Guide to CITE Extensions: home page.
CHS Images: extended citation
The CHS Image Extension allows a CITE URN to be qualified by a scale-independent image subreference identifying a region of interest (RoI).
The region of interest is expressed as four comma-delimited values ranging from 0 <= n < 1.0. The four values are therefore independent of any scale of reproduction of the image.
The four values are:
- initial x position (left edge)
- initial y position (top edge)
is a CITE URN identifying an image in the
chsimg collection within the namespace identified by the abbreviation
The top left quarter of this image could be cited with the URN
The first two values of the RoI indicate that the cited region begins at the left, top edge of the image (0,0); the third value means that the cited region extends for 50% of the width of the image (0.5), and the fourth value means that the cited region extends for 50% of the height of the image (0.5).
To visualize how these RoI references work, it can be helpful to try out values in an image service such as the one at amphoreus.hpcc.uh.edu/tomcat/chsimg/requests.