diff --git a/.github/workflows/build-release.yml b/.github/workflows/build-release.yml
index 35ae742..3409085 100644
--- a/.github/workflows/build-release.yml
+++ b/.github/workflows/build-release.yml
@@ -90,11 +90,13 @@ jobs:
         run: |
           pip install setuptools wheel && `
           cd .\pyinstaller\bootloader && `
+          (Get-Content .\wscript) -Replace "'run'", "'graxpert'" | Set-Content .\wscript && `
           (Get-Content .\src\main.c) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\main.c && `
           (Get-Content .\src\pyi_main.h) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\pyi_main.h && `
           (Get-Content .\src\pyi_main.c) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\pyi_main.c && `
           python ./waf all && `
           cd .. && `
+          (Get-Content .\setup.py) -Replace 'run.exe', 'graxpert.exe' | Set-Content .\setup.py && `
           python setup.py install && `
           cd .. && `
           pip install -r requirements.txt
@@ -132,11 +134,13 @@ jobs:
         run: |
           pip install setuptools wheel && `
           cd .\pyinstaller\bootloader && `
+          (Get-Content .\wscript) -Replace "'run'", "'graxpert'" | Set-Content .\wscript && `
           (Get-Content .\src\main.c) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\main.c && `
           (Get-Content .\src\pyi_main.h) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\pyi_main.h && `
           (Get-Content .\src\pyi_main.c) -Replace 'pyi_main\(', 'my_pyi_main(' | Set-Content .\src\pyi_main.c && `
           python ./waf all && `
           cd .. && `
+          (Get-Content .\setup.py) -Replace 'run.exe', 'graxpert.exe' | Set-Content .\setup.py && `
           python setup.py install && `
           cd .. && `
           pip install -r requirements.txt
@@ -229,4 +233,4 @@ jobs:
             GraXpert-win64.exe
             GraXpert-linux.zip
             GraXpert-win64.zip
-            GraXpert-macos-x86_64.dmg
+            GraXpert-macos-x86_64.dmg
\ No newline at end of file
diff --git a/forest-dark.tcl b/forest-dark.tcl
index 41222f8..3bb8db4 100644
--- a/forest-dark.tcl
+++ b/forest-dark.tcl
@@ -248,7 +248,7 @@ namespace eval ttk::theme::forest-dark {
             ] -border 4 -sticky nsew
 
         # Menubutton
-        ttk::style configure TMenubutton -padding {8 4 4 4}
+        ttk::style configure TMenubutton -padding {8 4 4 4} -anchor center
 
         ttk::style element create Menubutton.button image \
             [list $I(rect-basic) \
diff --git a/locales/de_DE/LC_MESSAGES/base.mo b/locales/de_DE/LC_MESSAGES/base.mo
index 251514d..ff19da2 100644
Binary files a/locales/de_DE/LC_MESSAGES/base.mo and b/locales/de_DE/LC_MESSAGES/base.mo differ
diff --git a/locales/de_DE/LC_MESSAGES/base.po b/locales/de_DE/LC_MESSAGES/base.po
index 0807701..d798f7c 100644
--- a/locales/de_DE/LC_MESSAGES/base.po
+++ b/locales/de_DE/LC_MESSAGES/base.po
@@ -14,6 +14,17 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Generated-By: pygettext.py 1.5\n"
 
+msgid "Crop"
+msgstr "Zuschneiden"
+
+msgid "Crop mode on/off"
+msgstr "Zuschnittsmodus an/aus"
+
+msgid "Apply crop"
+msgstr "Zuschnitt anwenden"
+
+msgid "Background Extraction"
+msgstr "Hintergrundentfernung"
 
 #: src/gui.py:147
 msgid " Loading"
@@ -21,7 +32,7 @@ msgstr " Laden"
 
 #: src/gui.py:152
 msgid "Load Image"
-msgstr "Lade Bild"
+msgstr "Bild laden"
 
 #: src/gui.py:160
 msgid " Stretch Options"
@@ -33,7 +44,7 @@ msgstr " Punktauswahl"
 
 #: src/gui.py:176
 msgid "Display points"
-msgstr "Zeige Punkte"
+msgstr "Punkte anzeigen"
 
 #: src/gui.py:185 src/gui.py:191
 msgid "Points per row: {}"
@@ -45,7 +56,7 @@ msgstr "Gittertoleranz: {}"
 
 #: src/gui.py:231
 msgid "Create Grid"
-msgstr "Erstelle Gitter"
+msgstr "Gitter erstellen"
 
 #: src/gui.py:237
 msgid "Reset Sample Points"
@@ -61,7 +72,7 @@ msgstr "Interpolationsmethode"
 
 #: src/gui.py:287
 msgid "Calculate Background"
-msgstr "Berechne Hintergrund"
+msgstr "Hintergrund berechnen"
 
