diff --git a/Gemfile b/Gemfile
index 563e95f..46a4f91 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,4 @@
 source 'https://rubygems.org'
 
 gemspec
-# For test OCR
-gem 'rtesseract'
 gem 'mini_magick'
diff --git a/Gemfile.lock b/Gemfile.lock
index f5f7a04..daad2dd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -102,8 +102,6 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.3.0)
     rspec-support (3.3.0)
-    rtesseract (1.3.1)
-      nokogiri
     sprockets (3.3.5)
       rack (> 1, < 3)
     sprockets-rails (2.3.3)
@@ -123,7 +121,6 @@ DEPENDENCIES
   rails
   rake
   rspec (>= 3.3.0)
-  rtesseract
   rucaptcha!
 
 BUNDLED WITH
diff --git a/lib/rucaptcha.rb b/lib/rucaptcha.rb
index 8275aae..c139f84 100644
--- a/lib/rucaptcha.rb
+++ b/lib/rucaptcha.rb
@@ -26,14 +26,6 @@ module RuCaptcha
     def configure(&block)
       config.instance_exec(&block)
 
-      if config.width != nil
-        ActiveSupport::Deprecation.warn("RuCaptcha config.width will remove in 0.4.0")
-      end
-
-      if config.height != nil
-        ActiveSupport::Deprecation.warn("RuCaptcha config.height will remove in 0.4.0")
-      end
-
       # enable cache if cache_limit less than 1
       if config.cache_limit >= 1
         RuCaptcha::Captcha.send(:include, RuCaptcha::Cache)
diff --git a/lib/rucaptcha/captcha.rb b/lib/rucaptcha/captcha.rb
index 88aa1c8..602c653 100644
--- a/lib/rucaptcha/captcha.rb
+++ b/lib/rucaptcha/captcha.rb
@@ -5,7 +5,10 @@ module RuCaptcha
     class << self
       def random_color
         if RuCaptcha.config.style == :colorful
-          [rand(100).to_s(8), rand(100).to_s(8), rand(100).to_s(8)]
+          color_seed = (rand(150) + 40).to_s(8)
+          color = [0.to_s(8), 0.to_s(8), 0.to_s(8)]
+          color[rand(3)] = color_seed
+          color
         else
           color_seed = rand(50).to_s(8)
           [color_seed, color_seed, color_seed]
@@ -35,7 +38,7 @@ module RuCaptcha
         half_height  = full_height / 2
         text_top     = 0
         text_left    = 0 - (font_size * 0.28).to_i
-        stroke_width  = (font_size * 0.08).to_i + 1
+        stroke_width  = (font_size * 0.05).to_i + 1
         text_width   = font_size + text_left
         label = "=#{' ' * (chars.size - 1)}="
 
@@ -58,7 +61,7 @@ module RuCaptcha
           #{line_opts.join(' ')} \
           -pointsize #{font_size} -weight 500 \
           #{text_opts.join(' ')}  \
-          -wave #{rand(2) + 3}x#{rand(2) + 1} \
+          -wave #{rand(2) + 1}x#{rand(2) + 1} \
           -rotate #{rand(10) - 5} \
           -gravity NorthWest -sketch 1x10+#{rand(2)} \
           -fill none \
diff --git a/spec/controller_helpers_spec.rb b/spec/controller_helpers_spec.rb
index f1fc08b..34a1e5a 100644
--- a/spec/controller_helpers_spec.rb
+++ b/spec/controller_helpers_spec.rb
@@ -41,6 +41,7 @@ describe RuCaptcha do
         simple.session[:_rucaptcha] = 'abcd'
         simple.params[:_rucaptcha] = 'Abcd'
         expect(simple.verify_rucaptcha?).to eq(true)
+        simple.session[:_rucaptcha] = 'abcd'
         simple.params[:_rucaptcha] = 'AbcD'
         expect(simple.verify_rucaptcha?).to eq(true)
       end
diff --git a/spec/ocr_spec.rb b/spec/ocr_spec.rb
deleted file mode 100644
index 30e9bc2..0000000
--- a/spec/ocr_spec.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require 'spec_helper'
-require 'fileutils'
-require 'tmpdir'
-
-describe 'OCR' do
-  before do
-    @tmp_dir = Dir.mktmpdir
-    @samples = []
-    10.times do
-      @samples << SecureRandom.hex(2)
-    end
-    @filenames = []
-    @samples.each do |chars|
-      fname = File.join(@tmp_dir, "#{chars}.png")
-      img = RuCaptcha::Captcha.create(chars)
-      File.open(fname, 'w+') do |f|
-        f.puts img
-      end
-      @filenames << fname
-    end
-  end
-
-  after do
-    FileUtils.rm_f(@tmp_dir)
-  end
-
-  it 'should not read by OCR lib' do
-    results = []
-    @samples.each do |chars|
-      str = RTesseract.new(File.join(@tmp_dir, "#{chars}.png"), processor: 'mini_magick').to_s
-      results << "- Chars: #{chars}, OCR read #{str.strip}"
-      expect(chars).not_to eq(str)
-    end
-
-    puts %(\n------------------------\nOCR all results: \n#{results.join("\n")})
-  end
-end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index eebdc01..553994d 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -4,7 +4,6 @@ $LOAD_PATH.unshift(File.dirname(__FILE__))
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 
 require 'rucaptcha'
-require 'rtesseract'
 
 tmp_path = File.join(File.dirname(__FILE__), '../tmp')
 if !File.exists?(tmp_path)
@@ -21,7 +20,6 @@ end
 
 RuCaptcha.configure do
   self.len = 2
-  self.height = 33
   self.font_size = 48
   self.implode = 0.111
 end