Add convert_options to attachment definition and thumbnail's transformation command line.

lib/paperclip/attachment.rb

@@ -34,6 +34,7 @@ module Paperclip
       @default_style     = options[:default_style]
       @storage           = options[:storage]
       @whiny_thumbnails  = options[:whiny_thumbnails]
+      @convert_options   = options[:thumbnail_convert_options]
       @options           = options
       @queued_for_delete = []
       @queued_for_write  = {}
@@ -241,7 +242,8 @@ module Paperclip
           @queued_for_write[name] = Thumbnail.make(@queued_for_write[:original], 
                                                    dimensions,
                                                    format, 
-                                                   @whiny_thumnails)
+                                                   @whiny_thumnails,
+                                                   @convert_options)
         rescue PaperclipError => e
           @errors << e.message if @whiny_thumbnails
         end

lib/paperclip/thumbnail.rb

@@ -2,19 +2,21 @@ module Paperclip
   # Handles thumbnailing images that are uploaded.
   class Thumbnail
 
-    attr_accessor :file, :current_geometry, :target_geometry, :format, :whiny_thumbnails
+    attr_accessor :file, :current_geometry, :target_geometry, :format, :whiny_thumbnails, :convert_options
 
     # Creates a Thumbnail object set to work on the +file+ given. It
     # will attempt to transform the image into one defined by +target_geometry+
     # which is a "WxH"-style string. +format+ will be inferred from the +file+
     # unless specified. Thumbnail creation will raise no errors unless
-    # +whiny_thumbnails+ is true (which it is, by default.
-    def initialize file, target_geometry, format = nil, whiny_thumbnails = true
+    # +whiny_thumbnails+ is true (which it is, by default. If +convert_options+ is
+    # set, the options will be appended to the convert command upon image conversion 
+    def initialize file, target_geometry, format = nil, whiny_thumbnails = true, convert_options = nil
       @file             = file
       @crop             = target_geometry[-1,1] == '#'
       @target_geometry  = Geometry.parse target_geometry
       @current_geometry = Geometry.from_file file
       @whiny_thumbnails = whiny_thumbnails
+      @convert_options  = convert_options
 
       @current_format   = File.extname(@file.path)
       @basename         = File.basename(@file.path, @current_format)
@@ -24,14 +26,19 @@ module Paperclip
 
     # Creates a thumbnail, as specified in +initialize+, +make+s it, and returns the
     # resulting Tempfile.
-    def self.make file, dimensions, format = nil, whiny_thumbnails = true
-      new(file, dimensions, format, whiny_thumbnails).make
+    def self.make file, dimensions, format = nil, whiny_thumbnails = true, convert_options = nil
+      new(file, dimensions, format, whiny_thumbnails, convert_options).make
     end
 
     # Returns true if the +target_geometry+ is meant to crop.
     def crop?
       @crop
     end
+    
+    # Returns true if the image is meant to make use of additional convert options.
+    def convert_options?
+      @convert_options
+    end
 
     # Performs the conversion of the +file+ into a thumbnail. Returns the Tempfile
     # that contains the new image.
@@ -61,6 +68,7 @@ module Paperclip
       scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
       trans = "-scale \"#{scale}\""
       trans << " -crop \"#{crop}\" +repage" if crop
+      trans << " #{convert_options}" if convert_options?
       trans
     end
   end