 #: src/gui.py:294
 msgid " Saving"
@@ -69,11 +80,11 @@ msgstr " Speichern"
 
 #: src/gui.py:308
 msgid "Save Background"
-msgstr "Speichere Hintergrund"
+msgstr "Hintergrund speichern"
 
 #: src/gui.py:315
 msgid "Save Processed"
-msgstr "Speichere Bild"
+msgstr "Bild speichern"
 
 #: src/gui.py:345
 msgid "An error occurred while loading your picture."
@@ -204,6 +215,12 @@ msgstr "Samplefarbe: {}"
 msgid "Spline order"
 msgstr "Grad der Splines"
 
+msgid "Language"
+msgstr "Sprache"
+
+msgid "Correction"
+msgstr "Korrektur"
+
 #: src/loadingframe.py:18
 msgid "Calculating..."
 msgstr "Berechne..."
diff --git a/src/astroimage.py b/src/astroimage.py
index ca2965c..57c8b42 100644
--- a/src/astroimage.py
+++ b/src/astroimage.py
@@ -65,8 +65,8 @@ def update_display(self):
         img_display = self.stretch()
         img_display = img_display*255
         
-        if self.roworder == "TOP-DOWN":
-            img_display = np.flip(img_display, axis=0)
+        #if self.roworder == "TOP-DOWN":
+        #    img_display = np.flip(img_display, axis=0)
         
         if(img_display.shape[2] == 1):
             self.img_display = Image.fromarray(img_display[:,:,0].astype(np.uint8))
@@ -77,8 +77,8 @@ def update_display(self):
     def update_display_from_array(self, img_display):
         img_display = img_display*255
         
-        if self.roworder == "TOP-DOWN":
-            img_display = np.flip(img_display, axis=0)
+        #if self.roworder == "TOP-DOWN":
+        #    img_display = np.flip(img_display, axis=0)
         
         if(img_display.shape[2] == 1):
             self.img_display = Image.fromarray(img_display[:,:,0].astype(np.uint8))
@@ -118,6 +118,13 @@ def get_stretch(self):
         elif(self.stretch_option.get() == "30% Bg, 2 sigma"):
             return (0.3, 2)
     
+    def crop(self, startx, endx, starty, endy):
+        self.img_array = self.img_array[starty:endy,startx:endx,:]
+        self.img_display = self.img_display.crop((startx, starty, endx, endy))
+        self.width = self.img_array.shape[1]
+        self.height = self.img_array.shape[0]        
+        return
+    
     def update_fits_header(self, original_header, background_mean):
         if(original_header is None):
             self.fits_header = fits.Header()
diff --git a/src/background_extraction.py b/src/background_extraction.py
index 03200ad..ddd2e68 100644
--- a/src/background_extraction.py
+++ b/src/background_extraction.py
@@ -23,7 +23,8 @@
 from radialbasisinterpolation import RadialBasisInterpolation
 
 
-def extract_background(in_imarray, background_points, interpolation_type, smoothing, downscale_factor, sample_size, RBF_kernel, spline_order):
+def extract_background(in_imarray, background_points, interpolation_type, smoothing, 
+                       downscale_factor, sample_size, RBF_kernel, spline_order, corr_type):
 
     shm_imarray = shared_memory.SharedMemory(create=True, size=in_imarray.nbytes)
     shm_background = shared_memory.SharedMemory(create=True, size=in_imarray.nbytes)
@@ -40,10 +41,15 @@ def extract_background(in_imarray, background_points, interpolation_type, smooth
     for c in range(num_colors):
         futures.insert(c, executor.submit(interpol, shm_imarray.name, shm_background.name, c, x_sub, y_sub, in_imarray.shape, interpolation_type, smoothing, downscale_factor, sample_size, RBF_kernel, spline_order, imarray.dtype))
     wait(futures)
-        
-    #Subtract background from image
-    mean = np.mean(background)
-    imarray[:,:,:] = imarray[:,:,:] - background[:,:,:] + mean
+    
+    #Correction
+    if(corr_type == "Subtraction"):
+        mean = np.mean(background)
+        imarray[:,:,:] = imarray[:,:,:] - background[:,:,:] + mean
+    elif(corr_type == "Division"):
+        for c in range(num_colors):
+            mean = np.mean(imarray[:,:,c])
+            imarray[:,:,c] = imarray[:,:,c] / background[:,:,c] * mean
 
