FEATURE - ImageMagick jpeg quality (#11004)

* FEATURE - Add SiteSettings to control JPEG image quality

`recompress_original_jpg_quality` - the maximum quality of a newly
uploaded file.

`image_preview_jpg_quality` - the maximum quality of OptimizedImages

app/models/optimized_image.rb

@@ -85,6 +85,9 @@ class OptimizedImage < ActiveRecord::Base
         temp_file = Tempfile.new(["discourse-thumbnail", extension])
         temp_path = temp_file.path
 
+        target_quality = upload.target_image_quality(original_path, SiteSetting.image_preview_jpg_quality)
+        opts = opts.merge(quality: target_quality) if target_quality
+
         if upload.extension == "svg"
           FileUtils.cp(original_path, temp_path)
           resized = true
@@ -218,6 +221,10 @@ class OptimizedImage < ActiveRecord::Base
       instructions << "-colors" << opts[:colors].to_s
     end
 
+    if opts[:quality]
+      instructions << "-quality" << opts[:quality].to_s
+    end
+
     # NOTE: ORDER is important!
     instructions.concat(%W{
       -auto-orient
@@ -228,7 +235,6 @@ class OptimizedImage < ActiveRecord::Base
       -interpolate catrom
       -unsharp 2x0.5+0.7+0
       -interlace none
-      -quality 98
       -profile #{File.join(Rails.root, 'vendor', 'data', 'RT_sRGB.icm')}
       #{to}
     })
@@ -240,7 +246,7 @@ class OptimizedImage < ActiveRecord::Base
     from = prepend_decoder!(from, to, opts)
     to = prepend_decoder!(to, to, opts)
 
-    %W{
+    instructions = %W{
       convert
       #{from}[0]
       -auto-orient
@@ -250,10 +256,14 @@ class OptimizedImage < ActiveRecord::Base
       -crop #{dimensions}+0+0
       -unsharp 2x0.5+0.7+0
       -interlace none
-      -quality 98
       -profile #{File.join(Rails.root, 'vendor', 'data', 'RT_sRGB.icm')}
-      #{to}
     }
+
+    if opts[:quality]
+      instructions << "-quality" << opts[:quality].to_s
+    end
+
+    instructions << to
   end
 
   def self.downsize_instructions(from, to, dimensions, opts = {})

app/models/upload.rb

@@ -269,6 +269,14 @@ class Upload < ActiveRecord::Base
     get_dimension(:thumbnail_height)
   end
 
+  def target_image_quality(local_path, test_quality)
+    @file_quality ||= Discourse::Utils.execute_command("identify", "-format", "%Q", local_path).to_i rescue 0
+
+    if @file_quality == 0 || @file_quality > test_quality
+      test_quality
+    end
+  end
+
   def self.sha1_from_short_path(path)
     if path =~ /(\/uploads\/short-url\/)([a-zA-Z0-9]+)(\..*)?/
       self.sha1_from_base62_encoded($2)

config/locales/server.en.yml

@@ -1758,6 +1758,8 @@ en:
     allow_all_attachments_for_group_messages: "Allow all email attachments for group messages."
 
     png_to_jpg_quality: "Quality of the converted JPG file (1 is lowest quality, 99 is best quality, 100 to disable)."
+    recompress_original_jpg_quality: "Quality of uploaded image files (1 is lowest quality, 99 is best quality, 100 to disable)."
+    image_preview_jpg_quality: "Quality of resized image files (1 is lowest quality, 99 is best quality, 100 to disable)."
 
     allow_staff_to_upload_any_file_in_pm: "Allow staff members to upload any files in PM."
 

