Method for operating an image generator, an image generator, a method for generating digital colour image data and a display system

A method for generating digital colour image data for a digital display using output by an image generator arranged to generate and to output signals for displaying image elements of a predefined set of image elements, each image element being defined by respective varying deflection signals, the image generator configured to define a colour change trigger, the colour change trigger comprising an additional image element defined by varying deflection signals different to varying deflection signals of an image element of the predefined set, and the image generator further configured to generate and output the varying deflection signals of the defined colour change trigger thereby to indicate a respective colour for use in displaying an image element of the predefined set, the method comprising:

• receiving varying deflection signals output by the image generator;
• determining the deflection directions represented by the received varying deflection signals;
• recognising, from selected combinations of the determined deflection directions, a respective colour change trigger, thereby to determine a colour indicated by the recognised colour change trigger;
• and
• converting the received varying deflection signals into image data defining pixels in a digital display device for displaying a respective image element with the indicated colour.