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Fixed-Point Support for MATLAB System Objects

Getting Information About Fixed-Point System Objects

System objects that support fixed-point data processing have fixed-point properties. When you display the properties of a System object™, click Show all properties at the end of the property list to display the fixed-point properties for that object. You can also display the fixed-point properties for a particular object by typing vision.<ObjectName>.helpFixedPoint at the command line.

The following Computer Vision Toolbox™ objects support fixed-point data processing.

 Fixed-Point Data Processing Support

Setting System Object Fixed-Point Properties

Several properties affect the fixed-point data processing used by a System object. Objects perform fixed-point processing and use the current fixed-point property settings when they receive fixed-point input.

You change the values of fixed-point properties in the same way as you change any System object property value. You also use the Fixed-Point Designer™ numerictype (Fixed-Point Designer) object to specify the desired data type as fixed point, the signedness, and the word- and fraction-lengths.

In the same way as for blocks, the data type properties of many System objects can set the appropriate word lengths and scalings automatically by using full precision. System objects assume that the target specified on the Configuration Parameters Hardware Implementation target is ASIC/FPGA.

If you have not set the property that activates a dependent property and you attempt to change that dependent property, you will get a warning message.

You must set the property that activates a dependent property before attempting to change the dependent property. If you do not set the activating property, you will get a warning message.


System objects do not support fixed-point word lengths greater than 128 bits.

For any System object provided in the Toolbox, the fimath settings for any fimath attached to a fi input or a fi property are ignored. Outputs from a System object never have an attached fimath.