About Debarrelizer
Debarrelizer is a plug-in for Photoshop to correct barrel distortion and chromatic aberration in images

Disclaimer: This software is provided "as is". No warranties of any kind, expressed or implied, are given. Not even to its functionality, use and applicability. Read the License agreement for further information.

Contents of this Read-me file:
1. Installation
2. Distortion angle
3. Chromatic aberration
4. Preview
5. Known issues and incompatibilities

1. Installation
Move or Copy the filter plug-in to your Photoshop filters folder, (re)start Photoshop, then the filter should be available under:

filter --> Digital Imaging Tools --> Debarrelizer...

2. Distortion angle
When capturing an image through a lens, the light representing the image hits the curved lens surface. For non-fisheye lenses, the image at the curved lens surface is then supposed to be projected rectilinear at the film or capturing surface. Most high-end, expensive lenses will do this correctly. However, for non-high-end lenses and zoom lenses (especially those used in the point and shoot digital cameras) this usually is not completely corrected.

The value entered under distortion angle is the "angle" that still needs to be corrected.

This value is taken to be the horizontal angle. So, if you want to correct true fisheye images, make sure the horizontal plane doesn't extend beyond the image data.

Note: the distortion resulting from too little correction is called "barrel distortion". In zoom lenses there sometimes occurs too much correction, which results in the opposite effect called "pin-cushion distortion". Debarrelizer currently does NOT correct pin-cushion distortion...

3. Chromatic aberration
As white light passes glass diffraction occurs which bends off the different colors in the light in a slightly different angle. This prism effect also occurs in lenses, and is called chromatic aberration. The result can be seen in the different color channels of an RGB image. Switching between the different channels makes the image appear slightly smaller or larger. The effect is most noticable at the far edges of the image.
Debarrelizer allows you to correct this effect during the debarrelizing process. The Red channel and Blue channel can be "synchronized" with the Green channel.

The value entered under R offset and B offset is the size in pixels that the corresponding channel needs to be "scaled" to fit the Green channel.

4. Preview
A preview is available for a quick assesment of the correct value for the distortion angle parameter. Be aware that this only is a preview and that a monitor tube usually suffers barreldistortion or pincushion distortion itself. (The new 17" Studio displays with flat-vision correction, for example, suffers mild pincushion distortion!)

5. Known issues and incompatibilities
If you find anything not working as you would expect, let us know at dbrl@theimagingfactory.com

Questions, suggestions, comments and other issues regarding this product can be send by e-mail to dbrl@theimagingfactory.com. For general information regarding our products you can visit our web-site at www.theimagingfactory.com or e-mail us at info@theimagingfactory.com.