     #clip image
     imarray[:,:,:] = imarray.clip(min=0.0,max=1.0)
diff --git a/src/collapsible_frame.py b/src/collapsible_frame.py
new file mode 100644
index 0000000..fa9e820
--- /dev/null
+++ b/src/collapsible_frame.py
@@ -0,0 +1,36 @@
+import tkinter as tk
+from tkinter import ttk 
+
+class CollapsibleFrame(tk.Frame):
+
+    def __init__(self, parent, text="", *args, **options):
+        tk.Frame.__init__(self, parent, *args, **options)
+
+        self.show = tk.IntVar()
+        self.show.set(0)
+
+        self.title_frame = ttk.Frame(self)
+        self.title_frame.pack(fill="x", expand=1)
+
+        ttk.Label(self.title_frame, text=text, font="Verdana 10 bold").pack(side="left", fill="x", expand=1)
+
+        self.toggle_button = ttk.Checkbutton(self.title_frame, width=2, text='+', command=self.toggle,
+                                            variable=self.show, style='Toolbutton')
+        self.toggle_button.pack(side="left")
+
+        self.sub_frame = tk.Frame(self, relief="sunken", borderwidth=0)
+
+    def toggle(self):
+        if bool(self.show.get()):
+            self.sub_frame.pack(fill="x", expand=1)
+            self.toggle_button.configure(text='-')
+        else:
+            self.sub_frame.forget()
+            self.toggle_button.configure(text='+')
+        
+        self.update()
+        self.master.update()
+        width = self.master.winfo_width()
+        self.master.master.configure(width=width)
+        self.master.master.configure(scrollregion=self.master.master.bbox("all"))
+        self.master.master.yview_moveto("0.0")
\ No newline at end of file
diff --git a/src/gui.py b/src/gui.py
index df06ebd..875a1fe 100644
--- a/src/gui.py
+++ b/src/gui.py
@@ -23,6 +23,7 @@
 from preferences import app_state_2_prefs, load_preferences, prefs_2_app_state, save_preferences
 from stretch import stretch_all
 import tooltip
+from collapsible_frame import CollapsibleFrame
 from loadingframe import LoadingFrame
 from help_panel import Help_Panel
 from astroimage import AstroImage
@@ -81,6 +82,8 @@ def __init__(self, master=None):
         self.cmd.execute()
 
         self.create_widget()
+        self.bgextr_menu.show.set(1)
+        self.bgextr_menu.toggle()
 
         self.reset_transform()
         
@@ -122,6 +125,8 @@ def create_widget(self):
         self.clicked_inside_pt_idx = 0
         self.clicked_inside_pt_coord = None
         
+        self.crop_mode = False
+        
         self.master.bind("<Button-1>", self.mouse_down_left)  
         self.master.bind("<ButtonRelease-1>", self.mouse_release_left)         # Left Mouse Button
         self.master.bind("<Button-2>", self.mouse_down_right)                  # Middle Mouse Button (Right Mouse Button on macs)
@@ -140,6 +145,8 @@ def create_widget(self):
         
         
         #Side menu
+        heading_font = "Verdana 10 bold"
+        
         self.side_canvas = tk.Canvas(self.master, borderwidth=0,  bd=0, highlightthickness=0, name="left_panel")
         self.side_canvas.pack(side=tk.TOP, fill=tk.Y, expand=True)
         
@@ -148,22 +155,43 @@ def create_widget(self):
         
  
         scal = get_scaling_factor(self.master)*0.75
-        self.side_menu = tk.Frame(self.side_canvas, borderwidth=0)
-
+        self.side_menu = tk.Frame(self.side_canvas)
+        
+        #Crop menu
+        self.crop_menu = CollapsibleFrame(self.side_menu, text=_("Crop") + " ")
+        self.crop_menu.grid(column=0, row=0, pady=(20*scal,5*scal), padx=15*scal, sticky="news")
+        self.crop_menu.sub_frame.grid_columnconfigure(0, weight=1)
+        
+        for i in range(2):
+            self.crop_menu.sub_frame.grid_rowconfigure(i, weight=1)
+            
+        self.cropmode_button = ttk.Button(self.crop_menu.sub_frame, 
+                          text=_("Crop mode on/off"),
+                          command=self.toggle_crop_mode,
+        )
+        self.cropmode_button.grid(column=0, row=0, pady=(20*scal,5*scal), padx=15*scal, sticky="news")
+        
+        self.cropapply_button = ttk.Button(self.crop_menu.sub_frame, 
+                          text=_("Apply crop"),
+                          command=self.crop_apply,
+        )
+        self.cropapply_button.grid(column=0, row=1, pady=(5*scal,20*scal), padx=15*scal, sticky="news")
         
-        self.side_menu.grid_columnconfigure(0)
+        #Background extraction menu
+        self.bgextr_menu = CollapsibleFrame(self.side_menu, text=_("Background Extraction") + " ")
+        self.bgextr_menu.grid(column=0, row=1, pady=(5*scal,20*scal), padx=15*scal, sticky="news")
+        self.bgextr_menu.sub_frame.grid_columnconfigure(0, weight=1)
         
         for i in range(21):
-            self.side_menu.grid_rowconfigure(i, weight=1)
+            self.bgextr_menu.sub_frame.grid_rowconfigure(i, weight=1)
         
