====== Transforming Images (Applying Rotation, Translation, Scale and Mirroring) ======

What follows is a very simply demonstration of using the Transform object to transform EMData (image) objects. A very thorough explanation of using the Transform is presented in [[Eman2TransformInPython|Using the EMAN2 Transform class]] and you are encouraged to at least be aware of that page's existence.

===== Using EMData.transform =====

The first example here is a **3D** example.

<code>#!python
[someone@localhost]# e2.py

Welcome to EMAN2
Prompt provided by IPython
Enter '?' for ipython help


In [3]:  e = test_image_3d() # 3D test image

In [4]:  t = Transform({"type":"eman","az":45,"alt":90})

In [5]:  t.set_trans(1,-2,5)

In [6]:  t.set_scale(2.0)

In [7]:  e.transform(t)

In [8]:  display(e)

</code>

This second example is a **2D** example.

<code>#!python

In [9]:  e = test_image() # This is a 2D test image

In [10]:  t = Transform({"type":"2d","alpha":45}) # Note 2D terminology

In [11]:  t.set_trans(3,-2) # Note 2D translation

In [12]:  t.set_mirror(True)

In [13]:  e.transform(t)

In [14]:  display(e)

</code>


===== Using the Processor Framework =====

You can use the processor framework to process an EMData object in and out of place. This can be useful when you wish to operate on a copy of the original image, as opposed to altering it.

<code>#!python

In [15]:  t = Transform(....) # Construct a transform as above

In [16]:  out_of_place = e.process("xform",{"transform":t}) # Out of place

In [17]:  e.process_inplace("xform",{"transform":t}) # Inplace

In [18]:  e.transform(t) # exactly the same as line above

</code>