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authorValentin Popov <valentin@popov.link>2024-07-19 15:37:58 +0300
committerValentin Popov <valentin@popov.link>2024-07-19 15:37:58 +0300
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tree15afc392522a9e85dc3332235e311b7d39352ea9 /vendor/image/src/imageops/sample.rs
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-//! Functions and filters for the sampling of pixels.
-
-// See http://cs.brown.edu/courses/cs123/lectures/08_Image_Processing_IV.pdf
-// for some of the theory behind image scaling and convolution
-
-use std::f32;
-
-use num_traits::{NumCast, ToPrimitive, Zero};
-
-use crate::image::{GenericImage, GenericImageView};
-use crate::traits::{Enlargeable, Pixel, Primitive};
-use crate::utils::clamp;
-use crate::{ImageBuffer, Rgba32FImage};
-
-/// Available Sampling Filters.
-///
-/// ## Examples
-///
-/// To test the different sampling filters on a real example, you can find two
-/// examples called
-/// [`scaledown`](https://github.com/image-rs/image/tree/master/examples/scaledown)
-/// and
-/// [`scaleup`](https://github.com/image-rs/image/tree/master/examples/scaleup)
-/// in the `examples` directory of the crate source code.
-///
-/// Here is a 3.58 MiB
-/// [test image](https://github.com/image-rs/image/blob/master/examples/scaledown/test.jpg)
-/// that has been scaled down to 300x225 px:
-///
-/// <!-- NOTE: To test new test images locally, replace the GitHub path with `../../../docs/` -->
-/// <div style="display: flex; flex-wrap: wrap; align-items: flex-start;">
-/// <div style="margin: 0 8px 8px 0;">
-/// <img src="https://raw.githubusercontent.com/image-rs/image/master/examples/scaledown/scaledown-test-near.png" title="Nearest"><br>
-/// Nearest Neighbor
-/// </div>
-/// <div style="margin: 0 8px 8px 0;">
-/// <img src="https://raw.githubusercontent.com/image-rs/image/master/examples/scaledown/scaledown-test-tri.png" title="Triangle"><br>
-/// Linear: Triangle
-/// </div>
-/// <div style="margin: 0 8px 8px 0;">
-/// <img src="https://raw.githubusercontent.com/image-rs/image/master/examples/scaledown/scaledown-test-cmr.png" title="CatmullRom"><br>
-/// Cubic: Catmull-Rom
-/// </div>
-/// <div style="margin: 0 8px 8px 0;">
-/// <img src="https://raw.githubusercontent.com/image-rs/image/master/examples/scaledown/scaledown-test-gauss.png" title="Gaussian"><br>
-/// Gaussian
-/// </div>
-/// <div style="margin: 0 8px 8px 0;">
-/// <img src="https://raw.githubusercontent.com/image-rs/image/master/examples/scaledown/scaledown-test-lcz2.png" title="Lanczos3"><br>
-/// Lanczos with window 3
-/// </div>
-/// </div>
-///
-/// ## Speed
-///
-/// Time required to create each of the examples above, tested on an Intel
-/// i7-4770 CPU with Rust 1.37 in release mode:
-///
-/// <table style="width: auto;">
-/// <tr>
-/// <th>Nearest</th>
-/// <td>31 ms</td>
-/// </tr>
-/// <tr>
-/// <th>Triangle</th>
-/// <td>414 ms</td>
-/// </tr>
-/// <tr>
-/// <th>CatmullRom</th>
-/// <td>817 ms</td>
-/// </tr>
-/// <tr>
-/// <th>Gaussian</th>
-/// <td>1180 ms</td>
-/// </tr>
-/// <tr>
-/// <th>Lanczos3</th>
-/// <td>1170 ms</td>
-/// </tr>
-/// </table>
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub enum FilterType {
- /// Nearest Neighbor
- Nearest,
-
- /// Linear Filter
- Triangle,
-
- /// Cubic Filter
- CatmullRom,
-
- /// Gaussian Filter
- Gaussian,
-
- /// Lanczos with window 3
- Lanczos3,
-}
-
-/// A Representation of a separable filter.
-pub(crate) struct Filter<'a> {
- /// The filter's filter function.
- pub(crate) kernel: Box<dyn Fn(f32) -> f32 + 'a>,
-
- /// The window on which this filter operates.
- pub(crate) support: f32,
-}
-
-struct FloatNearest(f32);
-
-// to_i64, to_u64, and to_f64 implicitly affect all other lower conversions.
-// Note that to_f64 by default calls to_i64 and thus needs to be overridden.
-impl ToPrimitive for FloatNearest {
- // to_{i,u}64 is required, to_{i,u}{8,16} are useful.
- // If a usecase for full 32 bits is found its trivial to add
- fn to_i8(&self) -> Option<i8> {
- self.0.round().to_i8()
- }
- fn to_i16(&self) -> Option<i16> {
- self.0.round().to_i16()
- }
- fn to_i64(&self) -> Option<i64> {
- self.0.round().to_i64()
- }
- fn to_u8(&self) -> Option<u8> {
- self.0.round().to_u8()
- }
- fn to_u16(&self) -> Option<u16> {
- self.0.round().to_u16()
- }
- fn to_u64(&self) -> Option<u64> {
- self.0.round().to_u64()
- }
- fn to_f64(&self) -> Option<f64> {
- self.0.to_f64()
- }
-}
-
-// sinc function: the ideal sampling filter.
-fn sinc(t: f32) -> f32 {
- let a = t * f32::consts::PI;
-
- if t == 0.0 {
- 1.0
- } else {
- a.sin() / a
- }
-}
-
-// lanczos kernel function. A windowed sinc function.