-        heading_font = "Verdana 10 bold"
         #---Open Image---
         num_pic = ImageTk.PhotoImage(file=resource_path("img/gfx_number_1-scaled.png"))
-        text = tk.Label(self.side_menu, text=_(" Loading"), image=num_pic, font=heading_font, compound="left")
+        text = tk.Label(self.bgextr_menu.sub_frame, text=_(" Loading"), image=num_pic, font=heading_font, compound="left")
         text.image = num_pic
         text.grid(column=0, row=0, pady=(20*scal,5*scal), padx=0, sticky="w")
         
-        self.load_image_button = ttk.Button(self.side_menu, 
+        self.load_image_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Load Image"),
                          command=self.menu_open_clicked,
         )
@@ -172,7 +200,7 @@ def create_widget(self):
         
         #--Stretch Options--
         num_pic = ImageTk.PhotoImage(file=resource_path("img/gfx_number_2-scaled.png"))
-        text = tk.Label(self.side_menu, text=_(" Stretch Options"), image=num_pic, font=heading_font, compound="left")
+        text = tk.Label(self.bgextr_menu.sub_frame, text=_(" Stretch Options"), image=num_pic, font=heading_font, compound="left")
         text.image = num_pic
         text.grid(column=0, row=2, pady=5*scal, padx=0, sticky="w")
         
@@ -181,20 +209,20 @@ def create_widget(self):
         self.stretch_option_current.set(self.stretch_options[0])
         if "stretch_option" in self.prefs:
             self.stretch_option_current.set(self.prefs["stretch_option"])
-        self.stretch_menu = ttk.OptionMenu(self.side_menu, self.stretch_option_current, self.stretch_option_current.get(), *self.stretch_options, command=self.change_stretch)
+        self.stretch_menu = ttk.OptionMenu(self.bgextr_menu.sub_frame, self.stretch_option_current, self.stretch_option_current.get(), *self.stretch_options, command=self.change_stretch)
         self.stretch_menu.grid(column=0, row=3, pady=(5*scal,30*scal), padx=15*scal, sticky="news")
         tt_stretch= tooltip.Tooltip(self.stretch_menu, text=tooltip.stretch_text)
         
       
         #---Sample Selection---
         num_pic = ImageTk.PhotoImage(file=resource_path("img/gfx_number_3-scaled.png"))
-        text = tk.Label(self.side_menu, text=_(" Sample Selection"), image=num_pic, font=heading_font, compound="left")
+        text = tk.Label(self.bgextr_menu.sub_frame, text=_(" Sample Selection"), image=num_pic, font=heading_font, compound="left")
         text.image = num_pic
         text.grid(column=0, row=4, pady=5*scal, padx=0, sticky="w")
         
         self.display_pts = tk.BooleanVar()
         self.display_pts.set(True)
-        self.display_pts_switch = ttk.Checkbutton(self.side_menu, text="  "+_("Display points"), compound=tk.LEFT, var=self.display_pts, command=self.redraw_points)
+        self.display_pts_switch = ttk.Checkbutton(self.bgextr_menu.sub_frame, text="  "+_("Display points"), compound=tk.LEFT, var=self.display_pts, command=self.redraw_points)
         self.display_pts_switch.grid(column=0, row=5, pady=(5*scal,5*scal), padx=15*scal, sticky="ews")
         
         self.bg_pts = tk.IntVar()
@@ -202,7 +230,7 @@ def create_widget(self):
         if "bg_pts_option" in self.prefs:
             self.bg_pts.set(self.prefs["bg_pts_option"])
         
-        self.bg_selection_text = tk.Message(self.side_menu, text=_("Points per row: {}").format(self.bg_pts.get()))
+        self.bg_selection_text = tk.Message(self.bgextr_menu.sub_frame, text=_("Points per row: {}").format(self.bg_pts.get()))
         self.bg_selection_text.config(width=500 * scal)
         self.bg_selection_text.grid(column=0, row=6, pady=(5*scal,5*scal), padx=15*scal, sticky="ews")
         
@@ -211,7 +239,7 @@ def on_bg_pts_slider(bgs_points):
             self.bg_selection_text.configure(text=_("Points per row: {}").format(self.bg_pts.get()))
 
         self.bg_pts_slider = ttk.Scale(
-            self.side_menu,
+            self.bgextr_menu.sub_frame,
             orient=tk.HORIZONTAL,
             from_=4,
             to=25,
@@ -228,7 +256,7 @@ def on_bg_pts_slider(bgs_points):
         if "bg_tol_option" in self.prefs:
             self.bg_tol.set(self.prefs["bg_tol_option"])
         
-        self.bg_selection_tol = tk.Message(self.side_menu, text=_("Grid Tolerance: {}").format(self.bg_tol.get()))
+        self.bg_selection_tol = tk.Message(self.bgextr_menu.sub_frame, text=_("Grid Tolerance: {}").format(self.bg_tol.get()))
         self.bg_selection_tol.config(width=500)
         self.bg_selection_tol.grid(column=0, row=8, pady=(5*scal,5*scal), padx=15*scal, sticky="ews")
         
