image_pattern
// pattern for use in texture/pigment/normal/density
// takes the color of an image file to calculate the pattern value
image_pattern {
png plasma3.png // image file to read (iff/tga/gif/png/jpeg/tiff/sys)
//use_color // use pixel color gray scale (default)
//use_alpha // use alpha value
//use_index // use palette index
}