Attributes for a filter and its parameters.
- Core Image
Attribute keys are used for the attribute dictionary of a filter. Most entries in the attribute dictionary are optional. The attribute
k is mandatory. For a parameter, the attribute
k is mandatory because it specifies the class name of the filter.
A parameter of type
NSNumber does not necessarily need the attributes
k. These attributes are not present when the parameter has no upper or lower bounds. For example, the Gaussian blur filter has a radius parameter with a minimum of
0 but no maximum value to indicate that all nonnegative values are valid.