Duotone Alpha

Applies an alpha mask to the duotone effect generated by the duotone parameter.

The duotone parameter accepts colors, expressed as either color keywords or 3- (RGB) or 6-digit (RRGGBB) hexadecimal color values. The opacity of the duotone effect can also be set separately using the parameter duotone-alpha. The default value is 100, which makes the duotone fully opaque. To blend the duotone with the original image, set a lower duotone-alpha value.