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<p><b>New page</b></p><div>'''Stitching 2008 State of the Art'''<br />
<br />
== Introduction ==<br />
<br />
Stitching is about making one large image from several smaller photos.<br />
The ambition is to have the fact of individual ingredient photos no longer show through in the resulting image.<br />
This page shows what stitching software actually does.<br />
<br />
If you want to know how to achieve this, or what<br />
[[software]] to use, please read a [[Tutorials|tutorial]] instead.<br />
What can be done and what quality can be achieved,<br />
this shall be demonstrated step by step starting with the two photos below.<br />
<br />
[[Image:Img08232.jpg|300px]] [[Image:Img08231.jpg|300px]]<br />
<br />
At the time of photography, some [[Photography Guidelines|guidelines]] have been followed that make the photos good stitching material.<br />
<br />
----<br />
<br />
For comparison to stitching proper, the two photos have simply been overlayed in a standard<br />
image editing and retouching software. <br />
<br />
[[Image:Img0823xoverlay1.jpg|300px]] [[Image:Img0823xoverlay2.jpg|300px]]<br />
<br />
Please notice in particular the misalignment of geometrical features in the left image,<br />
and the roof misorientation in the right one.<br />
<br />
----<br />
<br />
Have a look at the following aspects to see where proper stitching software can do better.<br />
Such software usually gives a choice of either performing these steps fully automatically,<br />
or provide assistance for optimisations without requiring a try-and-error workflow.<br />
<br />
===Remapping===<br />
<br />
[[Image:Img08232remap.jpg|300px]] [[Image:Img08231remap.jpg|300px]]<br />
<br />
To project the images onto the same virtual screen, they need<br />
to be remapped, as shown above. Correcting falling lines as in this example<br />
is by choosing an appropriate orientation for the virtual screen.<br />
<br />
[[Image:Img0823xstitch3.jpg|500px]]<br />
<br />
The relative camera orientation, and the lense parameters<br />
are determined from the images overlap area.<br />
Handheld photos are fine.<br />
If the photos have been taken from the same point,<br />
expect alignment accuracy of better than a pixel.<br />
<br />
===Exposure===<br />
<br />
[[Image:Img0823xstitch4.jpg|500px]]<br />
<br />
Input images need not have the same exposure, or white balance.<br />
Together with vignetting<br />
(images are darker in the corners than in the middle)<br />
the required corrections<br />
can be derived from images with a suitably large overlap area.<br />
<br />
===Blending===<br />
<br />
Obviously, there needs to be some kind of seam between the images,<br />
but one can do better than a hard seam line (used above)<br />
or a feathered transition that affects the image character.<br />
<br />
[[Image:Img0823xstitch5.jpg|500px]]<br />
<br />
State of the art is a seam mechanism that behaves<br />
like a line for small details but averages for large scale features.<br />
<br />
[[Image:Img0823xstitch6.jpg|500px]]<br />
<br />
In addition, the seam line should be placed intelligently<br />
to avoid cutting through objects (like cloud, car or bicycle)<br />
that have moved in the time between taking the images.<br />
<br />
==Overall Result==<br />
<br />
[[Image:Img0823xstitch6crop.jpg|600px]]<br />
<br />
This is the overall result, cropped to rectangular shape,<br />
for a state-of-the-art stitching of two photos.<br />
<br />
==Further Reading==<br />
Some quick pointers to continue in the general panotools wiki space:<br />
* [[Photography guidelines]] - at the time of taking photos<br />
* [[Stitching]] - the [[How stitching works]] may look familiar :)<br />
* Panorama viewing<br />
and more general pages<br />
* [[Software]]<br />
* [[Tutorials]]<br />
Happy browsing here in the panotools wiki.</div>Klaus