diff --git a/Gemfile b/Gemfile
index 90735174..19c81d1e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,6 +20,7 @@
 source 'https://rubygems.org' do
   gem 'active_record_union'
   gem 'activestorage'
+  gem 'image_processing', '~> 1.2'
   gem 'ox' # Dav4Rack
   gem 'rake' unless Dir.exist?(File.expand_path('../../redmine_dashboard', __FILE__))
   gem 'simple_enum'
diff --git a/app/controllers/dmsf_files_controller.rb b/app/controllers/dmsf_files_controller.rb
index d75689ac..2d72c16d 100644
--- a/app/controllers/dmsf_files_controller.rb
+++ b/app/controllers/dmsf_files_controller.rb
@@ -322,20 +322,6 @@ class DmsfFilesController < ApplicationController
     redirect_to trash_dmsf_path(@project)
   end
 
-  def thumbnail
-    tbnail = @file.thumbnail(size: params[:size])
-    if tbnail
-      if stale?(etag: tbnail)
-        send_file tbnail,
-                  filename: filename_for_content_disposition(@file.name),
-                  type: @file.last_revision.content_type,
-                  disposition: 'inline'
-      end
-    else
-      head :not_found
-    end
-  end
-
   private
 
   def find_file
diff --git a/app/helpers/dmsf_helper.rb b/app/helpers/dmsf_helper.rb
index bd306c62..ce5d0070 100644
--- a/app/helpers/dmsf_helper.rb
+++ b/app/helpers/dmsf_helper.rb
@@ -34,7 +34,7 @@ module DmsfHelper
   def self.sanitize_filename(filename)
     # Get only the filename, not the whole path
     just_filename = File.basename(filename.gsub('\\\\', '/'))
-    # Replace all non alphanumeric, hyphens or periods with underscore
+    # Replace all non-alphanumeric, hyphens or periods with underscore
     just_filename.gsub!(/[^\w.\-]/, '_')
     # Keep the extension if any
     if !/^[a-zA-Z0-9_.\-]*$/.match?(just_filename) && just_filename =~ /(.[a-zA-Z0-9]+)$/
diff --git a/app/models/dmsf_file.rb b/app/models/dmsf_file.rb
index 28fedc85..e5ccd629 100644
--- a/app/models/dmsf_file.rb
+++ b/app/models/dmsf_file.rb
@@ -546,7 +546,7 @@ class DmsfFile < ApplicationRecord
   end
 
   def thumbnailable?
-    Redmine::Thumbnail.convert_available? && (image? || (pdf? && Redmine::Thumbnail.gs_available?))
+    last_revision.file&.variable?
   end
 
   def previewable?
@@ -632,29 +632,6 @@ class DmsfFile < ApplicationRecord
     nil
   end
 
