diff --git a/jpegObj/__init__.py b/jpegObj/__init__.py
index fda3eef..8e5ecab 100644
--- a/jpegObj/__init__.py
+++ b/jpegObj/__init__.py
@@ -53,7 +53,7 @@ class Jpeg(Jsteg):
         Jsteg.__init__(self, file, **kw)
         self.verbosity = verbosity
         if verbosity > 0:
-            print "[jpeg.__init__] Image size %ix%i" % (self.coef_arrays[0].shape)
+            print "[Jpeg.__init__] Image size %ix%i" % (self.coef_arrays[0].shape)
         if key != None:
             self.key = key
         elif rndkey:
@@ -187,13 +187,40 @@ class Jpeg(Jsteg):
         cID = self.getCompID(channel)
         return self.coef_arrays[cID]
 
+    def setCoefMatrix(self, matrix, channel="Y"):
+        v, h = self.getCoefMatrix(channel).shape
+        assert matrix.shape == (v, h), "matrix is expected of size (%d,%d)" % (v, h)
+
+        cID = self.getCompID(channel)
+        self.coef_arrays[cID] = matrix
+
+
     def getCoefBlocks(self, channel="Y"):
         """
           This method returns the coefficient matrix for the given
           colour channel (as a 4-D tensor: (v,h,row,col)).
         """
+        if channel == "All":
+            return [
+                np.array([np.split(arr, arr.shape[1] / 8, axis=1) for arr in np.split(compMat, compMat.shape[0] / 8)])
+                for compMat in self.coef_arrays]
+
         compMat = self.getCoefMatrix(channel="Y")
-        return np.array([np.split(arr,arr.shape[1]/8, axis=1) for arr in np.split(compMat,compMat.shape[0]/8)])
+        return np.array([np.split(arr, arr.shape[1] / 8, axis=1) for arr in np.split(compMat, compMat.shape[0] / 8)])
+
+    def getCoefBlock(self, channel="Y", loc=(0, 0)):
+        """
+          This method returns the coefficient matrix for the given
+          colour channel (as a 4-D tensor: (v,h,row,col)).
+        """
+        return self.getCoefBlocks(channel)[loc]
+
+
+    def setCoefBlock(self, block, channel="Y", loc=(0, 0)):
+        assert block.shape == (8, 8), "block is expected of size (8,8)"
+        cID = self.getCompID(channel)
+        v, h = loc[0] * 8, loc[1] * 8
+        self.coef_arrays[cID][v:v + 8, h:h + 8] = block
 
     # Decompression
     # -------------
diff --git a/jpegObj/__init__.pyc b/jpegObj/__init__.pyc
index b8044a9..b39a44c 100644
Binary files a/jpegObj/__init__.pyc and b/jpegObj/__init__.pyc differ
diff --git a/yaj.py b/yaj.py
index 76b487a..5a10101 100644
--- a/yaj.py
+++ b/yaj.py
@@ -1,41 +1,28 @@
 __author__ = 'chunk'
 
-# import mjsteg
 import numpy as np
-
-# a = mjsteg.Jsteg("res/test2.jpg")
-# compY,compCr,compCb = a.coef_arrays
-#
-# res =  np.array([np.split(arr,arr.shape[1]/8, axis=1) for arr in np.split(compY,compY.shape[0]/8)])
-#
-# print res.shape
-#
-# print res[0,0:20]
-
 import jpegObj
 
 b = jpegObj.Jpeg("res/test2.jpg")
-c =  b.getCoefBlocks(channel='Y')
-
-print c
-print c.shape
-
-
-
-
-
-
-
-
-
-
-
+# c =  b.getCoefBlocks(channel='Y')
+# c1,c2,c3 =  b.getCoefBlocks(channel='All')
+# print c2
 
 
+print b.setCoefBlock(np.array([[0] * 8 for i in range(8)]))
 
+c = b.getCoefBlock(channel='Y', loc=(0, 0))
+print c
 
+c = b.getCoefBlock(channel='Y', loc=(-1, 1))
+print c
 
+b.setCoefMatrix(np.array([[0] * 800 for i in range(600)]),channel='Y')
 
+c = b.getCoefBlock(channel='Y', loc=(-1, 1))
+print c
 
+c = b.getCoefBlock(channel='Y', loc=(0, 0))
+print c
 
 
--
libgit2 0.21.2