* {{Parameter|rgbaColorIndex&}} is the ''RGBA'' color value or palette index of the color to retrieve the blue component intensity from.
* The [[LONG]] intensity value returned ranges from 0 (no intensity, not present) to 255 (full intensity).
* If {{Parameter|imageHandle&}} specifies a 32-bit color image, {{Parameter|rgbaColorIndex&}} is interpreted as a 32-bit ''RGBA'' color value.
* If {{Parameter|imageHandle&}} specifies an image that uses a palette, {{Parameter|rgbaColorIndex&}} is interpreted as a palette index.
* If {{Parameter|imageHandle&}} is not specified, it is assumed to be the current write page.
* If {{Parameter|imageHandle&}} is an invalid handle, an [[ERROR Codes|invalid handle]] error will occur.
* If {{Parameter|rgbaColorIndex&}} is outside the range of valid indexes for a given image mode, an [[ERROR Codes|illegal function call]] error occurs.