config/site_settings.yml

@@ -1339,6 +1339,14 @@ files:
     default: 95
     min: 1
     max: 100
+  recompress_original_jpg_quality:
+    default: 90
+    min: 1
+    max: 100
+  image_preview_jpg_quality:
+    default: 90
+    min: 1
+    max: 100
   allow_staff_to_upload_any_file_in_pm:
     default: true
     client: true

lib/upload_creator.rb

@@ -56,7 +56,7 @@ class UploadCreator
         if @image_info.type.to_s == "svg"
           clean_svg!
         elsif !Rails.env.test? || @opts[:force_optimize]
-          convert_to_jpeg! if convert_png_to_jpeg?
+          convert_to_jpeg! if convert_png_to_jpeg? || should_alter_quality?
           downsize!        if should_downsize?
 
           return @upload   if is_still_too_big?
@@ -202,11 +202,16 @@ class UploadCreator
     from = OptimizedImage.prepend_decoder!(from, nil, filename: "image.#{@image_info.type}")
     to = OptimizedImage.prepend_decoder!(to)
 
+    opts = {}
+    desired_quality = [SiteSetting.png_to_jpg_quality, SiteSetting.recompress_original_jpg_quality].compact.min
+    target_quality = @upload.target_image_quality(from, desired_quality)
+    opts = { quality: target_quality } if target_quality
+
     begin
-      execute_convert(from, to)
+      execute_convert(from, to, opts)
     rescue
       # retry with debugging enabled
-      execute_convert(from, to, true)
+      execute_convert(from, to, opts.merge(debug: true))
     end
 
     new_size = File.size(jpeg_tempfile.path)
@@ -237,7 +242,7 @@ class UploadCreator
       execute_convert(from, to)
     rescue
       # retry with debugging enabled
-      execute_convert(from, to, true)
+      execute_convert(from, to, { debug: true })
     end
 
     @file.respond_to?(:close!) ? @file.close! : @file.close
@@ -245,22 +250,26 @@ class UploadCreator
     extract_image_info!
   end
 
-  def execute_convert(from, to, debug = false)
+  def execute_convert(from, to, opts = {})
     command = [
       "convert",
       from,
       "-auto-orient",
       "-background", "white",
       "-interlace", "none",
-      "-flatten",
+      "-flatten"
-      "-quality", SiteSetting.png_to_jpg_quality.to_s
     ]
-    command << "-debug" << "all" if debug
+    command << "-debug" << "all" if opts[:debug]
+    command << "-quality" << opts[:quality].to_s if opts[:quality]
     command << to
 
     Discourse::Utils.execute_command(*command, failure_message: I18n.t("upload.png_to_jpg_conversion_failure_message"))
   end
 
+  def should_alter_quality?
+    @upload.target_image_quality(@file.path, SiteSetting.recompress_original_jpg_quality).present?
+  end
+
   def should_downsize?
     max_image_size > 0 && filesize >= max_image_size
   end

spec/lib/upload_creator_spec.rb

@@ -123,6 +123,11 @@ RSpec.describe UploadCreator do
     end
 
     describe 'converting to jpeg' do
+      def image_quality(path)
+        local_path = File.join(Rails.root, 'public', path)
+        Discourse::Utils.execute_command("identify", "-format", "%Q", local_path).to_i
+      end
+
       let(:filename) { "should_be_jpeg.png" }
       let(:file) { file_from_fixtures(filename) }
 
@@ -168,6 +173,21 @@ RSpec.describe UploadCreator do
         expect(File.extname(upload.url)).to eq('.jpeg')
         expect(upload.original_filename).to eq('should_be_jpeg.jpg')
       end
+
+      it 'should alter the image quality' do
+        SiteSetting.png_to_jpg_quality = 75
+        SiteSetting.recompress_original_jpg_quality = 40
+        SiteSetting.image_preview_jpg_quality = 10
+
+        upload = UploadCreator.new(file, filename, force_optimize: true).create_for(user.id)
+
+        expect(image_quality(upload.url)).to eq(SiteSetting.recompress_original_jpg_quality)
+
+        upload.create_thumbnail!(100, 100)
+        upload.reload
+
+        expect(image_quality(upload.optimized_images.first.url)).to eq(SiteSetting.image_preview_jpg_quality)
+      end
     end
 
     describe 'converting HEIF to jpeg' do