Through most of the 1950s he was in high demand for his creative advertising work that featured striking visual images and intense colors.
[2] During this time he began creating a series of highly distinctive nudes that used the Sabattier effect to meld form and surface together.
His involvement led him to explore the chemistry and mechanics of the offset process in detail, and he experimented at length by doing such things as changing the patterns of the printing dots and overprinting images with multiple colors to achieve extraordinary saturation.
In an interview in the late 1970s Walker said, "The contact with the ideas of the printmaker have greatly altered my attitudes toward photography, and how each discipline deals with an image.
With these techniques he was able to create digital works that blurred, inverted and obscured the original image, making it into an expressive rather than detailed representation of reality.