This plug-in combines the functions of the old Whirl and Pinch plug-ins. It distorts the image by whirling and pinching, which are two common center-based, circular distortions. Whirling is like projecting the image onto the surface of water in a toilet and flushing. Pinching is similar to projecting the image onto an elastic surface and pressing or pulling on the center of the surface.

This plug-in uses the algorithm described by John Schlag, ``Fast Embossing Effects on Raster Image Data'' in Graphics Gems IV (ISBN 0-12-336155-9). It takes an image to be applied as a bump map to another image, producing a nice embossing effect.

This simple plug-in does an automatic contrast stretch. For each channel in the image, it finds the minimum and maximum values, and uses that information to stretch the individual channels' histograms to the full contrast range. For some images it may do just what you want; for others it may be total crap. If the latter, you may want to consider using the Normalize plug-in by Adam Moss.

When an image is taken from a video capture source (f.i. a freeze-frame), sometimes only either the odd or the even fields in the frame get captured, resulting in an image which, line by line, is data-black-data-black-etc. This plug-in does a simple interpolation between the odd or even fields in an image to correct this.

This plug-in does the well-known `page curl' effect. It is like when you curl one of the corners of a sheet of paper.

This plug-in does a histogram equalization of the image. That is, it modifies the image's histogram so that it is approximately horizontal, so that all intensity values cover about the same number of pixels in the image (i.e. the histogram is well-balanced).