diff --git a/exp/color_sampler.py b/exp/color_sampler.py
--- a/exp/color_sampler.py
+++ b/exp/color_sampler.py
@@ -2,18 +2,23 @@ import sys
 sys.path.append("../src")
 
 import os
+import json
+import gzip
+from collections.abc import MutableMapping
 import tkinter as tk
-from tkinter import LEFT,X,N,S,E,W
+from tkinter import LEFT,N,S,E,W
 from colorsys import rgb_to_hsv
 
 from PIL import Image,ImageTk
 
+from analyzer.epoint import EPoint
 from analyzer.corners import Corners
 
 
 class Sampler:
 	def __init__(self):
 		self.dirname="../images"
+		self.annotations=DataFile("annotations.json.gz")
 		self.filenames=[f for f in os.listdir(self.dirname) if f.endswith(".jpg")]
 		self.k=0
 
@@ -24,6 +29,7 @@ class Sampler:
 		self.hsv=(0,0,0)
 		self.pos=(0,0)
 		self.corners=Corners()
+		self._dirty=False
 
 		self._createGUI()
 
@@ -50,7 +56,11 @@ class Sampler:
 		self.canvas.create_image(0,0,image=self.photo,anchor="nw")
 		self.canvas.configure(width=w,height=h)
 
+		self.corners=Corners(self.annotations.get(self.filenames[self.k]) or [])
+		self._markCorners()
+
 	def switchImage(self,step):
+		self.save()
 		n=len(self.filenames)
 		self.k=(self.k+step+n)%n
 		self.showImage()
@@ -61,8 +71,15 @@ class Sampler:
 
 	def addCorner(self,e):
 		self.corners.add(e.x,e.y)
+		self.annotations[self.filenames[self.k]]=list(self.corners)
+		self._dirty=True
 		self._markCorners()
 
+	def save(self):
+		if self._dirty:
+			self.annotations.save()
+			self.dirty=False
+
 	def _createGUI(self):
 		root=tk.Tk()
 		frame=tk.Frame(root)
@@ -111,4 +128,33 @@ class Sampler:
 			self.canvas.create_line(d.x,d.y,a.x,a.y,fill="#00ff00",tags="mark")
 
 
+class DataFile(MutableMapping):
+	def __init__(self,filename):
+		self.filename=filename
+		try:
+			with gzip.open(filename,mode="rt",encoding="utf8") as f:
+				self._data=json.load(f,object_hook=self.deserialize)
+		except OSError:
+			self._data=dict()
+
+	def save(self):
+		with gzip.open(self.filename,mode="wt",encoding="utf8") as f:
+			json.dump(self._data,f,default=self.serialize,indent="\t")
+
+	def serialize(self,obj):
+		if isinstance(obj,EPoint):
+			return {"type": "EPoint", "val": [obj.x,obj.y]}
+		raise TypeError(obj)
+
+	def deserialize(self,obj):
+		if obj.get("type")!="EPoint": return obj
+		return EPoint(*obj["val"])
+
+	def __getitem__(self, key): return self._data[key]
+	def __setitem__(self, key, val): self._data[key]=val
+	def __delitem__(self, key): del self._data[key]
+	def __iter__(self): return iter(self._data)
+	def __len__(self): return len(self._data)
+
+
 s=Sampler()
diff --git a/src/analyzer/corners.py b/src/analyzer/corners.py
--- a/src/analyzer/corners.py
+++ b/src/analyzer/corners.py
@@ -6,8 +6,8 @@ log=logging.getLogger(__name__)
 
 
 class Corners:
-	def __init__(self):
-		self._corners=[]
+	def __init__(self,cornerList=[]):
+		self._corners=cornerList[:]
 
 	## Adds a new corner if there are less than four, replaces the closest otherwise.
 	def add(self,x,y):