-  def thumbnail(options = {})
-    size = options[:size].to_i
-    if size.positive?
-      # Limit the number of thumbnails per image
-      size = (size / 50) * 50
-      # Maximum thumbnail size
-      size = 800 if size > 800
-    else
-      size = Setting.thumbnails_size.to_i
-    end
-    size = 100 unless size.positive?
-    target = File.join(Attachment.thumbnails_storage_path, "#{id}_#{last_revision.digest}_#{size}.thumb")
-    begin
-      Redmine::Thumbnail.generate last_revision.file.download, target, size, pdf?
-    rescue StandardError => e
-      Rails.logger.error do
-        %(An error occured while generating thumbnail for #{last_revision.file&.blob&.filename} to #{target}\n
-          Exception was: #{e.message})
-      end
-      nil
-    end
-  end
-
   def locked_title
     if locked_for_user?
       return l(:title_locked_by_user, user: lock.reverse[0].user) if lock.reverse[0].user
diff --git a/app/views/dmsf_files/_thumbnails.html.erb b/app/views/dmsf_files/_thumbnails.html.erb
index 3ffb90c9..d8aa7a58 100644
--- a/app/views/dmsf_files/_thumbnails.html.erb
+++ b/app/views/dmsf_files/_thumbnails.html.erb
@@ -25,12 +25,20 @@
           <div class="thumbnails">
         <% end %>
           <% images.each do |file| %>
-              <div>
+              <div class="thumbnail" title="<%= file.name %>">
                 <% if link_to # Redmine classic %>
-                    <%= link_to image_tag(dmsf_thumbnail_path(file), alt: file.title), view_dmsf_file_url(file) %>
+                  <% size = Setting.thumbnails_size.to_i %>
+                  <%= link_to image_tag(file.last_revision&.file&.variant(resize_to_limit: [size, size]),
+                                        alt: file.title,
+                                        style: "max-width: #{size}px; max-height: #{size}px;",
+                                        loading: 'lazy'),
+                              view_dmsf_file_url(file) %>
                 <% else # jQuery gallery %>
-                    <%= image_tag(dmsf_thumbnail_path(file),
-                      { :'data-fullsrc' => view_dmsf_file_url(file), alt: file.title }) %>
+                  <%= image_tag(file.last_revision&.file&.variant(resize_to_limit: [size, size]),
+                                :'data-fullsrc' => view_dmsf_file_url(file),
+                                alt: file.title,
+                                style: "max-width: #{size}px; max-height: #{size}px;",
+                                loading: 'lazy') %>
                 <% end %>
               </div>
           <% end %>
diff --git a/lib/redmine_dmsf/macros.rb b/lib/redmine_dmsf/macros.rb
index 391713d4..7b0ce1ca 100644
--- a/lib/redmine_dmsf/macros.rb
+++ b/lib/redmine_dmsf/macros.rb
@@ -241,16 +241,22 @@ module RedmineDmsf
                  {{dmsftn(file_id)}} -- with default height 200 (auto width)
                  {{dmsftn(file_id1 file_id2 file_id3)}} -- multiple thumbnails
                  {{dmsftn(file_id, size=300)}} -- with size 300x300
-                 {{dmsftn(file_id, height=300)}} -- with height (auto width)
-                 {{dmsftn(file_id, width=300)}} -- with width (auto height)
+                 {{dmsftn(file_id, height=300)}} -- with height (default width)
+                 {{dmsftn(file_id, width=300)}} -- with width (default height)
                  {{dmsftn(file_id, size=640x480)}} -- with size 640x480}
       macro :dmsftn do |_obj, args|
         raise ArgumentError if args.empty? # Requires file id
 
         args, options = extract_macro_options(args, :size, :width, :height, :title)
-        size = options[:size]
-        width = options[:width]
-        height = options[:height]
+
+        if options[:size].present?
+          width, height = options[:size].split('x')
+          height = width if height.blank?
+        else
+          width = options[:width].presence || Setting.thumbnails_size.to_i
+          height = options[:height].presence || Setting.thumbnails_size.to_i
+        end
+
         ids = args[0].split
         html = []
         ids.each do |id|
@@ -260,21 +266,17 @@ module RedmineDmsf
             next
           end
           raise ::I18n.t(:notice_not_authorized) unless User.current&.allowed_to?(:view_dmsf_files, file.project)
-          raise ::I18n.t(:error_not_supported_image_format) unless file.image?
+          raise ::I18n.t(:error_not_supported_image_format) unless file&.thumbnailable?
 
