DISTORTION
 
Distortion Correction or Keystone Correction are the technical terms we use to describe the process of ensuring that an image projects squarely even if the projector is positioned vertically and/or horizontally off-centre.  
 
The degree to which the image needs to be corrected will depend on how far the light source is from the projection surface and the obliqueness of the angle(s) at which the image will be projected.  Provided Rosco is given these two pieces of information we can calculate the shape of the image which will need to be reproduced on the gobo.  As you might expect this can be a time consuming process, depending on the complexity of the image, so we do make a nominal charge per design.

Standard image projected square on	Standard image projected off horizontal axis	Standard image projected off horizontal & vertical axes	CORRECTED image projected off axis

IMAGE SIZING
 
There are many occasions on which designers need their final projected image to be of a certain size irrespective of how far the light source is from the projection surface.  In these instances, if you give Rosco details of the lantern and the distance it will be set from the projection surface, we can calculate what size the image needs to be on the gobo itself.