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Add rotation module and functions #669

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merged 3 commits into from
Jun 13, 2024
Merged

Add rotation module and functions #669

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3dbb20a
add rotation module and functions
ripytide Jun 12, 2024
df27fa4
move rotate functions to the geometric_transformations module
ripytide Jun 12, 2024
0680fbd
fix doc-tests
ripytide Jun 12, 2024
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140 changes: 140 additions & 0 deletions src/geometric_transformations.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -317,6 +317,146 @@ where
warp(image, &projection, interpolation, default)
}

/// Rotates an image 90 degrees clockwise.
///
/// # Examples
/// ```
/// use imageproc::geometric_transformations::rotate90;
/// use imageproc::gray_image;
///
/// let image = gray_image!(
/// 1, 2, 0, 0;
/// 3, 4, 0, 0;
/// 0, 0, 0, 0;
/// 0, 0, 0, 0);
///
/// let rotated = rotate90(&image);
///
/// assert_eq!(rotated, gray_image!(
/// 0, 0, 3, 1;
/// 0, 0, 4, 2;
/// 0, 0, 0, 0;
/// 0, 0, 0, 0));
/// ```
pub fn rotate90<P>(image: &Image<P>) -> Image<P>
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I don’t feel strongly either way but it’s a bit unfortunate to use angles in degrees in the names of these functions when angles everywhere else in this file (/crate) are in radians. Can’t think of better names off the top of my head though.

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As some prior art, opencv just has a single rotate() function which takes an enum that looks like ROTATE_90_CLOCKWISE

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Maybe we should do the same and use a single function with an enum, but I don't feel particularly strongly either way.

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I wondered the same thing. I’ll just merge as is for now. Thanks.

where
P: Pixel,
{
let (width, height) = image.dimensions();

let mut rotated = Image::new(height, width);

for y in 0..height {
for x in 0..width {
rotated.put_pixel(height - y - 1, x, *image.get_pixel(x, y));
}
}

rotated
}

/// Rotates an image 270 degrees clockwise.
///
/// # Examples
/// ```
/// use imageproc::geometric_transformations::rotate270;
/// use imageproc::gray_image;
///
/// let image = gray_image!(
/// 1, 2, 0, 0;
/// 3, 4, 0, 0;
/// 0, 0, 0, 0;
/// 0, 0, 0, 0);
///
/// let rotated = rotate270(&image);
///
/// assert_eq!(rotated, gray_image!(
/// 0, 0, 0, 0;
/// 0, 0, 0, 0;
/// 2, 4, 0, 0;
/// 1, 3, 0, 0));
/// ```
pub fn rotate270<P>(image: &Image<P>) -> Image<P>
where
P: Pixel,
{
let (width, height) = image.dimensions();

let mut rotated = Image::new(height, width);

for y in 0..height {
for x in 0..width {
rotated.put_pixel(y, width - x - 1, *image.get_pixel(x, y));
}
}

rotated
}

/// Rotates an image 180 degrees clockwise.
///
/// # Examples
/// ```
/// use imageproc::geometric_transformations::rotate180;
/// use imageproc::gray_image;
///
/// let image = gray_image!(
/// 1, 2, 0, 0;
/// 3, 4, 0, 0;
/// 0, 0, 0, 0;
/// 0, 0, 0, 0);
///
/// let rotated = rotate180(&image);
///
/// assert_eq!(rotated, gray_image!(
/// 0, 0, 0, 0;
/// 0, 0, 0, 0;
/// 0, 0, 4, 3;
/// 0, 0, 2, 1));
/// ```
pub fn rotate180<P>(image: &Image<P>) -> Image<P>
where
P: Pixel,
{
let mut out = image.clone();
rotate180_mut(&mut out);
out
}
#[doc=generate_mut_doc_comment!("rotate180")]
pub fn rotate180_mut<P>(image: &mut Image<P>)
where
P: Pixel,
{
let (width, height) = image.dimensions();

for y in 0..height / 2 {
for x in 0..width {
let x180 = width - x - 1;
let y180 = height - y - 1;

let p = *image.get_pixel(x, y);
let p180 = *image.get_pixel(x180, y180);

image.put_pixel(x, y, p180);
image.put_pixel(x180, y180, p);
}
}

if height % 2 != 0 {
let y_middle = height / 2;

for x in 0..width / 2 {
let x180 = width - x - 1;

let p = *image.get_pixel(x, y_middle);
let p180 = *image.get_pixel(x180, y_middle);

image.put_pixel(x, y_middle, p180);
image.put_pixel(x180, y_middle, p);
}
}
}

/// Translates the input image by t. Note that image coordinates increase from
/// top left to bottom right. Output pixels whose pre-image are not in the input
/// image are set to the boundary pixel in the input image nearest to their pre-image.
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