Revision as of 17:30, 2 October 2007

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Introduction

HornetsEye is a Ruby-extension for real-time computer vision under GNU/Linux offering interfaces to do image- and video-I/O with RMagick, Xine, IIDC/DCAM-compatible firewire digital camera (DC1394) and video for Linux (V4L).

HornetsEye also is an attempt to use the Mimas library and create a minimalistic and consistent real-time computer vision library.

• minimalistic: The library is focused on real-time computer vision. Existing libraries are being made used of.
• consistent:: A non-redundant set of data-types is used. Also the library tries to stay consistent with existing libraries.

The logo was created using GIMP and it shows a honeycomb structure as you would find on an insect's compound eye. A hornet is capable of navigating and detecting objects with the limited resolution of its compound eyes.

Examples

See Hornetseye homepage for more examples.

Simple Webcam Application

The Linux webcam application uses HornetsEye-1.5, RMagick, and qt4-ruby (there also is a Windows webcam already).

You need to install qt4-qtruby-1.4.8 or later because there was a memory leak in Qt::ByteArray of qt4-qtruby-1.4.7. Many thanks to Richard Dale for fixing the problem!

Once the required software is installed, one can develop sophisticated applications within a very short time. As an example here is the source code of the webcam application. Note that you need the user-interface description file as well (which was created with Qt4 designer). You need to compile the user-interface file with rbuic4 to get ui_webcamwindow.rb.

#!/usr/bin/ruby
# Qt webcam (requires Qt4-Ruby)
require 'Qt'
require 'hornetseye'
require 'ui_webcamwindow'
app=Qt::Application.new(ARGV)
class WebcamWindow < Qt::Dialog
  slots 'open_camera()'
  slots 'set_value(int)'
  def initialize( parent = nil )
    super
    @ui = Ui::WebcamWindow.new
    @ui.setupUi( self )
    Qt::Object.connect( @ui.reconnectButton, SIGNAL('clicked()'),
                        self, SLOT('open_camera()'))
    Qt::Object.connect( @ui.brightnessSlider, SIGNAL('valueChanged(int)'),
                        self, SLOT('set_value(int)'))
    Qt::Object.connect( @ui.hueSlider, SIGNAL('valueChanged(int)'),
                        self, SLOT('set_value(int)'))
    Qt::Object.connect( @ui.colourSlider, SIGNAL('valueChanged(int)'),
                        self, SLOT('set_value(int)'))
    Qt::Object.connect( @ui.contrastSlider, SIGNAL('valueChanged(int)'),
                        self, SLOT('set_value(int)'))
    @timer = 0
    open_camera
  end
  def open_camera
    @ui.errorLabel.text = ""
    begin
      @input.close if @input != nil
      @input = nil
      @input = Hornetseye::V4LInput.new( @ui.deviceEdit.text )
      @timer = startTimer( 0 ) if @timer == 0
    rescue RuntimeError => e
      @ui.errorLabel.text = e.to_s
      @input = nil
    end
    @input
  end
  def set_value( value )
    puts "hi"
    @input.set_sensivity( @ui.brightnessSlider.value,
                          @ui.hueSlider.value,
                          @ui.colourSlider.value,
                          @ui.contrastSlider.value ) if @input != nil
  end
  def timerEvent( e )
    begin
      raise "No input available" if @input == nil
      str = @input.read.to_magick.to_blob {
        self.format = "PPM"
        self.depth = 8
      }
      pix = Qt::Pixmap.new
      pix.loadFromData( Qt::ByteArray.fromRawData( str, str.size ) )
      @ui.displayLabel.setPixmap( pix )
      @ui.displayLabel.update
    rescue RuntimeError => e
      killTimer( @timer )
      @timer = 0
    end
  end
end
win = WebcamWindow.new
win.show
app.exec

Also see project documentation.

Phase Correlation

This is an implementation of the phase correlation for aligning images. The code depends on HornetsEye-1.5 and NArray-fftw3.

