# nvidia.dali.fn.warp_affine¶

nvidia.dali.fn.warp_affine(*inputs, **kwargs)

Applies an affine transformation to the images.

This operator supports volumetric data.

Supported backends
• ‘cpu’

• ‘gpu’

Parameters
• input0 (TensorList ('HWC', 'FHWC', 'DHWC', 'FDHWC')) – Input to the operator.

• input1 (TensorList, optional) – Input to the operator.

Keyword Arguments
• bytes_per_sample_hint (int or list of int, optional, default = [0]) –

Output size hint, in bytes per sample.

If specified, the operator’s outputs residing in GPU or page-locked host memory will be preallocated to accommodate a batch of samples of this size.

• dtype (nvidia.dali.types.DALIDataType, optional) –

Output data type.

If not set, the input type is used.

• fill_value (float, optional) –

Value used to fill areas that are outside the source image.

If a value is not specified, the source coordinates are clamped and the border pixel is repeated.

• interp_type (nvidia.dali.types.DALIInterpType, optional, default = DALIInterpType.INTERP_LINEAR) – Type of interpolation used.

• inverse_map (bool, optional, default = True) – Set to False if the given transform is a destination to source mapping, True otherwise.

• matrix (float or list of float or TensorList of float, optional, default = []) –

Transform matrix.

When the inverse_map option is set to true (default), the matrix represents a destination to source mapping. With a list of values (M11, M12, M13, M21, M22, M23), this operation produces a new image by using the following formula:

dst(x,y) = src(M11 * x + M12 * y + M13, M21 * x + M22 * y + M23)


Where [0, 0] coordinate means the corner of the first pixel.

If the inverse_map option is set to false, the matrix represents a source to destination transform and it is inverted before applying the formula above.

It is equivalent to OpenCV’s warpAffine operation with the inverse_map argument being analog to the WARP_INVERSE_MAP flag.

Supports per-frame inputs.

• preserve (bool, optional, default = False) – Prevents the operator from being removed from the graph even if its outputs are not used.

• seed (int, optional, default = -1) –

Random seed.

If not provided, it will be populated based on the global seed of the pipeline.

• size (float or list of float or TensorList of float, optional, default = []) –

Output size, in pixels/points.

Non-integer sizes are rounded to nearest integer. The channel dimension should be excluded (for example, for RGB images, specify (480,640), not (480,640,3).

• output_dtype (nvidia.dali.types.DALIDataType) –

Warning

The argument output_dtype is a deprecated alias for dtype. Use dtype instead.