.. realign


.. _internal_realign:


Re-Align Image
==============

Many times a plot from an old PDF or report contains images that are rotated or distorted in the photo-copy process.  In order to realign the axes and make them orthogonal, use the ``Fix-Image-Alignment`` option.

3 and 4 Point Alignment
-----------------------

The images below, for example, need to be realigned before they can be digitized.  The image on the left has 4 distinct corners that can be used to realign the axes. The image on the right, has only 3 distinct points.

Under the menu option ``Fix-Image-Alignment``, you can choose ``4 Point Axes Align`` or ``3 Point Axes Align`` as appropriate.

.. raw:: html

    <table border="1">
    <tr>
    <th>4 Point ReAlign</th>  <th>3 Point ReAlign</th></tr>
    <tr>
        <td> 
            <a  href="./_static/misaligned_img.jpg">
            <img src="./_static/misaligned_img.jpg">
            </a>
        </td>
        <td> 
            <a  href="./_static/misaligned_img_3pt.jpg">
            <img src="./_static/misaligned_img_3pt.jpg">
            </a>
        </td>
    </tr>
    </table>

`Click images to see full size`

Click Reference Points
----------------------

Follow the on-screen prompts and click the reference corners (3 or 4).

.. raw:: html

    <table border="1">
    <tr>
    <th>Click Xmin</th><th>Click Xmax</th><th>Click Ymin</th><th>Click Ymax</th></tr>
    <tr>
        <td> 
            <a  href="./_static/UL_click.jpg">
            <img src="./_static/UL_click.jpg">
            </a>
        </td>
        <td> 
            <a  href="./_static/UR_click.jpg">
            <img src="./_static/UR_click.jpg">
            </a>
        </td>
        <td> 
            <a  href="./_static/LR_click.jpg">
            <img src="./_static/LR_click.jpg">
            </a>
        </td>
        <td> 
            <a  href="./_static/LL_click.jpg">
            <img src="./_static/LL_click.jpg">
            </a>
        </td>
    </tr>
    </table>


`Click images to see full size`

Verify Results
--------------

When done, verify results with cross-hairs (i.e. verify orthogonal axes).


.. raw:: html

    <table border="1">
    <tr>
    <th>Say OK</th>  <th>Verify Results</th></tr>
    <tr>
        <td> 
            <a  href="./_static/align_OK_popup.jpg">
            <img src="./_static/align_OK_popup.jpg">
            </a>
        </td>
        <td> 
            <a  href="./_static/post_align_check.jpg">
            <img src="./_static/post_align_check.jpg">
            </a>
        </td>
    </tr>
    </table>