sealed trait LoadedImage
case class RGBImage(image: Image[RGB]) extends LoadedImage
case class RGBAImage(image: Image[RGBA]) extends LoadedImage
case class GrayImage(image: Image[Gray]) extends LoadedImage

sealed trait ReadError
case object UnsupportedImageType extends ReadError
case class ReadException(e: Exception) extends ReadError

object Input {
  def apply(data: Array[Byte]):Either[ReadError, LoadedImage] = ???
}

Output, which may require us to deal with arbitrary output formats and pixel types, sees utility from applying type classes [http://en.wikipedia.org/wiki/Type_class ]:

trait Output[I, O <: OutputFormat] {
  def apply(i: Image[I], o: O):Array[Byte]
}

object Output {
  def apply[I, O <: OutputFormat](image: Image[I], format: O)(implicit output: Output[I,O]) = ???
}

Likewise, we support common operations on pixel types, both included and user-defined, using type classes:

trait Pixel[A] {
  def sum(a: A, b: A):A
  def fade(p: A, f: Float):A
  def zero: A
}

Included pixel types in include RGB, RGBA, and grayscale. All are represented internally as 32-bit integers. Once certain Scala issues are addressed [https://issues.scala-lang.org/browse/SI-5611] specialization should give us fast performance. Currently these representations are boxed at runtime, but performance should be reasonably good for many use cases.

Getting PureImage

Add the following to your build.sbt:

resolvers += "stephenjudkins-bintray" at "http://dl.bintray.com/stephenjudkins/maven"

libraryDependencies += "ps.tricerato" %% "pureimage" % "0.1.2"