# HG changeset patch
# User ychherawala@smets-w04
# Date 1265122803 18000
# Node ID e61a46996db68f32a85c8950c7ba249b093d2d8b
# Parent  6d432a5010a29d475b52e3601f9320849a0c8486
first commit, the module has been tested with testmod.py, it has no timing

diff -r 6d432a5010a2 -r e61a46996db6 transformations/slant.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/transformations/slant.py	Tue Feb 02 10:00:03 2010 -0500
@@ -0,0 +1,96 @@
+#!/usr/bin/python
+# coding: utf-8
+
+'''
+this module add a slant effect to the image. 
+
+To obtain the slant effect, each row of the array is shifted proportionately by a step
+controlled by the complexity.
+
+'''
+
+import numpy
+
+
+class Slant():
+    def __init__(self, complexity=1):
+        #---------- private attributes
+        self.direction = 1
+        self.angle = 0
+
+        #---------- generation parameters
+        self.regenerate_parameters(complexity)
+        #------------------------------------------------
+    
+    def _get_current_parameters(self):
+        return [self.angle, self.direction]
+    
+    def get_settings_names(self):
+        return ['angle', 'direction']
+    
+    def regenerate_parameters(self, complexity):
+        self.angle = numpy.random.uniform(0.0, complexity)
+        P = numpy.random.uniform()
+        self.direction = 1;
+        if P < 0.5:
+            self.direction = -1;
+        return self._get_current_parameters()
+    
+    
+    def transform_image(self,image):
+        if self.angle == 0:
+            return image
+        
+        ysize, xsize = image.shape
+        slant = self.direction*self.angle
+
+        output = image.copy()
+
+        # shift all the rows
+        for i in range(ysize):
+            line = image[i]
+            delta = round((i*slant)) % xsize
+            line1 = line[:xsize-delta]
+            line2 = line[xsize-delta:xsize]
+
+            output[i][delta:xsize] = line1
+            output[i][0:delta] = line2
+
+            
+        #correction to center the image
+        correction = (self.direction)*round(self.angle*ysize/2)
+        correction = (xsize - correction) % xsize
+
+        # center the region
+        line1 = output[0:ysize,0:xsize-correction].copy()
+        line2 = output[0:ysize,xsize-correction:xsize].copy()
+        output[0:ysize,correction:xsize] = line1
+        output[0:ysize,0:correction] = line2
+
+
+        return output
+            
+
+# Test function
+def test_slant():
+    img_name = "3.png"
+    dest_img_name = "slanted.png"
+    im = Image.open(img_name,)
+    im = im.convert("L")
+    image = numpy.asarray(im)
+
+
+    slant = Slant()
+    slant.regenerate_parameters(1)
+    image = slant.transform_image(image)
+
+    im = Image.fromarray(image.astype('uint8'), "L")
+    im.save(dest_img_name)
+
+# Test
+if __name__ == '__main__':  
+    import sys, os, fnmatch
+    import Image
+
+    test_slant()
+