-fn lanczos(x: f32, t: f32) -> f32 {
- if x.abs() < t {
- sinc(x) * sinc(x / t)
- } else {
- 0.0
- }
-}
-
-// Calculate a splice based on the b and c parameters.
-// from authors Mitchell and Netravali.
-fn bc_cubic_spline(x: f32, b: f32, c: f32) -> f32 {
- let a = x.abs();
-
- let k = if a < 1.0 {
- (12.0 - 9.0 * b - 6.0 * c) * a.powi(3)
- + (-18.0 + 12.0 * b + 6.0 * c) * a.powi(2)
- + (6.0 - 2.0 * b)
- } else if a < 2.0 {
- (-b - 6.0 * c) * a.powi(3)
- + (6.0 * b + 30.0 * c) * a.powi(2)
- + (-12.0 * b - 48.0 * c) * a
- + (8.0 * b + 24.0 * c)
- } else {
- 0.0
- };
-
- k / 6.0
-}
-
-/// The Gaussian Function.
-/// ```r``` is the standard deviation.
-pub(crate) fn gaussian(x: f32, r: f32) -> f32 {
- ((2.0 * f32::consts::PI).sqrt() * r).recip() * (-x.powi(2) / (2.0 * r.powi(2))).exp()
-}
-
-/// Calculate the lanczos kernel with a window of 3
-pub(crate) fn lanczos3_kernel(x: f32) -> f32 {
- lanczos(x, 3.0)
-}
-
-/// Calculate the gaussian function with a
-/// standard deviation of 0.5
-pub(crate) fn gaussian_kernel(x: f32) -> f32 {
- gaussian(x, 0.5)
-}
-
-/// Calculate the Catmull-Rom cubic spline.
-/// Also known as a form of `BiCubic` sampling in two dimensions.
-pub(crate) fn catmullrom_kernel(x: f32) -> f32 {
- bc_cubic_spline(x, 0.0, 0.5)
-}
-
-/// Calculate the triangle function.
-/// Also known as `BiLinear` sampling in two dimensions.
-pub(crate) fn triangle_kernel(x: f32) -> f32 {
- if x.abs() < 1.0 {
- 1.0 - x.abs()
- } else {
- 0.0
- }
-}
-
-/// Calculate the box kernel.
-/// Only pixels inside the box should be considered, and those
-/// contribute equally. So this method simply returns 1.
-pub(crate) fn box_kernel(_x: f32) -> f32 {
- 1.0
-}
-
-// Sample the rows of the supplied image using the provided filter.
-// The height of the image remains unchanged.
-// ```new_width``` is the desired width of the new image
-// ```filter``` is the filter to use for sampling.
-// ```image``` is not necessarily Rgba and the order of channels is passed through.
-fn horizontal_sample<P, S>(
- image: &Rgba32FImage,
- new_width: u32,
- filter: &mut Filter,
-) -> ImageBuffer<P, Vec<S>>
-where
- P: Pixel<Subpixel = S> + 'static,
- S: Primitive + 'static,
-{
- let (width, height) = image.dimensions();
- let mut out = ImageBuffer::new(new_width, height);
- let mut ws = Vec::new();
-
- let max: f32 = NumCast::from(S::DEFAULT_MAX_VALUE).unwrap();
- let min: f32 = NumCast::from(S::DEFAULT_MIN_VALUE).unwrap();
- let ratio = width as f32 / new_width as f32;
- let sratio = if ratio < 1.0 { 1.0 } else { ratio };
- let src_support = filter.support * sratio;
-
- for outx in 0..new_width {
- // Find the point in the input image corresponding to the centre
- // of the current pixel in the output image.
- let inputx = (outx as f32 + 0.5) * ratio;
-
- // Left and right are slice bounds for the input pixels relevant
- // to the output pixel we are calculating. Pixel x is relevant
- // if and only if (x >= left) && (x < right).
-
- // Invariant: 0 <= left < right <= width
-
- let left = (inputx - src_support).floor() as i64;
- let left = clamp(left, 0, <i64 as From<_>>::from(width) - 1) as u32;
-
- let right = (inputx + src_support).ceil() as i64;
- let right = clamp(
- right,
- <i64 as From<_>>::from(left) + 1,
- <i64 as From<_>>::from(width),
- ) as u32;
-
- // Go back to left boundary of pixel, to properly compare with i
- // below, as the kernel treats the centre of a pixel as 0.
- let inputx = inputx - 0.5;
-
- ws.clear();
- let mut sum = 0.0;
- for i in left..right {
- let w = (filter.kernel)((i as f32 - inputx) / sratio);
- ws.push(w);
- sum += w;
- }
- ws.iter_mut().for_each(|w| *w /= sum);
-
- for y in 0..height {
- let mut t = (0.0, 0.0, 0.0, 0.0);
-
- for (i, w) in ws.iter().enumerate() {
- let p = image.get_pixel(left + i as u32, y);
-
- #[allow(deprecated)]
- let vec = p.channels4();
-
- t.0 += vec.0 * w;
- t.1 += vec.1 * w;
- t.2 += vec.2 * w;
- t.3 += vec.3 * w;
- }
-
- #[allow(deprecated)]
- let t = Pixel::from_channels(
- NumCast::from(FloatNearest(clamp(t.0, min, max))).unwrap(),
- NumCast::from(FloatNearest(clamp(t.1, min, max))).unwrap(),
- NumCast::from(FloatNearest(clamp(t.2, min, max))).unwrap(),
- NumCast::from(FloatNearest(clamp(t.3, min, max))).unwrap(),
- );
-
- out.put_pixel(outx, y, t);
- }
- }
-
- out
-}
-
-/// Linearly sample from an image using coordinates in [0, 1].
