//! # Ordered dithering.
//! The way this works is by adding a constant texture to the image, and then quantizing that.
use super::*;
pub fn remap_bayer_2x2(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
let r = kd.space(palette);
dither_with::<2>(image, |((x, y), &p)| {
let color = p.add(r * BAYER_2X2[x + y * 2]);
palette[kd.find_nearest(color) as usize]
})
}
pub fn remap_bayer_4x4(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
let r = kd.space(palette);
dither_with::<4>(image, |((x, y), &p)| {
let color = p.add(r * BAYER_4X4[x + y * 4]);
palette[kd.find_nearest(color) as usize]
})
}
pub fn remap_bayer_8x8(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
let r = kd.space(palette);
dither_with::<8>(image, |((x, y), &p)| {
let color = p.add(r * BAYER_8X8[x + y * 8]);
palette[kd.find_nearest(color) as usize]
})
}
pub fn remap(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
// todo!();
Image::build(image.width(), image.height()).buf(
image
.chunked()
.flat_map(|x| palette[kd.find_nearest(*x) as usize])
// .map(|&x| palette.closest(x).1)
.collect(),
)
}
const BLUE: Image<[f32; 1024 * 1024 * 3], 3> = unsafe {
Image::new(
std::num::NonZero::new(1024).unwrap(),
std::num::NonZero::new(1024).unwrap(),
std::mem::transmute(*include_bytes!("../blue.f32")),
)
};
// todo: figure this out? seems off.
pub fn remap_blue(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
// Image::<Box<[u8]>, 3>::from(BLUE.as_ref()).show();
dither(image, |((x, y), p)| {
let (p, al) = p.pop();
let noise = unsafe { BLUE.pixel(x as u32 % 1024, y as u32 % 1024) }.sub(0.5);
fn lin_to_srgb(x: f32) -> f32 {
if x.abs() <= 0.0031308 {
x * 12.92
} else {
(1.055 * x.abs().powf(1.0 / 2.4) - 0.055).copysign(x)
}
}
fn srgb_to_lin(x: f32) -> f32 {
if x.abs() <= 0.04045 {
x * (1.0 / 12.92)
} else {
((x.abs() + 0.055) * (1.0 / 1.055)).powf(2.4).copysign(x)
}
}
let c = p
.map(srgb_to_lin)
.zip(noise)
.map(|(x, noise)| x + noise)
.map(lin_to_srgb)
.join(al);
// let yuv = [
// p.amul([0.299, 0.587, 0.114]).sum(),
// p.amul([-0.14713, -0.28886, 0.436]).sum(),
// p.amul([0.615, -0.51499, -0.10001]).sum(),
// ];
// let c = yuv.zip(noise).map(|(x, noise)| x + noise);
// let c = [
// c.amul([1., 0., 1.13983]).sum(),
// c.amul([1., -0.39465, -0.58060]).sum(),
// c.amul([1., 2.03211, 0.]).sum(),
// ];
// let c = c.join(al);
palette[kd.find_nearest(c) as usize]
})
}
pub fn remap_triangular(image: Image<&[f32], 4>, palette: &[[f32; 4]]) -> Image<Box<[f32]>, 4> {
let kd = map(palette);
dither(image, |((x, y), p)| {
let (p, al) = p.pop();
let noise = unsafe { BLUE.pixel(x as u32 % 1024, y as u32 % 1024) };
let c = p
.zip(noise)
.map(|(x, noise)| {
let noise = if x < (0.5 / 255.) || x > (254.5 / 255.) {
noise - 0.5
} else {
if noise < 0.5 {
(2.0 * noise).sqrt() - 1.0
} else {
1.0 - (2.0 - 2.0 * noise).sqrt()
}
};
x + noise
})
.join(al);
palette[kd.find_nearest(c) as usize]
})
}