#!/usr/bin/ruby
require 'hornetseye'
require 'fftw3'
include Hornetseye
syntax = <<END_OF_STRING
Shift estimation
Syntax: registration.rb <image1> <image2>
Example: registration.rb astronaut.jpg apollo-16.jpg
Example: registration.rb apollo_left.jpg apollo_right.jpg
END_OF_STRING
if ARGV.size != 2
  puts syntax
  raise "Wrong number of command-line arguments."
end
image = (0...2).collect { |i| NArray.load_grey8( ARGV[i] ) }
# TODO: Apply windowing function?
# Force images to have same size. Make image twice as big to avoid cyclical
# correlation.
maxwidth  = [ image[0].shape[0], image[1].shape[0] ].max * 2
maxheight = [ image[0].shape[1], image[1].shape[1] ].max * 2
limage = image.collect { |img|
  nimg = NArray.new( NArray::BYTE, maxwidth, maxheight )
  nimg[ 0...img.shape[0], 0...img.shape[1] ] = img
  nimg
}
fimage = limage.collect { |img|
  FFTW3.dft( img.to_type( NArray::DCOMPLEX ), +1 )
}
limage = nil
fshift = ( fimage[0] * fimage[1].conj ) / ( fimage[0].abs * fimage[1].abs )
fimage = nil
# TODO: Replace with native implementation for higher performance.
fshift = fshift.collect { |value|
  if value.real.nan? or value.imag.nan?
    0
  else
    value
  end
}
shift = FFTW3.dft( fshift, -1 )
width  = shift.shape[0]
height = shift.shape[1]
shiftx = nil
shifty = nil
maxvalue = 0
for i in 0...width
  for j in 0...height
    if shift[i,j] > maxvalue
      shiftx = i
      shifty = j
      maxvalue = shift[i,j]
    end
  end
end
shiftx = shiftx - width  if shiftx > width  / 2
shifty = shifty - height if shifty > height / 2
shift = nil
puts "shift-x = #{shiftx}"
puts "shift-y = #{shifty}"
minx = [ 0, shiftx ].min
miny = [ 0, shifty ].min
maxx = [ image[0].shape[0], image[1].shape[0] + shiftx ].max - 1
maxy = [ image[0].shape[1], image[1].shape[1] + shifty ].max - 1
offsetx = -minx
offsety = -miny
resultwidth  = maxx + 1 - minx
resultheight = maxy + 1 - miny
result1 = NArray.new( NArray::BYTE, resultwidth, resultheight )
result1[ offsetx...( offsetx + image[0].shape[0] ),
         offsety...( offsety + image[0].shape[1] ) ] = image[0] / 2
result2 = NArray.new( NArray::BYTE, resultwidth, resultheight )
result2[ ( shiftx + offsetx )...( shiftx + offsetx + image[1].shape[0] ),
         ( shifty + offsety )...( shifty + offsety + image[1].shape[1] ) ] = image[1] / 2
result = result1 + result2
result.display

Downloads

Before downloading you may want to check the installation instructions for information on what other software you need to install and run Hornetseye. See download instructions on how to obtain Hornetseye.

Software Engineering

HornetsEye brings the functionality of existing powerful free software packages into Ruby. HornetsEye also tries to make existing Ruby extension operate with each other to enable the development of novel solutions:

1. QtRuby, Korundum: QtRuby and Korundum can be used to develop graphical user interfaces and desktop applications.
2. Xine: Using Xine one can read virtually any video file and it is even possible to read streaming videos.
3. NArray: Masahiro Tanaka's NArray is an implementation of n-dimensional arrays for Ruby.
4. FFTW. The fftw-library can is maybe the fastest library for performing discrete Fourier transforms. It can be invoked by using Masahiro Tanaka's fftw3 extension.
5. RMagick: The RMagick Ruby-extension allows to use the powerful Magick++ library in Ruby for loading and saving images.
6. libdc1394: Using libdc1394 one can make use of a large choice of firewire digital cameras.
7. OpenEXR: The OpenEXR library is used for saving and loading high dynamic range images.
8. Boost: The Boost Library offers smart pointers to do exception safe programming, multi-dimensional arrays, template meta-programming, abstract data types for linear algebra and many other programming concepts. The Boost library is going to be part of a future C++ standard.
9. STL: The software makes use of the Standard Template Library
10. Ruby programming language
11. gnu-arch: gnu-arch is being used for version control.
12. Gcc: gcc is the C++ compiler of the GNU project.
13. autoconf, automake and make: make, autoconf and automake are used to configure and perform the build of the software on various distributions of the Linux operating system.
14. Natural Docs: Natural Docs is used to create the HTML documentation.

See Also

• Mimas
• Computer Vision Software
• Hypercomplex Wavelets

External Links

• Hornetseye homepage
• Hornetseye at Rubyforge
• Hornetseye at Sourceforge
• SWIG (Simplified Wrapper and Interface Generator)
• Moments in image processing