-pub fn sample_bilinear<P: Pixel>(
- img: &impl GenericImageView<Pixel = P>,
- u: f32,
- v: f32,
-) -> Option<P> {
- if ![u, v].iter().all(|c| (0.0..=1.0).contains(c)) {
- return None;
- }
-
- let (w, h) = img.dimensions();
- if w == 0 || h == 0 {
- return None;
- }
-
- let ui = w as f32 * u - 0.5;
- let vi = h as f32 * v - 0.5;
- interpolate_bilinear(
- img,
- ui.max(0.).min((w - 1) as f32),
- vi.max(0.).min((h - 1) as f32),
- )
-}
-
-/// Sample from an image using coordinates in [0, 1], taking the nearest coordinate.
-pub fn sample_nearest<P: Pixel>(
- img: &impl GenericImageView<Pixel = P>,
- u: f32,
- v: f32,
-) -> Option<P> {
- if ![u, v].iter().all(|c| (0.0..=1.0).contains(c)) {
- return None;
- }
-
- let (w, h) = img.dimensions();
- let ui = w as f32 * u - 0.5;
- let ui = ui.max(0.).min((w.saturating_sub(1)) as f32);
-
- let vi = h as f32 * v - 0.5;
- let vi = vi.max(0.).min((h.saturating_sub(1)) as f32);
- interpolate_nearest(img, ui, vi)
-}
-
-/// Sample from an image using coordinates in [0, w-1] and [0, h-1], taking the
-/// nearest pixel.
-///
-/// Coordinates outside the image bounds will return `None`, however the
-/// behavior for points within half a pixel of the image bounds may change in
-/// the future.
-pub fn interpolate_nearest<P: Pixel>(
- img: &impl GenericImageView<Pixel = P>,
- x: f32,
- y: f32,
-) -> Option<P> {
- let (w, h) = img.dimensions();
- if w == 0 || h == 0 {
- return None;
- }
- if !(0.0..=((w - 1) as f32)).contains(&x) {
- return None;
- }
- if !(0.0..=((h - 1) as f32)).contains(&y) {
- return None;
- }
-
- Some(img.get_pixel(x.round() as u32, y.round() as u32))
-}
-
-/// Linearly sample from an image using coordinates in [0, w-1] and [0, h-1].
-pub fn interpolate_bilinear<P: Pixel>(
- img: &impl GenericImageView<Pixel = P>,
- x: f32,
- y: f32,
-) -> Option<P> {
- let (w, h) = img.dimensions();
- if w == 0 || h == 0 {
- return None;
- }
- if !(0.0..=((w - 1) as f32)).contains(&x) {
- return None;
- }
- if !(0.0..=((h - 1) as f32)).contains(&y) {
- return None;
- }
-
- let uf = x.floor();
- let vf = y.floor();
- let uc = (x + 1.).min((w - 1) as f32);
- let vc = (y + 1.).min((h - 1) as f32);
-
- // clamp coords to the range of the image
- let coords = [[uf, vf], [uf, vc], [uc, vf], [uc, vc]];
-
- assert!(coords
- .iter()
- .all(|&[u, v]| { img.in_bounds(u as u32, v as u32) }));
- let samples = coords.map(|[u, v]| img.get_pixel(u as u32, v as u32));
- assert!(P::CHANNEL_COUNT <= 4);
-
- // convert samples to f32
- // currently rgba is the largest one,
- // so just store as many items as necessary,
- // because there's not a simple way to be generic over all of them.
- let [sff, sfc, scf, scc] = samples.map(|s| {
- let mut out = [0.; 4];
- for (i, c) in s.channels().iter().enumerate() {
- out[i] = c.to_f32().unwrap();
- }
- out
- });
- // weights
- let [ufw, vfw] = [x - uf, y - vf];
- let [ucw, vcw] = [1. - ufw, 1. - vfw];
-
- // https://en.wikipedia.org/wiki/Bilinear_interpolation#Weighted_mean
- // the distance between pixels is 1 so there is no denominator
- let wff = ucw * vcw;
- let wfc = ucw * vfw;
- let wcf = ufw * vcw;
- let wcc = ufw * vfw;
- assert!(f32::abs((wff + wfc + wcf + wcc) - 1.) < 1e-3);
-
- // hack to get around not being able to construct a generic Pixel
- let mut out = samples[0];
- for (i, c) in out.channels_mut().iter_mut().enumerate() {
- let v = wff * sff[i] + wfc * sfc[i] + wcf * scf[i] + wcc * scc[i];
- // this rounding may introduce quantization errors,
- // but cannot do anything about it.
- *c = <P::Subpixel as NumCast>::from(v.round()).unwrap_or({
- if v < 0.0 {
- P::Subpixel::DEFAULT_MIN_VALUE
- } else {
- P::Subpixel::DEFAULT_MAX_VALUE
- }
- })
- }
- Some(out)
-}
-
-// Sample the columns of the supplied image using the provided filter.
-// The width of the image remains unchanged.
-// ```new_height``` is the desired height of the new image
-// ```filter``` is the filter to use for sampling.
-// The return value is not necessarily Rgba, the underlying order of channels in ```image``` is
-// preserved.
-fn vertical_sample<I, P, S>(image: &I, new_height: u32, filter: &mut Filter) -> Rgba32FImage
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S> + 'static,
- S: Primitive + 'static,
-{
- let (width, height) = image.dimensions();
- let mut out = ImageBuffer::new(width, new_height);
- let mut ws = Vec::new();
-
- let ratio = height as f32 / new_height as f32;
- let sratio = if ratio < 1.0 { 1.0 } else { ratio };
- let src_support = filter.support * sratio;
-
- for outy in 0..new_height {
- // For an explanation of this algorithm, see the comments
- // in horizontal_sample.
