Image processing

Document Deskewer
The Document Deskewer is a simple and easy to use command-line tool for automatically correcting skewed pages. Given a skewed input image the tool detects the skew angle and automatically corrects the rotation for the full range of 0-360 degrees. The processing can be adjusted using parameters which allow the user to select the resampling method or the colour used to fill blank areas introduced by the image rotation.Read more

Geometric Correction: Page Curl
The Page Curl Correction is a command-line tool capable of detecting such distortions and correcting them automatically. This can significantly improve the results of a subsequent text recognition step since most OCR algorithms neglect this kind of distortion.Read more

GIMP
GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. GIMP is best known as a free alternative to professional graphic editing programs such as Adobe Photoshop. However it also includes a batch mode that allows you to perform image processing tasks from the command line and to easily apply the same set of operations to a number of images. Read more

ImageMagick / GraphicsMagick
ImageMagick is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 100) including DPX, EXR, GIF, JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF Read more.

Scan Tailor
Scan Tailor is an interactive tool for post-processing of scanned pages. It gives the ability to cut or crop pages, compensate for skew angle, and add / delete content fields and margins, among others. Read more