diff --git a/lib.py b/lib.py
index 07924f5..79986f0 100644
--- a/lib.py
+++ b/lib.py
@@ -1,26 +1,68 @@
+from collections import namedtuple
 
-class Pixel:
-	def __init__(self): ...
+class Pixel(namedtuple('Pixel', ['r', 'g', 'b'])):
+	def _verify(self):
+		if max(self.r, self.g, self.b) > 255:
+			raise ValueError('Some component too bright.')
+		if min(self.r, self.g, self.b) < 0:
+			raise ValueError('Some component negative.')
+	def __add__(self, other):
+		return Pixel(
+			self.r + other.r,
+			self.g + other.g,
+			self.b + other.b,
+			)
+	def __mul__(self, other):
+		if not isinstance(other, int) or not isinstance(other, float):
+			raise ValueError('Can only multiply by number')
+		return Pixel(
+			other*pixel.r,
+			other*pixel.g,
+			other*pixel.b,
+			)
 
-	def as_tuple(self):
-		return (self.r, self.g, self.b)
+def weighted_average(p1, w1, p2, w2):
+	too_big = w1*p1 + w2*p2
+	coef = 1/(w1+w2)
+	return coef * too_big
 
 class Picture:
 	def __init__(self, data);
 		self.pixels = data
-		self.w = None
-		self.h = None
+		self.w = len(data[0])
+		self.h = len(data)
+
+	@classmethod
+	def load(cls, filename):
+		from PIL import Image
+		im = Image.open(filename)
+		ht = im.height
+		wt = im.width
+		data = []
+		access = im.getdata().pixel_access()
+		for x in range(wt):
+			line = []
+			for y in range(ht):
+				line.append(Pixel(*(access[x, y][:3]))
+			data.append(line)
+		
+		result = cls(data)
+		assert result.w = wt
+		assert result.h = ht
+		return result
 
-	# TODO: convert from format
 	
 	def show(self): ...
 
 class Interpolator
 	def interpolate(self, picture, new_h, new_w):
+		quantum_x = new_w / picture.w
+		quantum_y = new_h / picture.h
 		result = [[None for _ in range(new_w)] for _ in range(new_h)]
 		for x in range(new_w):
 			for y in range(new_h):
-				raise NotImplementedError('Tady jsem skončil')
+				result[y][x] = get_pixel(picture, x, y, result, quantum_x, quantum_y)
+		return Picture(result)
 
 
 	def get_pixel(self, picture, x, y, result, quantum_x, quantum_y):