- let inputy = (outy as f32 + 0.5) * ratio;
-
- let left = (inputy - src_support).floor() as i64;
- let left = clamp(left, 0, <i64 as From<_>>::from(height) - 1) as u32;
-
- let right = (inputy + src_support).ceil() as i64;
- let right = clamp(
- right,
- <i64 as From<_>>::from(left) + 1,
- <i64 as From<_>>::from(height),
- ) as u32;
-
- let inputy = inputy - 0.5;
-
- ws.clear();
- let mut sum = 0.0;
- for i in left..right {
- let w = (filter.kernel)((i as f32 - inputy) / sratio);
- ws.push(w);
- sum += w;
- }
- ws.iter_mut().for_each(|w| *w /= sum);
-
- for x in 0..width {
- let mut t = (0.0, 0.0, 0.0, 0.0);
-
- for (i, w) in ws.iter().enumerate() {
- let p = image.get_pixel(x, left + i as u32);
-
- #[allow(deprecated)]
- let (k1, k2, k3, k4) = p.channels4();
- let vec: (f32, f32, f32, f32) = (
- NumCast::from(k1).unwrap(),
- NumCast::from(k2).unwrap(),
- NumCast::from(k3).unwrap(),
- NumCast::from(k4).unwrap(),
- );
-
- t.0 += vec.0 * w;
- t.1 += vec.1 * w;
- t.2 += vec.2 * w;
- t.3 += vec.3 * w;
- }
-
- #[allow(deprecated)]
- // This is not necessarily Rgba.
- let t = Pixel::from_channels(t.0, t.1, t.2, t.3);
-
- out.put_pixel(x, outy, t);
- }
- }
-
- out
-}
-
-/// Local struct for keeping track of pixel sums for fast thumbnail averaging
-struct ThumbnailSum<S: Primitive + Enlargeable>(S::Larger, S::Larger, S::Larger, S::Larger);
-
-impl<S: Primitive + Enlargeable> ThumbnailSum<S> {
- fn zeroed() -> Self {
- ThumbnailSum(
- S::Larger::zero(),
- S::Larger::zero(),
- S::Larger::zero(),
- S::Larger::zero(),
- )
- }
-
- fn sample_val(val: S) -> S::Larger {
- <S::Larger as NumCast>::from(val).unwrap()
- }
-
- fn add_pixel<P: Pixel<Subpixel = S>>(&mut self, pixel: P) {
- #[allow(deprecated)]
- let pixel = pixel.channels4();
- self.0 += Self::sample_val(pixel.0);
- self.1 += Self::sample_val(pixel.1);
- self.2 += Self::sample_val(pixel.2);
- self.3 += Self::sample_val(pixel.3);
- }
-}
-
-/// Resize the supplied image to the specific dimensions.
-///
-/// For downscaling, this method uses a fast integer algorithm where each source pixel contributes
-/// to exactly one target pixel. May give aliasing artifacts if new size is close to old size.
-///
-/// In case the current width is smaller than the new width or similar for the height, another
-/// strategy is used instead. For each pixel in the output, a rectangular region of the input is
-/// determined, just as previously. But when no input pixel is part of this region, the nearest
-/// pixels are interpolated instead.
-///
-/// For speed reasons, all interpolation is performed linearly over the colour values. It will not
-/// take the pixel colour spaces into account.
-pub fn thumbnail<I, P, S>(image: &I, new_width: u32, new_height: u32) -> ImageBuffer<P, Vec<S>>
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S> + 'static,
- S: Primitive + Enlargeable + 'static,
-{
- let (width, height) = image.dimensions();
- let mut out = ImageBuffer::new(new_width, new_height);
-
- let x_ratio = width as f32 / new_width as f32;
- let y_ratio = height as f32 / new_height as f32;
-
- for outy in 0..new_height {
- let bottomf = outy as f32 * y_ratio;
- let topf = bottomf + y_ratio;
-
- let bottom = clamp(bottomf.ceil() as u32, 0, height - 1);
- let top = clamp(topf.ceil() as u32, bottom, height);
-
- for outx in 0..new_width {
- let leftf = outx as f32 * x_ratio;
- let rightf = leftf + x_ratio;
-
- let left = clamp(leftf.ceil() as u32, 0, width - 1);
- let right = clamp(rightf.ceil() as u32, left, width);
-
- let avg = if bottom != top && left != right {
- thumbnail_sample_block(image, left, right, bottom, top)
- } else if bottom != top {
- // && left == right
- // In the first column we have left == 0 and right > ceil(y_scale) > 0 so this
- // assertion can never trigger.
- debug_assert!(
- left > 0 && right > 0,
- "First output column must have corresponding pixels"
- );
-
- let fraction_horizontal = (leftf.fract() + rightf.fract()) / 2.;
- thumbnail_sample_fraction_horizontal(
- image,
- right - 1,
- fraction_horizontal,
- bottom,
- top,
- )
- } else if left != right {
- // && bottom == top
- // In the first line we have bottom == 0 and top > ceil(x_scale) > 0 so this
- // assertion can never trigger.
- debug_assert!(
- bottom > 0 && top > 0,
- "First output row must have corresponding pixels"
- );
-
- let fraction_vertical = (topf.fract() + bottomf.fract()) / 2.;
- thumbnail_sample_fraction_vertical(image, left, right, top - 1, fraction_vertical)
- } else {
- // bottom == top && left == right
- let fraction_horizontal = (topf.fract() + bottomf.fract()) / 2.;
- let fraction_vertical = (leftf.fract() + rightf.fract()) / 2.;
-
- thumbnail_sample_fraction_both(
- image,
- right - 1,
- fraction_horizontal,
- top - 1,
- fraction_vertical,
- )
- };
-
- #[allow(deprecated)]
- let pixel = Pixel::from_channels(avg.0, avg.1, avg.2, avg.3);
- out.put_pixel(outx, outy, pixel);
- }
- }
-
- out
-}
-
-/// Get a pixel for a thumbnail where the input window encloses at least a full pixel.
