diff --git a/src/core.py b/src/core.py
--- a/src/core.py
+++ b/src/core.py
@@ -2,7 +2,9 @@ import os
 import multiprocessing
 import threading
 import logging
+
 import PIL
+
 from util import MsgQueue
 from gui import gui
 from analyzer import ImageAnalyzer
@@ -10,6 +12,7 @@ from analyzer.framecache import FrameCac
 from go.core import Go, isLegalPosition
 from statebag import StateBag
 import config as cfg
+import util
 
 log=logging.getLogger(__name__)
 
@@ -25,7 +28,7 @@ class Core:
 		self._ownMessages=MsgQueue(self._handleEvent)
 		self._guiMessages=MsgQueue()
 
-		self._imgs=sorted(os.listdir(cfg.misc.imgDir))
+		self._imgs=sorted(filter(lambda s: s.endswith(".jpg"), os.listdir(cfg.misc.imgDir)))
 		self._imgIndex=cfg.misc.defaultImage
 		imgPath=os.path.join(cfg.misc.imgDir,self._imgs[self._imgIndex])
 		self._frame=PIL.Image.open(imgPath)
@@ -45,9 +48,10 @@ class Core:
 
 	def relativeFrame(self,step):
 		self._imgIndex=(self._imgIndex+step)%len(self._imgs)
-		imgPath=os.path.join(cfg.misc.imgDir,self._imgs[self._imgIndex])
+		filename=self._imgs[self._imgIndex]
+		imgPath=os.path.join(cfg.misc.imgDir,filename)
 		self._frame=PIL.Image.open(imgPath)
-		self._guiMessages.send("setCurrentFrame",(self._frame.copy(),gui.PREVIEW))
+		self._guiMessages.send("setCurrentFrame",(self._frame.copy(),gui.PREVIEW,filename))
 		self.preview()
 
 	def sendParams(self):
diff --git a/src/gui/__init__.py b/src/gui/__init__.py
--- a/src/gui/__init__.py
+++ b/src/gui/__init__.py
@@ -1,4 +1,6 @@
-import logging
+import os
+import json
+import logging
 import threading
 import tkinter as tk
 
@@ -6,6 +8,7 @@ import config
 from .mainwindow import MainWindow
 from .boardview import BoardView
 from .settings import Settings
+from util import exportBoard
 
 log=logging.getLogger(__name__)
 
@@ -23,6 +26,8 @@ class GUI:
 		self._coreMessages=None
 
 		self._state=GUI.SETUP
+		self._board=[]
+		self._filename=""
 
 		self.mainWindow = MainWindow(self, master=self.root)
 		self.settings=None
@@ -33,6 +38,7 @@ class GUI:
 		self.root.bind("<<setUp>>", lambda e: self.setUp())
 		self.root.bind("<<setRecording>>", lambda e: self.setRecording())
 		self.root.bind("<F12>",lambda e: Settings(self))
+		self.root.bind("s",lambda e: self._save())
 		self.mainWindow.bind("<Destroy>",lambda e: self._ownMessages.send("!kill",("gui",)))
 
 		self.setUp()
@@ -62,6 +68,18 @@ class GUI:
 			self.settings.destroy()
 			self.settings=None
 
+	def _save(self):
+		board=exportBoard(self._board)
+		corners=[[p.x,p.y] for p in self.mainWindow.imgView.exportCorners()]
+		res={
+			self._filename: {
+				"board": board,
+				"corners": corners
+			}
+		}
+		with open(os.path.join(config.misc.imgDir,self._filename+".json"), mode="wt") as f:
+			json.dump(res,f,indent="\t")
+
 	def _handleEvent(self,e):
 		actions={
 			"setCurrentFrame": self._frameHandler,
@@ -72,13 +90,15 @@ class GUI:
 
 		return actions[actionName](*args,**kwargs)
 
-	def _frameHandler(self,newFrame,type):
+	def _frameHandler(self,newFrame,type,filename):
 		if self._state!=type: return
+		self._filename=filename
 		self.mainWindow.setCurrentFrame(newFrame)
 		self.root.event_generate("<<redrawImgView>>")
 
 	def _stateHandler(self,gameState,moves):
 		labels={(row,col):(i+1) for (i,(c,row,col)) in enumerate(moves)}
+		self._board=gameState
 		self.mainWindow.boardView.redrawState(gameState,labels)
 
 	def _paramsHandler(self,**params):
diff --git a/src/gui/imgview.py b/src/gui/imgview.py
--- a/src/gui/imgview.py
+++ b/src/gui/imgview.py
@@ -31,7 +31,9 @@ class ImgView(ResizableCanvas):
 		self.delete("all")
 
 		if self._img:
-			img=self._img.resize((int(self._width),int(self._height)))
+			w,h=self._img.size
+			ratio=min(self._width/w, self._height/h)
+			img=self._img.resize((int(w*ratio),int(h*ratio)))
 			self._tkImg=ImageTk.PhotoImage(img) # just to save the image from garbage collector
 			self.create_image(self._width//2, self._height//2, anchor="center", image=self._tkImg)
 
@@ -65,8 +67,7 @@ class ImgView(ResizableCanvas):
 			# transform corners from show coordinates to real coordinates
 			log.debug(self._corners.corners)
 			self._boardGrid=Grid(self._corners.corners)
-			corners=[self._transformPoint(c) for c in self._corners.corners]
-			self._parent.sendMsg("setCorners",(corners,))
+			self._parent.sendMsg("setCorners",(self.exportCorners(),))
 
 		self.redraw()
 
@@ -75,6 +76,9 @@ class ImgView(ResizableCanvas):
 		self.create_line(x-3,y-3,x+4,y+4,fill="#00ff00")
 		self.create_line(x-3,y+3,x+4,y-4,fill="#00ff00")
 
+	def exportCorners(self):
+		return [self._transformPoint(c) for c in self._corners.corners]
+
 	def setUp(self):
 		self.bind('<1>',lambda e: self.addCorner(e.x,e.y))
 
@@ -95,7 +99,7 @@ class ImgView(ResizableCanvas):
 		wo,ho=self._img.size # o for original
 		widthRatio=wo/w
 		heightRatio=ho/h
-		self._imgSizeCoef=max(widthRatio,heightRatio)
+		imgSizeCoef=max(widthRatio,heightRatio)
 		# shift compensates possible horizontal or vertical empty margins from unmatching aspect ratios
-		self._imgShift=EPoint(wo-w*self._imgSizeCoef,ho-h*self._imgSizeCoef)/2
-		return EPoint(self.canvasx(point.x),self.canvasy(point.y)) * self._imgSizeCoef + self._imgShift
+		imgShift=EPoint(wo-w*imgSizeCoef,ho-h*imgSizeCoef)/2
+		return EPoint(self.canvasx(point.x),self.canvasy(point.y)) * imgSizeCoef + imgShift