@@ -237,7 +265,7 @@ def on_bg_tol_slider(bg_tol):
             self.bg_selection_tol.configure(text=_("Grid Tolerance: {}").format(self.bg_tol.get()))
         
         self.bg_tol_slider = ttk.Scale(
-            self.side_menu,
+            self.bgextr_menu.sub_frame,
             orient=tk.HORIZONTAL,
             from_=-2,
             to=10,
@@ -248,13 +276,13 @@ def on_bg_tol_slider(bg_tol):
         self.bg_tol_slider.grid(column=0, row=9, pady=(0,10*scal), padx=15*scal, sticky="ew")
         tt_tol_points= tooltip.Tooltip(self.bg_tol_slider, text=tooltip.bg_tol_text)
         
-        self.bg_selection_button = ttk.Button(self.side_menu, 
+        self.bg_selection_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Create Grid"),
                          command=self.select_background)
         self.bg_selection_button.grid(column=0, row=10, pady=5*scal, padx=15*scal, sticky="news")
         tt_bg_select = tooltip.Tooltip(self.bg_selection_button, text= tooltip.bg_select_text)
         
-        self.reset_button = ttk.Button(self.side_menu, 
+        self.reset_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Reset Sample Points"),
                          command=self.reset_backgroundpts)
         self.reset_button.grid(column=0, row=11, pady=(5*scal,30*scal), padx=15*scal, sticky="news")
@@ -262,11 +290,11 @@ def on_bg_tol_slider(bg_tol):
         
         #---Calculation---
         num_pic = ImageTk.PhotoImage(file=resource_path("img/gfx_number_4-scaled.png"))
-        text = tk.Label(self.side_menu, text=_(" Calculation"), image=num_pic, font=heading_font, compound="left")
+        text = tk.Label(self.bgextr_menu.sub_frame, text=_(" Calculation"), image=num_pic, font=heading_font, compound="left")
         text.image = num_pic
         text.grid(column=0, row=12, pady=5*scal, padx=0, sticky="w")
         
-        self.intp_type_text = tk.Message(self.side_menu, text=_("Interpolation Method:"))
+        self.intp_type_text = tk.Message(self.bgextr_menu.sub_frame, text=_("Interpolation Method:"))
         self.intp_type_text.config(width=500)
         self.intp_type_text.grid(column=0, row=13, pady=(5*scal,5*scal), padx=15*scal, sticky="ews")
         
@@ -275,7 +303,7 @@ def on_bg_tol_slider(bg_tol):
         self.interpol_type.set(self.interpol_options[0])
         if "interpol_type_option" in self.prefs:
             self.interpol_type.set(self.prefs["interpol_type_option"])
-        self.interpol_menu = ttk.OptionMenu(self.side_menu, self.interpol_type, self.interpol_type.get(), *self.interpol_options)
+        self.interpol_menu = ttk.OptionMenu(self.bgextr_menu.sub_frame, self.interpol_type, self.interpol_type.get(), *self.interpol_options)
         self.interpol_menu.grid(column=0, row=14, pady=(0,5*scal), padx=15*scal, sticky="news")
         tt_interpol_type= tooltip.Tooltip(self.interpol_menu, text=tooltip.interpol_type_text)
         
@@ -284,7 +312,7 @@ def on_bg_tol_slider(bg_tol):
         if "smoothing_option" in self.prefs:
             self.smoothing.set(self.prefs["smoothing_option"])
         
-        self.smooth_text = tk.Message(self.side_menu, text="Smoothing: {}".format(self.smoothing.get()))
+        self.smooth_text = tk.Message(self.bgextr_menu.sub_frame, text="Smoothing: {}".format(self.smoothing.get()))
         self.smooth_text.config(width=500)
         self.smooth_text.grid(column=0, row=15, pady=(5*scal,5*scal), padx=15*scal, sticky="ews")
         
@@ -293,7 +321,7 @@ def on_smoothing_slider(smoothing):
             self.smooth_text.configure(text="Smoothing: {}".format(self.smoothing.get()))
         
         self.smoothing_slider = ttk.Scale(
-            self.side_menu,
+            self.bgextr_menu.sub_frame,
             orient=tk.HORIZONTAL,
             from_=0,
             to=1,
@@ -304,7 +332,7 @@ def on_smoothing_slider(smoothing):
         self.smoothing_slider.grid(column=0, row=16, pady=(0,10*scal), padx=15*scal, sticky="ew")
         tt_smoothing= tooltip.Tooltip(self.smoothing_slider, text=tooltip.smoothing_text)
         
-        self.calculate_button = ttk.Button(self.side_menu, 
+        self.calculate_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Calculate Background"),
                          command=self.calculate)
         self.calculate_button.grid(column=0, row=17, pady=(5*scal,30*scal), padx=15*scal, sticky="news")
@@ -312,7 +340,7 @@ def on_smoothing_slider(smoothing):
         
