Annex E, Wheel Slot Image Definition
Wheel slot image definition
Annex E (normative) Wheel Slot Image Definition
Definition of images used in wheel slots to visualize gobos, animation wheels or color wheels.
Gobo images shall be in PNG format with an alpha channel. Indexed, Greyscale and Alpha, 8bit RGB and Alpha, or 16bit RGB and Alpha are accepted pixel formats.
A gobo image is comprised of a transparent Background (1) and the image itself on top. The Background shall be fully transparent and should be considered to be the equivalent of a gobo holder. The Image region shall be fully opaque aside from anti-aliasing, and shall be as large as possible.
Note 1: This allows a data consumer to determine the precise pixel extents of the Image and place the provided PNG over an arbitrary GUI background without additional processing.
The Background region, the equivalent of gobo holder, is defined by full transparency (Alpha 0). In the Image region, Pure Black (RGB 0,0,0) is opaque (2), and Pure White (RGB 255,255,255) is transparent (letter A).
Colored gobos (3) shall use an RGB approximation. The RGB approximation shall be calculated on the basis of Pure White being the CCT of the fixture light source and the ICC color profile embedded within the PNG. (See ISO 15076-1:2010) The default shall be sRGB.