           member = Member.find_by(user_id: User.current.id, project_id: file.project.id)
           filename = file.last_revision.formatted_name(member)
           url = static_dmsf_file_url(file, filename: filename)
-          img = if size
-                  image_tag(url, alt: filename, title: file.title, size: size)
-                elsif height
-                  image_tag(url, alt: filename, title: file.title, width: 'auto', height: height)
-                elsif width
-                  image_tag(url, alt: filename, title: file.title, width: width, height: 'auto')
-                else
-                  image_tag(url, alt: filename, title: file.title, width: 'auto', height: 200)
-                end
-          html << link_to(img, url,
+          img = image_tag(file.last_revision&.file&.variant(resize_to_limit: [width, height]),
+                          alt: filename,
+                          style: "max-width: #{width}px; max-height: #{height}px;",
+                          loading: 'lazy')
+          html << link_to(img,
+                          url,
                           target: '_blank',
                           rel: 'noopener',
                           title: h(file.last_revision.try(:tooltip)),
diff --git a/test/unit/lib/redmine_dmsf/dmsf_macros_test.rb b/test/unit/lib/redmine_dmsf/dmsf_macros_test.rb
index 63fed933..aa89d51a 100644
--- a/test/unit/lib/redmine_dmsf/dmsf_macros_test.rb
+++ b/test/unit/lib/redmine_dmsf/dmsf_macros_test.rb
@@ -254,21 +254,23 @@ class DmsfMacrosTest < RedmineDmsf::Test::HelperTest
     size = '50%'
     url = static_dmsf_file_url(@file7, @file7.last_revision.name)
     text = textilizable("{{dmsf_image(#{@file7.id}, size=#{size})}}")
-    assert text.include?(image_tag(url, alt: @file7.name, title: @file7.title, width: size, height: size)), text
-    # TODO: arguments src and with and height are swapped
+    assert_equal "<p>#{image_tag(url, alt: @file7.name, title: @file7.title, width: size, height: size)}</p>", text
+    # TODO: Swaped parameters src and size
     # size = '300'
     # text = textilizable("{{dmsf_image(#{@file7.id}, size=#{size})}}")
-    # assert text.include?(image_tag(url, alt: @file7.name, title: @file7.title, width: size, height: size)), text
-    # TODO: arguments src and with and height are swapped
+    # assert_equal "<p>#{image_tag(url, alt: @file7.name, title: @file7.title, width: size, height: size)}</p>", text
     # size = '640x480'
     # text = textilizable("{{dmsf_image(#{@file7.id}, size=#{size})}}")
-    # assert text.include?(image_tag(url, alt: @file7.name, title: @file7.title, width: '640', height: '480')), text
+    # assert_equal "<p>#{image_tag(url, alt: @file7.name, title: @file7.title, width: '640', height: '480')}</p>",
+    #              text
     height = '480'
     text = textilizable("{{dmsf_image(#{@file7.id}, height=#{height})}}")
-    assert text.include?(image_tag(url, alt: @file7.name, title: @file7.title, width: 'auto', height: height)), text
+    assert_equal "<p>#{image_tag(url, alt: @file7.name, title: @file7.title, width: 'auto', height: height)}</p>",
+                 text
     width = '480'
     text = textilizable("{{dmsf_image(#{@file7.id}, width=#{height})}}")
-    assert text.include?(image_tag(url, alt: @file7.name, title: @file7.title, width: width, height: 'auto')), text
+    assert_equal "<p>#{image_tag(url, alt: @file7.name, title: @file7.title, width: width, height: 'auto')}</p>",
+                 text
   end
 
   def test_macro_dmsf_image_no_permissions
@@ -344,74 +346,86 @@ class DmsfMacrosTest < RedmineDmsf::Test::HelperTest
   def test_macro_dmsftn
     text = textilizable("{{dmsftn(#{@file7.id})}}")
     url = static_dmsf_file_url(@file7, @file7.last_revision.name)
-    img = image_tag(url, alt: @file7.name, title: @file7.title, width: 'auto', height: 200)
+    size = Setting.thumbnails_size.to_i
+    img = image_tag(@file7.last_revision&.file&.variant(resize_to_limit: [size, size]),
+                    alt: @file7.name,
+                    style: "max-width: #{size}px; max-height: #{size}px;",
+                    loading: 'lazy')
     link = link_to(img,
                    url,
                    target: '_blank',
                    rel: 'noopener',
                    title: h(@file7.last_revision.try(:tooltip)),
                    'data-downloadurl' => "#{@file7.last_revision.content_type}:#{h(@file7.name)}:#{url}")
-    assert text.include?(link), text
+    assert_equal "<p>#{link}</p>", text
   end
 
   # {{dmsftn(file_id file_id)}}
   def test_macro_dmsftn_multiple
     text = textilizable("{{dmsftn(#{@file7.id} #{@file7.id})}}")
     url = static_dmsf_file_url(@file7, @file7.last_revision.name)
-    img = image_tag(url, alt: @file7.name, title: @file7.title, width: 'auto', height: 200)
+    img = image_tag(@file7.last_revision&.file&.variant(resize_to_limit: [100, 100]),
+                    alt: @file7.name,
+                    style: 'max-width: 100px; max-height: 100px;',
+                    loading: 'lazy')
     link = link_to(img,
                    url,
                    target: '_blank',
                    rel: 'noopener',
                    title: h(@file7.last_revision.try(:tooltip)),
                    'data-downloadurl': 'image/gif:test.gif:http://www.example.com/dmsf/files/7/test.gif')
-    assert text.include?(link + link), text
+    assert_equal "<p>#{link}#{link}</p>", text
   end
 