         #---Saving---  
         num_pic = ImageTk.PhotoImage(file=resource_path("img/gfx_number_5-scaled.png"))
-        self.saveas_text = tk.Label(self.side_menu, text=_(" Saving"), image=num_pic, font=heading_font, compound="left")
+        self.saveas_text = tk.Label(self.bgextr_menu.sub_frame, text=_(" Saving"), image=num_pic, font=heading_font, compound="left")
         self.saveas_text.image = num_pic
         self.saveas_text.grid(column=0, row=18, pady=5*scal, padx=0, sticky="w")
         
@@ -321,24 +349,24 @@ def on_smoothing_slider(smoothing):
         self.saveas_type.set(self.saveas_options[0])
         if "saveas_option" in self.prefs:
             self.saveas_type.set(self.prefs["saveas_option"])
-        self.saveas_menu = ttk.OptionMenu(self.side_menu, self.saveas_type, self.saveas_type.get(), *self.saveas_options)
+        self.saveas_menu = ttk.OptionMenu(self.bgextr_menu.sub_frame, self.saveas_type, self.saveas_type.get(), *self.saveas_options)
         self.saveas_menu.grid(column=0, row=19, pady=(5*scal,20*scal), padx=15*scal, sticky="news")
         tt_interpol_type= tooltip.Tooltip(self.saveas_menu, text=tooltip.saveas_text)
         
-        self.save_background_button = ttk.Button(self.side_menu, 
+        self.save_background_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Save Background"),
                          command=self.save_background_image)
         self.save_background_button.grid(column=0, row=20, pady=5*scal, padx=15*scal, sticky="news")
         tt_save_bg = tooltip.Tooltip(self.save_background_button, text=tooltip.save_bg_text)
               
         
-        self.save_button = ttk.Button(self.side_menu, 
+        self.save_button = ttk.Button(self.bgextr_menu.sub_frame, 
                          text=_("Save Processed"),
                          command=self.save_image)
         self.save_button.grid(column=0, row=21, pady=(5*scal,10*scal), padx=15*scal, sticky="news")
         tt_save_pic= tooltip.Tooltip(self.save_button, text=tooltip.save_pic_text)
         
-        
+
         self.side_canvas.create_window((0,0), window=self.side_menu)
         self.side_canvas.configure(yscrollcommand=self.scrollbar.set)
         self.side_canvas.bind('<Configure>', lambda e: self.side_canvas.configure(scrollregion=self.side_canvas.bbox("all")))
@@ -346,6 +374,7 @@ def on_smoothing_slider(smoothing):
         width = self.side_menu.winfo_width()
         self.side_canvas.configure(width=width)
         self.side_canvas.yview_moveto("0.0")
+
     
     def menu_open_clicked(self, event=None):
 
@@ -402,6 +431,42 @@ def menu_open_clicked(self, event=None):
         self.loading_frame.end()
         return
     
+    def toggle_crop_mode(self):
+        
+        if self.images["Original"] is None:
+            messagebox.showerror("Error", _("Please load your picture first."))
+            return
+        
+        self.startx = 0
+        self.starty = 0
+        self.endx = self.images["Original"].width
+        self.endy = self.images["Original"].height
+
+        if(self.crop_mode):
+            self.crop_mode = False
+        else:
+            self.crop_mode = True
+        
+        self.redraw_points()
+        
+    def crop_apply(self):
+        
+        if (not self.crop_mode):
+            return
+        
+        for astroimg in self.images.values():
+            if(astroimg is not None):
+                astroimg.crop(self.startx, self.endx, self.starty, self.endy)
+
+        self.reset_backgroundpts()
+        self.crop_mode = False
+        self.zoom_fit(self.images[self.display_type.get()].width, self.images[self.display_type.get()].height)
+        self.redraw_image()
+        self.redraw_points()
+        return
+        
+        
+        
     def select_background(self,event=None):
         
         if self.images["Original"] is None:
@@ -540,7 +605,8 @@ def calculate(self):
             imarray,np.array(background_points),
             self.interpol_type.get(),self.smoothing.get(),
             downscale_factor, self.sample_size.get(),
-            self.RBF_kernel.get(),self.spline_order.get()
+            self.RBF_kernel.get(),self.spline_order.get(),
+            self.corr_type.get()
             ))
 
         self.images["Processed"] = AstroImage(self.stretch_option_current)
@@ -603,6 +669,13 @@ def mouse_down_left(self,event):
                 self.clicked_inside_pt = True
                 self.clicked_inside_pt_idx = min_idx
                 self.clicked_inside_pt_coord = self.cmd.app_state["background_points"][min_idx]
+        
+        if(self.crop_mode):
+            #Check if inside circles to move crop corners
+            corner1 = self.to_canvas_point(self.startx, self.starty)
+            corner2 = self.to_canvas_point(self.endx, self.endy)
+            if((event.x - corner1[0])**2 + (event.y - corner1[1])**2 < 15**2 or (event.x - corner2[0])**2 + (event.y - corner2[1])**2 < 15**2):
+                self.clicked_inside_pt = True
                 
