2-D FIR Filter

2-D FIR filter on input matrix

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Libraries:
Computer Vision Toolbox / Filtering

Description

The 2-D FIR Filter block filters a 2-D grayscale image using a 2-D finite impulse response (FIR) filter represented as a 2-D coefficient matrix or a pair of separable filter coefficient vectors.

Examples

Filter Image Using FIR Filter

Filter an image using an FIR filter.

• Open Live Script

Ports

Input

I — Input image

matrix

Input image, specified as a numeric matrix.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Complex Number Support: Yes

H — Filter coefficients

matrix

Filter coefficients, specified as a numeric matrix. The input to the H port must have the same data type as the input to the I port.

Dependencies

To enable this port, set the Coefficient source parameter to Input port.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Complex Number Support: Yes

HV — Vertical filter coefficients

vector

Vertical filter coefficients, specified as a numeric vector. The input to the HV port must have the same data type as the input to the I port.

Dependencies

To enable this port, specify these parameter values.

• Separable filter coefficients — on

• Coefficient source — Input port

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Complex Number Support: Yes

HH — Horizontal filter coefficients

vector

Horizontal filter coefficients, specified as a numeric vector. The input to the HH port must have the same data type as the input to the I port.

Dependencies

To enable this port, specify these parameter values.

• Separable filter coefficients — on

• Coefficient source — Input port

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Complex Number Support: Yes

PVal — Pad value

scalar

Pad value, specified as a numeric scalar. The input to the PVal port must have the same data type as the input to the I port.

Dependencies

To enable this port, specify these parameter values.

• Output size — Full or Same as input port I

• Padding options — Constant

• Pad value source — Input port

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Complex Number Support: Yes

Output

Output — Filtered output image

matrix

Filtered output image, returned as a numeric matrix of the same data type as the input image.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point

Parameters

Main

Separable filter coefficients — Filter coefficients are separable

off (default) | on

Select this parameter if your filter coefficients are separable. Using separable filter coefficients reduces the number of calculations the block must perform to compute the output. You can use isfilterseparable to check if your filter is separable and compute the vertical and horizontal filter coefficients.

Coefficient source — Source of filter coefficients

Specify via dialog (default) | Input port

Specify the source of the filter coefficients as one of these options.

• Specify via dialog — Specify the filter coefficients using the Coefficients parameter or, if you select the Separable filter coefficients parameter, by using the Vertical coefficients (across height) and Horizontal coefficients (across width) parameters.

• Input port — Specify the filter coefficients using the H port, or if you select the Separable filter coefficients parameter, by using the HV and HH ports.

Coefficients — Filter coefficients

[1 0; 0 -1] (default) | numeric matrix

Specify the filter coefficients as a numeric matrix.

Dependencies

To enable this parameter, specify these parameter values.

• Separable filter coefficients — off

• Coefficient source — Specify via dialog

Vertical coefficients (across height) — Vertical filter coefficients

[4 0] (default) | numeric vector

Specify the vertical filter coefficients as a numeric vector.

Dependencies

To enable this parameter, specify these parameter values.

• Separable filter coefficients — on

• Coefficient source — Specify via dialog

Horizontal coefficients (across height) — Horizontal filter coefficients

[4 0] (default) | numeric vector

Specify the horizontal filter coefficients as a numeric vector.

Dependencies

To enable this parameter, specify these parameter values.

• Separable filter coefficients — on

• Coefficient source — Specify via dialog

Output size — Size of filtered image

Full (default) | Same as input port I | Valid

For an input image having dimensions M-by-N and a filter having dimensions P-by-Q, specify the size of the filtered image as one of these options.

• Full — The block uses padding to return a filtered image with full dimensions (M+P–1)-by-(N+Q–1).

• Same as input port I — The block uses padding to return a filtered image with dimensions M-by-N, the same size as the input image.

• Valid — The block filters the input image only where the coefficient matrix fits entirely within it without padding, and returns a filtered image with dimensions (M–P+1)-by-(N–Q+1).

Padding options — Padding method

Constant (default) | Replicate | Symmetric | Circular

Specify the padding method as one of these options.

• Constant — Pads the input image with a constant value.

• Replicate — Pads the input image by repeating its border values.

• Symmetric — Pads the input image by mirror-reflecting the image across its border.

• Circular — Pads the input image by assuming the image is periodic.

Dependencies

To enable this parameter, specify the Output size parameter as either Full or Same as input port I.

Pad value source — Source of padding value

Specify via dialog (default) | Input port

Specify the source of the padding value as one of these options.

• Specify via dialog — Specify the pad value using the Pad value parameter.

• Input port — Specify the pad value using the PVal port.

Dependencies

To enable this parameter, specify these parameter values.

• Output size — Full or Same as input port I

• Padding options — Constant

Pad value — Padding value

0 (default) | numeric scalar

Specify the padding value as a numeric scalar.

Dependencies

To enable this parameter, specify these parameter values.

• Output size — Full or Same as input port I

• Padding options — Constant

• Pad value source — Specify via dialog

Filtering based on — Method of filtering

Convolution (default) | Correlation

Specify the method of filtering as Convolution or Correlation.

Data Types

For details on the fixed-point block parameters, see Specify Fixed-Point Attributes for Blocks (DSP System Toolbox).

Lock data type settings against change by the fixed-point tools — Prevent fixed-point tools from overriding data types

off (default) | on

Select this parameter to prevent the fixed-point tools from overriding the data types you specify in this block. For more information, see Lock the Output Data Type Setting (Fixed-Point Designer).

Block Characteristics

Data Types	double | fixed point | integer | single
Multidimensional Signals	no
Variable-Size Signals	yes

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a