-fn thumbnail_sample_block<I, P, S>(
- image: &I,
- left: u32,
- right: u32,
- bottom: u32,
- top: u32,
-) -> (S, S, S, S)
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S>,
- S: Primitive + Enlargeable,
-{
- let mut sum = ThumbnailSum::zeroed();
-
- for y in bottom..top {
- for x in left..right {
- let k = image.get_pixel(x, y);
- sum.add_pixel(k);
- }
- }
-
- let n = <S::Larger as NumCast>::from((right - left) * (top - bottom)).unwrap();
- let round = <S::Larger as NumCast>::from(n / NumCast::from(2).unwrap()).unwrap();
- (
- S::clamp_from((sum.0 + round) / n),
- S::clamp_from((sum.1 + round) / n),
- S::clamp_from((sum.2 + round) / n),
- S::clamp_from((sum.3 + round) / n),
- )
-}
-
-/// Get a thumbnail pixel where the input window encloses at least a vertical pixel.
-fn thumbnail_sample_fraction_horizontal<I, P, S>(
- image: &I,
- left: u32,
- fraction_horizontal: f32,
- bottom: u32,
- top: u32,
-) -> (S, S, S, S)
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S>,
- S: Primitive + Enlargeable,
-{
- let fract = fraction_horizontal;
-
- let mut sum_left = ThumbnailSum::zeroed();
- let mut sum_right = ThumbnailSum::zeroed();
- for x in bottom..top {
- let k_left = image.get_pixel(left, x);
- sum_left.add_pixel(k_left);
-
- let k_right = image.get_pixel(left + 1, x);
- sum_right.add_pixel(k_right);
- }
-
- // Now we approximate: left/n*(1-fract) + right/n*fract
- let fact_right = fract / ((top - bottom) as f32);
- let fact_left = (1. - fract) / ((top - bottom) as f32);
-
- let mix_left_and_right = |leftv: S::Larger, rightv: S::Larger| {
- <S as NumCast>::from(
- fact_left * leftv.to_f32().unwrap() + fact_right * rightv.to_f32().unwrap(),
- )
- .expect("Average sample value should fit into sample type")
- };
-
- (
- mix_left_and_right(sum_left.0, sum_right.0),
- mix_left_and_right(sum_left.1, sum_right.1),
- mix_left_and_right(sum_left.2, sum_right.2),
- mix_left_and_right(sum_left.3, sum_right.3),
- )
-}
-
-/// Get a thumbnail pixel where the input window encloses at least a horizontal pixel.
-fn thumbnail_sample_fraction_vertical<I, P, S>(
- image: &I,
- left: u32,
- right: u32,
- bottom: u32,
- fraction_vertical: f32,
-) -> (S, S, S, S)
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S>,
- S: Primitive + Enlargeable,
-{
- let fract = fraction_vertical;
-
- let mut sum_bot = ThumbnailSum::zeroed();
- let mut sum_top = ThumbnailSum::zeroed();
- for x in left..right {
- let k_bot = image.get_pixel(x, bottom);
- sum_bot.add_pixel(k_bot);
-
- let k_top = image.get_pixel(x, bottom + 1);
- sum_top.add_pixel(k_top);
- }
-
- // Now we approximate: bot/n*fract + top/n*(1-fract)
- let fact_top = fract / ((right - left) as f32);
- let fact_bot = (1. - fract) / ((right - left) as f32);
-
- let mix_bot_and_top = |botv: S::Larger, topv: S::Larger| {
- <S as NumCast>::from(fact_bot * botv.to_f32().unwrap() + fact_top * topv.to_f32().unwrap())
- .expect("Average sample value should fit into sample type")
- };
-
- (
- mix_bot_and_top(sum_bot.0, sum_top.0),
- mix_bot_and_top(sum_bot.1, sum_top.1),
- mix_bot_and_top(sum_bot.2, sum_top.2),
- mix_bot_and_top(sum_bot.3, sum_top.3),
- )
-}
-
-/// Get a single pixel for a thumbnail where the input window does not enclose any full pixel.
-fn thumbnail_sample_fraction_both<I, P, S>(
- image: &I,
- left: u32,
- fraction_vertical: f32,
- bottom: u32,
- fraction_horizontal: f32,
-) -> (S, S, S, S)
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S>,
- S: Primitive + Enlargeable,
-{
- #[allow(deprecated)]
- let k_bl = image.get_pixel(left, bottom).channels4();
- #[allow(deprecated)]
- let k_tl = image.get_pixel(left, bottom + 1).channels4();
- #[allow(deprecated)]
- let k_br = image.get_pixel(left + 1, bottom).channels4();
- #[allow(deprecated)]
- let k_tr = image.get_pixel(left + 1, bottom + 1).channels4();
-
- let frac_v = fraction_vertical;
- let frac_h = fraction_horizontal;
-
- let fact_tr = frac_v * frac_h;
- let fact_tl = frac_v * (1. - frac_h);
- let fact_br = (1. - frac_v) * frac_h;
- let fact_bl = (1. - frac_v) * (1. - frac_h);
-
- let mix = |br: S, tr: S, bl: S, tl: S| {
- <S as NumCast>::from(
- fact_br * br.to_f32().unwrap()
- + fact_tr * tr.to_f32().unwrap()
- + fact_bl * bl.to_f32().unwrap()
- + fact_tl * tl.to_f32().unwrap(),
- )
- .expect("Average sample value should fit into sample type")
- };
-
- (
- mix(k_br.0, k_tr.0, k_bl.0, k_tl.0),
- mix(k_br.1, k_tr.1, k_bl.1, k_tl.1),
- mix(k_br.2, k_tr.2, k_bl.2, k_tl.2),
- mix(k_br.3, k_tr.3, k_bl.3, k_tl.3),
- )
-}
-
-/// Perform a 3x3 box filter on the supplied image.