         self.__old_event = event
 
@@ -613,7 +686,7 @@ def mouse_release_left(self,event):
             return
         
 
-        if self.clicked_inside_pt:            
+        if self.clicked_inside_pt and not self.crop_mode:            
             new_point = self.to_image_point(event.x,event.y)
             self.cmd.app_state["background_points"][self.clicked_inside_pt_idx] = self.clicked_inside_pt_coord
             self.cmd = Command(MOVE_POINT_HANDLER, prev=self.cmd, new_point=new_point, idx=self.clicked_inside_pt_idx)
@@ -642,13 +715,29 @@ def mouse_move_left(self, event):
         if(self.left_drag_timer == -1):
             self.left_drag_timer = event.time
         
-        if self.clicked_inside_pt and self.display_pts.get():         
+        if(self.clicked_inside_pt and self.display_pts.get() and not self.crop_mode):         
             new_point = self.to_image_point(event.x, event.y)
             if len(new_point) != 0:
                 self.cmd.app_state["background_points"][self.clicked_inside_pt_idx] = new_point
                 
             self.redraw_points()
             
+        elif(self.clicked_inside_pt and self.crop_mode):
+            new_point = self.to_image_point_pinned(event.x, event.y)
+            corner1_canvas = self.to_canvas_point(self.startx, self.starty)
+            corner2_canvas = self.to_canvas_point(self.endx, self.endy)
+            
+            dist1 = (event.x - corner1_canvas[0])**2 + (event.y - corner1_canvas[1])**2
+            dist2 = (event.x - corner2_canvas[0])**2 + (event.y - corner2_canvas[1])**2
+            if(dist1 < dist2):
+                self.startx = int(new_point[0])
+                self.starty = int(new_point[1])
+            else:
+                self.endx = int(new_point[0])
+                self.endy = int(new_point[1])
+                
+            self.redraw_points()
+                
         else:
             if(event.time - self.left_drag_timer >= 100):            
                 self.translate(event.x - self.__old_event.x, event.y - self.__old_event.y)
@@ -860,6 +949,28 @@ def to_image_point(self, x, y):
 
         return image_point
 
+    def to_image_point_pinned(self, x, y):
+        
+        if self.images[self.display_type.get()] is None:
+            return []
+
+        mat_inv = np.linalg.inv(self.mat_affine)
+        image_point = np.dot(mat_inv, (x, y, 1.))
+        
+        width = self.images[self.display_type.get()].width
+        height = self.images[self.display_type.get()].height
+        
+        if image_point[0] < 0:
+            image_point[0] = 0
+        if image_point[1] < 0:
+            image_point[1] = 0
+        if image_point[0] > width:
+            image_point[0] = width
+        if image_point[1] > height:
+            image_point[1] = height
+
+        return image_point
+    
     def to_canvas_point(self, x, y):
         
         return np.dot(self.mat_affine,(x,y,1.))
@@ -912,16 +1023,23 @@ def redraw_points(self):
         color = (int(color[0]*255), int(color[1]*255), int(color[2]*255))
         color = '#%02x%02x%02x' % color
         
-        self.canvas.delete("rectangle")      
+        self.canvas.delete("sample")
+        self.canvas.delete("crop")  
         rectsize = self.sample_size.get()
         background_points = self.cmd.app_state["background_points"]
         
-        if self.display_pts.get():
+        if self.display_pts.get() and not self.crop_mode:
             for point in background_points:        
                 corner1 = self.to_canvas_point(point[0]-rectsize,point[1]-rectsize)
                 corner2 = self.to_canvas_point(point[0]+rectsize,point[1]+rectsize)
-                self.canvas.create_rectangle(corner1[0],corner1[1], corner2[0],corner2[1],outline=color, width=2, tags="rectangle")
-            
+                self.canvas.create_rectangle(corner1[0],corner1[1], corner2[0],corner2[1],outline=color, width=2, tags="sample")
+        
+        if self.crop_mode:
+            corner1 = self.to_canvas_point(self.startx, self.starty)
+            corner2 = self.to_canvas_point(self.endx, self.endy)
+            self.canvas.create_rectangle(corner1[0],corner1[1], corner2[0],corner2[1], outline=color, width=2, tags="crop")
+            self.canvas.create_oval(corner1[0]-15,corner1[1]-15, corner1[0]+15,corner1[1]+15, outline=color, width=2, tags="crop")
+            self.canvas.create_oval(corner2[0]-15,corner2[1]-15, corner2[0]+15,corner2[1]+15, outline=color, width=2, tags="crop")
         return
 
