Autochromatic 

Autochromatic is a Photoshop plugin for creating duotone, sepia and color tint effects. It can add a rust or lavender tone, create psychedelic color effects, and helps you select and tone the colors in your image to suit your website's color scheme.
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PhotoKit Color 

PhotoKit Color is a Photoshop Plug-in that applies precise color corrections, automatic color balancing and creative coloring effects. PhotoKit Color offers a set of coloring tools for Photoshop (7.0, CS and CS2) for both Macintosh and Windows.
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PixTwix 

PixTwix is an image processing ActiveX control featuring over 150 methods for manipulation and enhancement of images, special effects and filters, layer blending, selection routines and more. PixTwix can read and write many popular image formats.
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