-/// ```kernel``` is an array of the filter weights of length 9.
-pub fn filter3x3<I, P, S>(image: &I, kernel: &[f32]) -> ImageBuffer<P, Vec<S>>
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S> + 'static,
- S: Primitive + 'static,
-{
- // The kernel's input positions relative to the current pixel.
- let taps: &[(isize, isize)] = &[
- (-1, -1),
- (0, -1),
- (1, -1),
- (-1, 0),
- (0, 0),
- (1, 0),
- (-1, 1),
- (0, 1),
- (1, 1),
- ];
-
- let (width, height) = image.dimensions();
-
- let mut out = ImageBuffer::new(width, height);
-
- let max = S::DEFAULT_MAX_VALUE;
- let max: f32 = NumCast::from(max).unwrap();
-
- let sum = match kernel.iter().fold(0.0, |s, &item| s + item) {
- x if x == 0.0 => 1.0,
- sum => sum,
- };
- let sum = (sum, sum, sum, sum);
-
- for y in 1..height - 1 {
- for x in 1..width - 1 {
- let mut t = (0.0, 0.0, 0.0, 0.0);
-
- // TODO: There is no need to recalculate the kernel for each pixel.
- // Only a subtract and addition is needed for pixels after the first
- // in each row.
- for (&k, &(a, b)) in kernel.iter().zip(taps.iter()) {
- let k = (k, k, k, k);
- let x0 = x as isize + a;
- let y0 = y as isize + b;
-
- let p = image.get_pixel(x0 as u32, y0 as u32);
-
- #[allow(deprecated)]
- let (k1, k2, k3, k4) = p.channels4();
-
- let vec: (f32, f32, f32, f32) = (
- NumCast::from(k1).unwrap(),
- NumCast::from(k2).unwrap(),
- NumCast::from(k3).unwrap(),
- NumCast::from(k4).unwrap(),
- );
-
- t.0 += vec.0 * k.0;
- t.1 += vec.1 * k.1;
- t.2 += vec.2 * k.2;
- t.3 += vec.3 * k.3;
- }
-
- let (t1, t2, t3, t4) = (t.0 / sum.0, t.1 / sum.1, t.2 / sum.2, t.3 / sum.3);
-
- #[allow(deprecated)]
- let t = Pixel::from_channels(
- NumCast::from(clamp(t1, 0.0, max)).unwrap(),
- NumCast::from(clamp(t2, 0.0, max)).unwrap(),
- NumCast::from(clamp(t3, 0.0, max)).unwrap(),
- NumCast::from(clamp(t4, 0.0, max)).unwrap(),
- );
-
- out.put_pixel(x, y, t);
- }
- }
-
- out
-}
-
-/// Resize the supplied image to the specified dimensions.
-/// ```nwidth``` and ```nheight``` are the new dimensions.
-/// ```filter``` is the sampling filter to use.
-pub fn resize<I: GenericImageView>(
- image: &I,
- nwidth: u32,
- nheight: u32,
- filter: FilterType,
-) -> ImageBuffer<I::Pixel, Vec<<I::Pixel as Pixel>::Subpixel>>
-where
- I::Pixel: 'static,
- <I::Pixel as Pixel>::Subpixel: 'static,
-{
- // check if the new dimensions are the same as the old. if they are, make a copy instead of resampling
- if (nwidth, nheight) == image.dimensions() {
- let mut tmp = ImageBuffer::new(image.width(), image.height());
- tmp.copy_from(image, 0, 0).unwrap();
- return tmp;
- }
-
- let mut method = match filter {
- FilterType::Nearest => Filter {
- kernel: Box::new(box_kernel),
- support: 0.0,
- },
- FilterType::Triangle => Filter {
- kernel: Box::new(triangle_kernel),
- support: 1.0,
- },
- FilterType::CatmullRom => Filter {
- kernel: Box::new(catmullrom_kernel),
- support: 2.0,
- },
- FilterType::Gaussian => Filter {
- kernel: Box::new(gaussian_kernel),
- support: 3.0,
- },
- FilterType::Lanczos3 => Filter {
- kernel: Box::new(lanczos3_kernel),
- support: 3.0,
- },
- };
-
- // Note: tmp is not necessarily actually Rgba
- let tmp: Rgba32FImage = vertical_sample(image, nheight, &mut method);
- horizontal_sample(&tmp, nwidth, &mut method)
-}
-
-/// Performs a Gaussian blur on the supplied image.
-/// ```sigma``` is a measure of how much to blur by.
-pub fn blur<I: GenericImageView>(
- image: &I,
- sigma: f32,
-) -> ImageBuffer<I::Pixel, Vec<<I::Pixel as Pixel>::Subpixel>>
-where
- I::Pixel: 'static,
-{
- let sigma = if sigma <= 0.0 { 1.0 } else { sigma };
-
- let mut method = Filter {
- kernel: Box::new(|x| gaussian(x, sigma)),
- support: 2.0 * sigma,
- };
-
- let (width, height) = image.dimensions();
-
- // Keep width and height the same for horizontal and
- // vertical sampling.
- // Note: tmp is not necessarily actually Rgba
- let tmp: Rgba32FImage = vertical_sample(image, height, &mut method);
- horizontal_sample(&tmp, width, &mut method)
-}
-
-/// Performs an unsharpen mask on the supplied image.
-/// ```sigma``` is the amount to blur the image by.
-/// ```threshold``` is the threshold for minimal brightness change that will be sharpened.
