A few grayscale de-skew implementations exist in document imaging applications.
Picture Elements has ASIC and board designs modifiable for special-purpose grayscale de-skew applications.
The Picture Elements Imaging Subsystem Engine tm (ISE tm) is a PCI bus board which incorporates real-time grayscale de-skew along with grayscale scaling, JPEG, Group 4 and JBIG compression, high-quality thresholding and interfacing to high-performance scanners.
The BancTec S-Series scanners incorporate grayscale de-skew as a hardware option.
The latest generation of BancTec check scanners incorporate grayscale de-skew for lower cost and greater feed reliability.