   # {{dmsftn(file_id size=300)}}
   def test_macro_dmsftn_size
     url = static_dmsf_file_url(@file7, @file7.last_revision.name)
-    size = '300'
-    text = textilizable("{{dmsftn(#{@file7.id}, size=#{size})}}")
-    img = image_tag(url, alt: @file7.name, title: @file7.title, size: size)
+    size = Setting.thumbnails_size.to_i
+
+    # Size
+    text = textilizable("{{dmsftn(#{@file7.id}, size=300)}}")
+    img = image_tag(@file7.last_revision&.file&.variant(resize_to_limit: [300, 300]),
+                    alt: @file7.name,
+                    style: 'max-width: 300px; max-height: 300px;',
+                    loading: 'lazy')
     link = link_to(img,
                    url,
                    target: '_blank',
                    rel: 'noopener',
                    title: h(@file7.last_revision.try(:tooltip)),
                    'data-downloadurl' => "#{@file7.last_revision.content_type}:#{h(@file7.name)}:#{url}")
-    assert text.include?(link), text
-    # TODO: arguments src and with and height are swapped
-    # size = '640x480'
-    # text = textilizable("{{dmsftn(#{@file7.id}, size=#{size})}}")
-    # img = image_tag(url, alt: @file7.name, title: @file7.title, width: 640, height: 480)
-    # link = link_to(img,
-    #                url,
-    #                target: '_blank',
-    #                rel: 'noopener',
-    #                title: h(@file7.last_revision.try(:tooltip)),
-    #                'data-downloadurl' => "#{@file7.last_revision.content_type}:#{h(@file7.name)}:#{url}")
-    # assert text.include?(link), text
-    height = '480'
-    text = textilizable("{{dmsftn(#{@file7.id}, height=#{height})}}")
-    img = image_tag(url, alt: @file7.name, title: @file7.title, width: 'auto', height: 480)
-    link = link_to(img,
-                   url,
-                   target: '_blank',
-                   rel: 'noopener',
-                   title: h(@file7.last_revision.try(:tooltip)),
-                   'data-downloadurl': 'image/gif:test.gif:http://www.example.com/dmsf/files/7/test.gif')
-    assert text.include?(link), text
-    width = '640'
-    text = textilizable("{{dmsftn(#{@file7.id}, width=#{width})}}")
-    img = image_tag(url, alt: @file7.name, title: @file7.title, width: 640, height: 'auto')
+    assert_equal "<p>#{link.gsub(/redirect\/.*\/#{@file7.name}/, '...')}</p>",
+                 text.gsub(/redirect\/.*\/#{@file7.name}/, '...')
+
+    # Height
+    text = textilizable("{{dmsftn(#{@file7.id}, height=480)}}")
+    img = image_tag(@file7.last_revision&.file&.variant(resize_to_limit: [size, 480]),
+                    alt: @file7.name,
+                    style: "max-width: #{size}px; max-height: 480px;",
+                    loading: 'lazy')
     link = link_to(img,
                    url,
                    target: '_blank',
                    rel: 'noopener',
                    title: h(@file7.last_revision.try(:tooltip)),
                    'data-downloadurl' => "#{@file7.last_revision.content_type}:#{h(@file7.name)}:#{url}")
-    assert text.include?(link), text
+    assert_equal "<p>#{link.gsub(/redirect\/.*\/#{@file7.name}/, '...')}</p>",
+                 text.gsub(/redirect\/.*\/#{@file7.name}/, '...')
+
+    # Width
+    text = textilizable("{{dmsftn(#{@file7.id}, width=640)}}")
+    img = image_tag(@file7.last_revision&.file&.variant(resize_to_limit: [640, size]),
+                    alt: @file7.name,
+                    style: "max-width: 640px; max-height: #{size}px;",
+                    loading: 'lazy')
+    link = link_to(img,
+                   url,
+                   target: '_blank',
+                   rel: 'noopener',
+                   title: h(@file7.last_revision.try(:tooltip)),
+                   'data-downloadurl' => "#{@file7.last_revision.content_type}:#{h(@file7.name)}:#{url}")
+    assert_equal "<p>#{link.gsub(/redirect\/.*\/#{@file7.name}/, '...')}</p>",
+                 text.gsub(/redirect\/.*\/#{@file7.name}/, '...')
   end
 
   def test_macro_dmsftn_no_permissions