-///
-/// See <https://en.wikipedia.org/wiki/Unsharp_masking#Digital_unsharp_masking>
-pub fn unsharpen<I, P, S>(image: &I, sigma: f32, threshold: i32) -> ImageBuffer<P, Vec<S>>
-where
- I: GenericImageView<Pixel = P>,
- P: Pixel<Subpixel = S> + 'static,
- S: Primitive + 'static,
-{
- let mut tmp = blur(image, sigma);
-
- let max = S::DEFAULT_MAX_VALUE;
- let max: i32 = NumCast::from(max).unwrap();
- let (width, height) = image.dimensions();
-
- for y in 0..height {
- for x in 0..width {
- let a = image.get_pixel(x, y);
- let b = tmp.get_pixel_mut(x, y);
-
- let p = a.map2(b, |c, d| {
- let ic: i32 = NumCast::from(c).unwrap();
- let id: i32 = NumCast::from(d).unwrap();
-
- let diff = (ic - id).abs();
-
- if diff > threshold {
- let e = clamp(ic + diff, 0, max); // FIXME what does this do for f32? clamp 0-1 integers??
-
- NumCast::from(e).unwrap()
- } else {
- c
- }
- });
-
- *b = p;
- }
- }
-
- tmp
-}
-
-#[cfg(test)]
-mod tests {
- use super::{resize, sample_bilinear, sample_nearest, FilterType};
- use crate::{GenericImageView, ImageBuffer, RgbImage};
- #[cfg(feature = "benchmarks")]
- use test;
-
- #[bench]
- #[cfg(all(feature = "benchmarks", feature = "png"))]
- fn bench_resize(b: &mut test::Bencher) {
- use std::path::Path;
- let img = crate::open(&Path::new("./examples/fractal.png")).unwrap();
- b.iter(|| {
- test::black_box(resize(&img, 200, 200, FilterType::Nearest));
- });
- b.bytes = 800 * 800 * 3 + 200 * 200 * 3;
- }
-
- #[test]
- #[cfg(feature = "png")]
- fn test_resize_same_size() {
- use std::path::Path;
- let img = crate::open(&Path::new("./examples/fractal.png")).unwrap();
- let resize = img.resize(img.width(), img.height(), FilterType::Triangle);
- assert!(img.pixels().eq(resize.pixels()))
- }
-
- #[test]
- #[cfg(feature = "png")]
- fn test_sample_bilinear() {
- use std::path::Path;
- let img = crate::open(&Path::new("./examples/fractal.png")).unwrap();
- assert!(sample_bilinear(&img, 0., 0.).is_some());
- assert!(sample_bilinear(&img, 1., 0.).is_some());
- assert!(sample_bilinear(&img, 0., 1.).is_some());
- assert!(sample_bilinear(&img, 1., 1.).is_some());
- assert!(sample_bilinear(&img, 0.5, 0.5).is_some());
-
- assert!(sample_bilinear(&img, 1.2, 0.5).is_none());
- assert!(sample_bilinear(&img, 0.5, 1.2).is_none());
- assert!(sample_bilinear(&img, 1.2, 1.2).is_none());
-
- assert!(sample_bilinear(&img, -0.1, 0.2).is_none());
- assert!(sample_bilinear(&img, 0.2, -0.1).is_none());
- assert!(sample_bilinear(&img, -0.1, -0.1).is_none());
- }
- #[test]
- #[cfg(feature = "png")]
- fn test_sample_nearest() {
- use std::path::Path;
- let img = crate::open(&Path::new("./examples/fractal.png")).unwrap();
- assert!(sample_nearest(&img, 0., 0.).is_some());
- assert!(sample_nearest(&img, 1., 0.).is_some());
- assert!(sample_nearest(&img, 0., 1.).is_some());
- assert!(sample_nearest(&img, 1., 1.).is_some());
- assert!(sample_nearest(&img, 0.5, 0.5).is_some());
-
- assert!(sample_nearest(&img, 1.2, 0.5).is_none());
- assert!(sample_nearest(&img, 0.5, 1.2).is_none());
- assert!(sample_nearest(&img, 1.2, 1.2).is_none());
-
- assert!(sample_nearest(&img, -0.1, 0.2).is_none());
- assert!(sample_nearest(&img, 0.2, -0.1).is_none());
- assert!(sample_nearest(&img, -0.1, -0.1).is_none());
- }
- #[test]
- fn test_sample_bilinear_correctness() {
- use crate::Rgba;
- let img = ImageBuffer::from_fn(2, 2, |x, y| match (x, y) {
- (0, 0) => Rgba([255, 0, 0, 0]),
- (0, 1) => Rgba([0, 255, 0, 0]),
- (1, 0) => Rgba([0, 0, 255, 0]),
- (1, 1) => Rgba([0, 0, 0, 255]),
- _ => panic!(),
- });
- assert_eq!(sample_bilinear(&img, 0.5, 0.5), Some(Rgba([64; 4])));
- assert_eq!(sample_bilinear(&img, 0.0, 0.0), Some(Rgba([255, 0, 0, 0])));
- assert_eq!(sample_bilinear(&img, 0.0, 1.0), Some(Rgba([0, 255, 0, 0])));
- assert_eq!(sample_bilinear(&img, 1.0, 0.0), Some(Rgba([0, 0, 255, 0])));
- assert_eq!(sample_bilinear(&img, 1.0, 1.0), Some(Rgba([0, 0, 0, 255])));
-
- assert_eq!(
- sample_bilinear(&img, 0.5, 0.0),
- Some(Rgba([128, 0, 128, 0]))
- );
- assert_eq!(
- sample_bilinear(&img, 0.0, 0.5),
