Downsample or upsample chrominance components of images
H = vision.ChromaResampler returns a chroma resampling System object, H, that downsamples or upsamples chroma components of a YCbCr signal to reduce the bandwidth and storage requirements.
H = vision.ChromaResampler(Name,Value) returns a chroma resampling System object, H, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1, Value1,...,NameN,ValueN).
|Code Generation Support|
|Supports MATLAB® Function block: Yes|
|System Objects in MATLAB Code Generation|
|Code Generation Support, Usage Notes, and Limitations.|
To downsample the chrominance components of images, set this property to one of the following:
To upsample the chrominance components of images, set this property to one of the following:
The default is [4:4:4 to 4:2:2]
Method used to approximate missing values
Specify the interpolation method used to approximate the missing chrominance values as one of Pixel replication | Linear. The default is Linear. When you set this property to Linear, the object uses linear interpolation to calculate the missing values. When you set this property to Pixel replication, the object replicates the chrominance values of the neighboring pixels to create the upsampled image. This property applies when you upsample the chrominance values.
Lowpass filter used to prevent aliasing
Specify the lowpass filter used to prevent aliasing as one of Auto | Property | None. The default is Auto. When you set this property to Auto, the object uses a built-in lowpass filter. When you set this property to Property, the coefficients of the filters are specified by the HorizontalFilterCoefficients and VerticalFilterCoefficients properties. When you set this property to None, the object does not filter the input signal. This property applies when you downsample the chrominance values.
Horizontal filter coefficients
Specify the filter coefficients to apply to the input signal. This property applies when you set the Resampling property to one of [4:4:4 to 4:2:2] | [4:4:4 to 4:2:0 (MPEG1)] | [4:4:4 to 4:2:0 (MPEG2)] | [4:4:4 to 4:1:1] and the AntialiasingFilterSource property to Property. The default is [0.2 0.6 0.2].
Vertical filter coefficients
Specify the filter coefficients to apply to the input signal. This property applies when you set the Resampling property to one of [4:4:4 to 4:2:0 (MPEG1)] | [4:4:4 to 4:2:0 (MPEG2)] | [4:2:2 to 4:2:0 (MPEG1)] | [4:2:2 to 4:2:0 (MPEG2)] and the AntialiasingFilterSource property to Property. The default is [0.5 0.5].
Input is row-major format
Set this property to true when the input contains data elements from the first row first, then data elements from the second row second, and so on through the last row. Otherwise, the object assumes that the input data is stored in column-major format. The default is false.
|clone||Create chroma resampling object with same property values|
|getNumInputs||Number of expected inputs to step method|
|getNumOutputs||Number of outputs from step method|
|isLocked||Locked status for input attributes and nontunable properties|
|release||Allow property value and input characteristics changes|
|step||Resample input chrominance components|
Resample the chrominance components of an image.
H = vision.ChromaResampler; hcsc = vision.ColorSpaceConverter; x = imread('peppers.png'); x1 = step(hcsc, x); [Cb, Cr] = step(H, x1(:,:,2), x1(:,:,3));
This object implements the algorithm, inputs, and outputs described on the Chroma Resampling block reference page. The object properties correspond to the block parameters.