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Unwarping images using ArcMap: Home

This guide shows how to use ArcMap to transform an image of a curled book into a flat picture. Scanned images of books are often distorted near the binding. This process can correct for that.

Introduction - Unwarping Images

When taking pictures or scans of books, there may be times that the book can’t be opened fully and the resulting image shows a curve.  The georeferencing tool in ArcMap can transform the image into a flat view.  Other tools that have image warping capabilities include Java Image Editor's warp tool http://www.jhlabs.com/ie/warp_tool.html and Photoshop's transform tool.

ArcMap with its control points can give precise adjustment to smooth a wrinkled page.  

This picture of an early manuscript is an example of a curled and wrinkled page.   

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 http://www.flickr.com/photos/nationallibrarynz_commons/5352531963/sizes/o/in/photostream/

 http://www.flickr.com/photos/nationallibrarynz_commons/5352531963/

After transformation it is not quite as warped.

 

If possible, take precise measurements of the size and spacing of the text.  It can help in placing points at the proper locations on the grid.  In this example, we don’t know the actual dimensions of the text, so we will assume that the lines are evenly spaced and try to approximate the solution.

In ArcMap, we will import the image, add a guiding grid, transform the image and then save it.

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