imglib_test

#!/usr/bin/ruby
# Test different image libraries (ImageScience/FreeImage versus MiniMagick/GraphicsMagick)
# usage : imglib_test image_file height width x_offset y_offset cropped_height cropped_width
# outputs the results of the benchmark

usage = "usage : imglib_test image_file height width x_offset y_offset cropped_height cropped_width"

# Make sure we have enough arguments passed to us
exit puts(usage) || 1 unless ARGV.size == 7

# Pull our file from the commandline
@file = ARGV.shift

# detect if file exists, otherwise the scene is going to get nasty
exit puts("File doesn't exist!!").to_i unless File.exist? @file

# Now we save these so we don't have to perform these string operations later
@file_ext = File.extname(@file)
@file_basename = File.basename(@file, @file_ext)

# Assign the rest of our variables
@height, @width, @x_offset, @y_offset, @cropped_height, @cropped_width = *ARGV.map{|a|a.to_i}

# Calculate the two extra variables we need
@x2 = @x_offset + @cropped_width
@y2 = @y_offset + @cropped_height

# ImageScience
require 'image_science'
def img_sci #(height, width, x1, y1, x2, y2)
  ImageScience.with_image(@file) do |image|
    image.resize(@height, @width) do |resized_image|
      resized_image.with_crop(@x_offset, @y_offset, @x2, @y2) do |cropped_image|
        cropped_image.save "#{@file_basename}_img_sci_cropped.#{@file_ext}"
      end
    end
  end
end


# MiniMagick
require 'mini_magick'
MiniMagick.processor = :gm
def min_mag #(height, width, x, y, cropped_height, cropped_width)
  image = MiniMagick::Image.from_file(@file)
  image.combine_options do |cropped_image|
    cropped_image.resize "#{@width}x#{@height}"
    cropped_image.crop "#{@cropped_width}x#{@cropped_height}+#{@x_offset}+#{@y_offset}"
  end
  image.write "#{@file_basename}_min_mag_cropped.#{@file_ext}"
end


# Ruby benchmarks

# Here's the standard benchmark
require 'benchmark'
benchmarky_stuff = Benchmark.bmbm do |image_benchmark|
  image_benchmark.report("Image Science") {img_sci}
  image_benchmark.report("MiniMagick") {min_mag}
end

# repeated iteration test
iterations = 20
deltas = []

# I didn't write this method, but this is the average, not the mean
def mean(ary)
  ary.inject(0) { |sum, i| sum += i }/ary.length.to_f 
end
# Is this broken because of the incorrect mean function?
def std_dev(ary, mean)
  Math.sqrt( (ary.inject(0) { |dev, i| 
                dev += (i - mean) ** 2}/ary.length.to_f) )
end

print "\nRunning repetitive testing. This might take a while"

iterations.times do
  img_sci_result = Benchmark.realtime do
    img_sci
  end
  # cleanup
  min_mag_result = Benchmark.realtime do
    min_mag
  end
  # cleanup
  deltas << (img_sci_result - min_mag_result)

  print '.'
end

deviation = std_dev(deltas, mean(deltas))
mean_delta = mean(deltas) 

printf "\n\nThe deviation in the deltas was %f\n", deviation
printf "The mean delta was %f\n", mean_delta
max = mean_delta + 2.0 * deviation
min = mean_delta - 2.0 * deviation
if min <= 0 || 0 >= max
 puts "There's no statistical difference"
end