- Some(Rgba([128, 128, 0, 0]))
- );
- assert_eq!(
- sample_bilinear(&img, 0.5, 1.0),
- Some(Rgba([0, 128, 0, 128]))
- );
- assert_eq!(
- sample_bilinear(&img, 1.0, 0.5),
- Some(Rgba([0, 0, 128, 128]))
- );
- }
- #[test]
- fn test_sample_nearest_correctness() {
- use crate::Rgba;
- let img = ImageBuffer::from_fn(2, 2, |x, y| match (x, y) {
- (0, 0) => Rgba([255, 0, 0, 0]),
- (0, 1) => Rgba([0, 255, 0, 0]),
- (1, 0) => Rgba([0, 0, 255, 0]),
- (1, 1) => Rgba([0, 0, 0, 255]),
- _ => panic!(),
- });
-
- assert_eq!(sample_nearest(&img, 0.0, 0.0), Some(Rgba([255, 0, 0, 0])));
- assert_eq!(sample_nearest(&img, 0.0, 1.0), Some(Rgba([0, 255, 0, 0])));
- assert_eq!(sample_nearest(&img, 1.0, 0.0), Some(Rgba([0, 0, 255, 0])));
- assert_eq!(sample_nearest(&img, 1.0, 1.0), Some(Rgba([0, 0, 0, 255])));
-
- assert_eq!(sample_nearest(&img, 0.5, 0.5), Some(Rgba([0, 0, 0, 255])));
- assert_eq!(sample_nearest(&img, 0.5, 0.0), Some(Rgba([0, 0, 255, 0])));
- assert_eq!(sample_nearest(&img, 0.0, 0.5), Some(Rgba([0, 255, 0, 0])));
- assert_eq!(sample_nearest(&img, 0.5, 1.0), Some(Rgba([0, 0, 0, 255])));
- assert_eq!(sample_nearest(&img, 1.0, 0.5), Some(Rgba([0, 0, 0, 255])));
- }
-
- #[bench]
- #[cfg(all(feature = "benchmarks", feature = "tiff"))]
- fn bench_resize_same_size(b: &mut test::Bencher) {
- let path = concat!(
- env!("CARGO_MANIFEST_DIR"),
- "/tests/images/tiff/testsuite/mandrill.tiff"
- );
- let image = crate::open(path).unwrap();
- b.iter(|| {
- test::black_box(image.resize(image.width(), image.height(), FilterType::CatmullRom));
- });
- b.bytes = (image.width() * image.height() * 3) as u64;
- }
-
- #[test]
- fn test_issue_186() {
- let img: RgbImage = ImageBuffer::new(100, 100);
- let _ = resize(&img, 50, 50, FilterType::Lanczos3);
- }
-
- #[bench]
- #[cfg(all(feature = "benchmarks", feature = "tiff"))]
- fn bench_thumbnail(b: &mut test::Bencher) {
- let path = concat!(
- env!("CARGO_MANIFEST_DIR"),
- "/tests/images/tiff/testsuite/mandrill.tiff"
- );
- let image = crate::open(path).unwrap();
- b.iter(|| {
- test::black_box(image.thumbnail(256, 256));
- });
- b.bytes = 512 * 512 * 4 + 256 * 256 * 4;
- }
-
- #[bench]
- #[cfg(all(feature = "benchmarks", feature = "tiff"))]
- fn bench_thumbnail_upsize(b: &mut test::Bencher) {
- let path = concat!(
- env!("CARGO_MANIFEST_DIR"),
- "/tests/images/tiff/testsuite/mandrill.tiff"
- );
- let image = crate::open(path).unwrap().thumbnail(256, 256);
- b.iter(|| {
- test::black_box(image.thumbnail(512, 512));
- });
- b.bytes = 512 * 512 * 4 + 256 * 256 * 4;
- }
-
- #[bench]
- #[cfg(all(feature = "benchmarks", feature = "tiff"))]
- fn bench_thumbnail_upsize_irregular(b: &mut test::Bencher) {
- let path = concat!(
- env!("CARGO_MANIFEST_DIR"),
- "/tests/images/tiff/testsuite/mandrill.tiff"
- );
- let image = crate::open(path).unwrap().thumbnail(193, 193);
- b.iter(|| {
- test::black_box(image.thumbnail(256, 256));
- });
- b.bytes = 193 * 193 * 4 + 256 * 256 * 4;
- }
-
- #[test]
- #[cfg(feature = "png")]
- fn resize_transparent_image() {
- use super::FilterType::{CatmullRom, Gaussian, Lanczos3, Nearest, Triangle};
- use crate::imageops::crop_imm;
- use crate::RgbaImage;
-
- fn assert_resize(image: &RgbaImage, filter: FilterType) {
- let resized = resize(image, 16, 16, filter);
- let cropped = crop_imm(&resized, 5, 5, 6, 6).to_image();
- for pixel in cropped.pixels() {
- let alpha = pixel.0[3];
- assert!(
- alpha != 254 && alpha != 253,
- "alpha value: {}, {:?}",
- alpha,
- filter
- );
- }
- }
-
- let path = concat!(
- env!("CARGO_MANIFEST_DIR"),
- "/tests/images/png/transparency/tp1n3p08.png"
- );
- let img = crate::open(path).unwrap();
- let rgba8 = img.as_rgba8().unwrap();
- let filters = &[Nearest, Triangle, CatmullRom, Gaussian, Lanczos3];
- for filter in filters {
- assert_resize(rgba8, *filter);
- }
- }
-
- #[test]
- fn bug_1600() {
- let image = crate::RgbaImage::from_raw(629, 627, vec![255; 629 * 627 * 4]).unwrap();
- let result = resize(&image, 22, 22, FilterType::Lanczos3);
- assert!(result.into_raw().into_iter().any(|c| c != 0));
- }
-}