Description Usage Arguments Details Value Author(s) See Also Examples

The following functions perform all spatial linear transforms: reflection, rotation, translation, resizing, and general affine transform.

1 2 3 4 5 6 7 | ```
flip(x)
flop(x)
rotate(x, angle, filter = "bilinear", output.dim, output.origin, ...)
translate(x, v, filter = "none", ...)
resize(x, w, h, output.dim = c(w, h), output.origin = c(0, 0), antialias = FALSE, ...)
affine(x, m, filter = c("bilinear", "none"), output.dim, bg.col = "black", antialias = TRUE)
``` |

`x` |
An |

`angle` |
A numeric specifying the image rotation angle in degrees. |

`v` |
A vector of 2 numbers denoting the translation vector in pixels. |

`w, h` |
Width and height of the resized image. One of these arguments can be missing to enable proportional resizing. |

`filter` |
A character string indicating the interpolating sampling filter. Valid values are 'none' or 'bilinear'. See Details. |

`output.dim` |
A vector of 2 numbers indicating the dimension of the output image.
For |

`output.origin` |
A vector of 2 numbers indicating the output coordinates of the origin in pixels. |

`m` |
A 3x2 matrix describing the affine transformation. See Details. |

`bg.col` |
Color used to fill the background pixels, defaults to "black". In the case of multi-frame images the value is recycled, and individual background for each frame can be specified by providing a vector. |

`antialias` |
If |

`...` |
Arguments to be passed to |

`flip`

mirrors `x`

around the image horizontal axis (vertical reflection).

`flop`

mirrors `x`

around the image vertical axis (horizontal reflection).

`rotate`

rotates the image clockwise by the given angle around the
origin specified in `output.origin`

. If no `output.origin`

is
provided, the result will be centered in a recalculated bounding box unless
`output.dim`

is provided.

`resize`

scales the image `x`

to the desired dimensions.
The transformation origin can be specified in `output.origin`

.
For example, zooming about the `output.origin`

can be achieved by setting
`output.dim`

to a value different from `c(w, h)`

.

`affine`

returns the affine transformation of `x`

, where
pixels coordinates, denoted by the matrix `px`

, are
transformed to `cbind(px, 1)%*%m`

.

All spatial transformations except `flip`

and `flop`

are based on the
general `affine`

transformation. Spatial interpolation can be either
`none`

, also called nearest neighbor, where the resulting pixel value equals to
the closest pixel value, or `bilinear`

, where the new
pixel value is computed by bilinear approximation of the 4 neighboring pixels. The
`bilinear`

filter gives smoother results.

An `Image`

object or an array, containing the transformed version
of `x`

.

Gregoire Pau, 2012

1 2 3 4 5 6 7 8 9 10 11 |

```
```

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