General model of light-to-light television and related imaging systems
Current television or any other related non-adaptive image systems can be presented in accordance with the scheme, depicted on the Figure 1.1, where the system is presented as a series connection of light-signal transformer (camera), electrical transmission path and signal-light transformer (reproducing device).
In the electrical path of TV-system, transmitted color is expressed with the primary signals or luminance and colour difference signals. These signals can be considered as coordinates of the three-dimensional color space of system.
Transition “light-signal” and “signal-light” in the terminal devices may be presented as the transition from (for example ) color space coordinates tothe signals (for example or ) at the transmitting side and as the transition from the signals to coordinates of reproduced image color space on the receiving side.
Figure 1.2 is a block diagram of an adaptive image system, providing color reproduction, independent on used devices (regarding colorimetric transformations, realized in them) and on the shooting object observation conditions at the transmitting side and reproduced image on the receiving side, is given. The principal distinction of such a system from non-adaptive system consists in using color space in the transmitting environment independent of the colorimetric transformations in devices used and from observation conditions.
For color reproduction quality assessment in uniform color space, in which shooting object visual perception is associated with the coordinates of this colour space at the transmitting side, and reproduced image visual perception is associated with color coordinates, on the receiving side may be used. As coordinates color spaces coordinates, expressed with different degree of adequacy to the human vision characteristics, may be used. As such color spaces the CIE developed spaces CIELUV, CIELAB, CIECAM02 may be used. As a measure of color reproduction quality in such case with a certain degree of conditional character distance in the space may be used.
In multimedia applications, the principle of device independent images transmission can be realized by means of ICC profile use [1.1, 1.2], which in colorimetry literature is expanded to principle of viewing independent transmission principle.
For television applications such principles are described in [1.3‒1.10].
Figure 1.1 – Block diagram of non-adaptive system
Forming of information about viewing conditions and about transformer characteristics
Viewing conditions at the shooting place
Transition to device independed and viewing conditions independent standard color space
Transition from standard color space to reproduction colour space