  Color intensity projections (CIP) have been shown to improve the
visualisation of greyscale angiography images by combining greyscale images
into a single color image. A key property of the combined CIP image is the
encoding of the arrival time information from greyscale images into the hue of
the color in the CIP image. A few minor improvements to the calculation of the
CIP image are introduced that substantially improve the quality of the
visualisation. One improvement is interpolating of the greyscale images in time
before calculation of the CIP image. A second is the use of hue cycling - where
the hue of the color is cycled through more than once in an image. The hue
cycling allows the variation of the hue to be concentrated in structures of
interest. If there is a zero time point hue cycling can be applied after zero
time and before zero time can be indicated by greyscale. If there is an end
time point hue cycling can be applied before the end time and pixels can be set
to black after the end time. An angiogram of a brain is used to demonstrate the
substantial improvements hue cycling brings to CIP images. A third improvement
is the use of maximum intensity projection for 2D rendering of a 3D CIP image
volume. A fourth improvement allowing interpreters to interactively adjust the
phase of the hue via standard contrast - brightness controls using lookup
tables. Other potential applications of CIP are also mentioned.