     def redraw_image(self):
@@ -966,6 +1084,7 @@ def on_closing(self):
         self.prefs["RBF_kernel"] = self.RBF_kernel.get()
         self.prefs["spline_order"] = self.spline_order.get()
         self.prefs["lang"] = self.lang.get()
+        self.prefs["corr_type"] = self.corr_type.get()
         prefs_filename = os.path.join(user_config_dir(), ".graxpert", "preferences.json")
         save_preferences(prefs_filename, self.prefs)
         try:
@@ -1010,8 +1129,9 @@ def scale_img(path, scaling, shape):
     
     root.tk.call("source", resource_path("forest-dark.tcl"))   
     style = ttk.Style(root)
-    style.configure("Scale.slider", sliderlength=100, sliderthickness=100)
     style.theme_use("forest-dark")
+    style.configure("TButton", padding=(8*scaling, 12*scaling, 8*scaling, 12*scaling))
+    style.configure("TMenubutton", padding=(8*scaling, 4*scaling, 4*scaling, 4*scaling))
     root.tk.call("wm", "iconphoto", root._w, tk.PhotoImage(file=resource_path("img/Icon.png")))
     root.tk.call('tk', 'scaling', scaling)
     root.option_add("*TkFDialog*foreground", "black")
diff --git a/src/help_panel.py b/src/help_panel.py
index 7bae1e7..f66fe7d 100644
--- a/src/help_panel.py
+++ b/src/help_panel.py
@@ -322,6 +322,20 @@ def lang_change(lang):
         self.lang_menu.grid(column=0, row=12, pady=(5*scaling,5*scaling), padx=(40,30), sticky="ews")
         
         
+        text = tk.Message(self.advanced_panel_window, text=_("Correction"), width=240 * scaling, font=heading_font2, anchor="center")
+        text.grid(column=0, row=13, padx=(10*scaling,10*scaling), pady=(20*scaling,10*scaling), sticky="ew")
+        
+        
+        self.app.corr_types = ["Subtraction", "Division"]
+        self.app.corr_type = tk.StringVar()
+        self.app.corr_type.set(self.app.corr_types[0])
+        if "corr_type" in self.app.prefs:
+            self.app.corr_type.set(self.app.prefs["corr_type"])
+
+        self.corr_menu = ttk.OptionMenu(self.advanced_panel_window, self.app.corr_type, self.app.corr_type.get(), *self.app.corr_types)
+        self.corr_menu.grid(column=0, row=14, pady=(5*scaling,5*scaling), padx=(40,30), sticky="ews")
+        
+        
         self.advanced_canvas.create_window((0,0), window=self.advanced_panel_window)
         self.advanced_canvas.configure(yscrollcommand=self.advanced_scrollbar.set)
         self.advanced_canvas.bind('<Configure>', lambda e: self.advanced_canvas.configure(scrollregion=self.advanced_canvas.bbox("all")))
diff --git a/src/preferences.py b/src/preferences.py
index b82709a..6028825 100644
--- a/src/preferences.py
+++ b/src/preferences.py
@@ -24,6 +24,7 @@ class Prefs(TypedDict):
     sample_color: int
     RBF_kernel: AnyStr
     lang: AnyStr
+    corr_type: AnyStr
 
 DEFAULT_PREFS: Prefs = {
     "working_dir": os.getcwd(),
@@ -40,7 +41,8 @@ class Prefs(TypedDict):
     "sample_color": 55,
     "RBF_kernel": "thin_plate",
     "spline_order": 3,
-    "lang": None
+    "lang": None,
+    "corr_type": "Subtraction"
 }
 
 def app_state_2_prefs(prefs: Prefs, app_state: AppState) -> Prefs:
@@ -84,6 +86,8 @@ def merge_json(prefs: Prefs, json) -> Prefs:
         prefs["spline_order"] = json["spline_order"]
     if "lang" in json:
         prefs["lang"] = json["lang"]
+    if "corr_type" in json:
+        prefs["corr_type"] = json["corr_type"]
     return prefs
 
 def load_preferences(prefs_filename) -> Prefs:
diff --git a/src/ui_scaling.py b/src/ui_scaling.py
index 71d2302..9009c47 100644
--- a/src/ui_scaling.py
+++ b/src/ui_scaling.py
@@ -1,4 +1,5 @@
 from screeninfo import get_monitors
+from platform import system
 
 scaling_factor = None
 
@@ -23,9 +24,10 @@ def get_scaling_factor(master):
             except:
                 # ... if that fails try the first one in the list
                 monitor = monitors[0]
-                
-        dpi = monitor.width / (monitor.width_mm / 24.0)
-        scaling_factor = dpi / 72.0
+        
+        dpi = monitor.width / (monitor.width_mm / 25.4)
+        scaling_factor = dpi / 96.0
+        
     except BaseException as e:
         print("WARNING: could not calculate monitor dpi:", e)
         scaling_factor = 1.0