diff --git a/ddresc_visu/draw.py b/ddresc_visu/draw.py
index d43f4ab..f29914d 100644
--- a/ddresc_visu/draw.py
+++ b/ddresc_visu/draw.py
@@ -13,11 +13,11 @@ colors = {
 
 BORDERCOLOR = (64,64,64)
 
-W = 1920
-H = 1080
-CELLSIZE = 4
+W = 1920 * 2 // 3
+H = 1060
+CELLSIZE = 8
 CELLBORDER = 0
-CELLMARGIN = 2
+CELLMARGIN = 3
 
 CELLOFFSET = CELLSIZE + 2*CELLBORDER + CELLMARGIN
 COLUMNS = W // CELLOFFSET
@@ -36,11 +36,11 @@ def get_symb(hist):
 			return ch
 
 class Visualisation:
-	def __init__(self, fn):
+	def __init__(self, fn, **kwargs):
 		pygame.init()
 		self.disp = pygame.display.set_mode((W, H))
 
-		self.mapfile = MapFile(fn)
+		self.mapfile = MapFile(fn, **kwargs)
 		self.mapfile.load()
 
 	def draw(self):
diff --git a/ddresc_visu/mapfile.py b/ddresc_visu/mapfile.py
index 80e9475..e940384 100644
--- a/ddresc_visu/mapfile.py
+++ b/ddresc_visu/mapfile.py
@@ -29,28 +29,49 @@ def read_mapfile(fn):
 
 
 class MapFile:
-	def __init__(self, filename):
+	def __init__(self, filename, start=None, end=None):
 		self.mapfilename = filename
+		self.start = start
+		self.end = end
 	
 	def load(self):
 		self.status, self.blocks, self.comments = read_mapfile(self.mapfilename)
+		if self.start is not None or self.end is not None:
+			self.filter_data()
 		self.size = max(map(lambda blk: blk[0]+blk[1], self.blocks))
 	
+	def filter_data(self):
+		assert self.start is not None and self.end is not None
+		self.blocks = self.filter_blocks(self.blocks, self.start, self.end)
+		self.blocks = self.trim_blocks(self.blocks, self.start, self.end)
+		
+		# Move blocks:
+		self.status = tuple([self.status[0] - self.start, *self.status[1:]])
+		nblocks = []
+		for blk in self.blocks:
+			nblk = tuple([blk[0] - self.start, *blk[1:]])
+			nblocks.append(nblk)
+		self.blocks = nblocks
+
+	
 	def get_state(self, pos):
 		# TODO: this is lame
 		for blk in self.blocks:
 			if pos >= blk[0] and pos < blk[0] + blk[1]:
 				return blk[2]
-
-	def get_hist(self, start, end):
+	
+	@staticmethod
+	def filter_blocks(blocks, start, end):
 		relevant_blocks = []
-		for blk in self.blocks:
+		for blk in blocks:
 			if start < blk[0] + blk[1] and end >= blk[0]:
 				relevant_blocks.append(blk)
+		return relevant_blocks
 
-		# Trimming:
+	@staticmethod
+	def trim_blocks(blocks, start, end):
 		trmblks = []
-		for blk in relevant_blocks:
+		for blk in blocks:
 			bg, lt, symb = blk
 			if bg < start:
 				lt -= start - bg
@@ -58,6 +79,12 @@ class MapFile:
 			if bg + lt > end:
 				lt -= bg+lt - end
 			trmblks.append((bg, lt, symb))
+		return trmblks
+
+	def get_hist(self, start, end):
+		relevant_blocks = self.filter_blocks(self.blocks, start, end)
+
+		trmblks = self.trim_blocks(relevant_blocks, start, end)
 
 		# Grouping by symbols:
 		grp = {}
diff --git a/test.py b/test.py
index 4093b96..8d6e08b 100755
--- a/test.py
+++ b/test.py
@@ -1,9 +1,10 @@
 #!/bin/python3
 import ddresc_visu.draw as v
 from time import sleep
+import argparse
 
 FILE = '/mnt/TAP9701/2021-08-11_Pm_ddresc_mapfile'
-visu = v.Visualisation(FILE)
+visu = v.Visualisation(FILE, start=1000**3, end=30*1000**3)
 
 def redraw():
 	visu.reload()