rgb2gray — Convert RGB image data to grayscale intensity values using MATLAB-compatible luminance weighting.
rgb2gray(RGB) converts an MxNx3 truecolor image to grayscale with standard luminance weighting. Output typing and scaling follow MATLAB-compatible image-conversion rules for integer and floating-point inputs.
Syntax
I = rgb2gray(RGB)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
RGB | Any | Yes | — | RGB truecolor image or double colormap. |
Returns
| Name | Type | Description |
|---|---|---|
I | NumericArray | Grayscale image converted from RGB input. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:rgb2gray:TooManyInputs | More than one input argument is supplied. | rgb2gray: too many input arguments |
RunMat:rgb2gray:InvalidInput | Input cannot be interpreted as an MxNx3 RGB image or an Nx3 double colormap. | rgb2gray: invalid input |
RunMat:rgb2gray:Internal | Grayscale output tensor construction fails internally. | rgb2gray: internal conversion failure |
How rgb2gray works
- Accepts MxNx3 truecolor images.
- Uses weights 0.2989, 0.5870, and 0.1140 for red, green, and blue.
- Preserves native uint8, uint16, single, and double output storage. Integer conversion uses nearest rounding with ties away from zero and saturation; unsupported signed, uint32, and uint64 image classes reject before resident download.
Example
Convert RGB To Gray
I = rgb2gray(RGB);Expected output:
% I is MxNUsing rgb2gray with coding agents
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Related Image functions
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how rgb2gray is executed, line by line, in Rust.
- View the source for rgb2gray in Rust on GitHub
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- Found a bug? Open an issue with a minimal reproduction.
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