Struct AutoContrast

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pub struct AutoContrast { /* private fields */ }

Expand description

Automatically determines display range by scanning the image.

Must be constructed via AutoContrast::new(), AutoContrast::scan(), or AutoContrast::scan_with().

This strategy applies sRGB gamma encoding after range mapping: values at min map to black, values at max map to white.

§Supported pixel types

AutoContrast implements DisplayStrategy for single-channel types: Mono8, Mono16, Mono32, Mono64, Mono<10>, Mono<12>, Mono<14>, f32, f64, u8, u16.

For multi-channel types (RGB, etc.), what “auto contrast” means is ambiguous. Use LinearToDisplay or a custom strategy instead.

§Examples

use fovea::pixel::{Mono16, Srgba8};
use fovea_display::{DisplayStrategy, AutoContrast};

let ac = AutoContrast::new(0.0, 65535.0);
assert_eq!(ac.to_display(&Mono16::new(0)), Srgba8::new(0, 0, 0, 255));
assert_eq!(ac.to_display(&Mono16::new(65535)), Srgba8::new(255, 255, 255, 255));

Implementations§

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impl AutoContrast

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pub fn new(min: f64, max: f64) -> Self

Create an AutoContrast with an explicit min/max range.

Values at min map to black, values at max map to white. If min == max, all pixels map to mid-gray.

Source

pub fn scan<V>(image: &V) -> Self
where V: ImageView, V::Pixel: Copy + Into<f64>,

Scan an image to determine the display range.

Iterates all pixels, converting each to f64 via Into<f64>, and finds the minimum and maximum values.

§Type bounds

Requires V::Pixel: Into<f64>. For pixel types that don’t implement Into<f64> (e.g. Mono<BITS>), use AutoContrast::scan_with() instead.

§Panics

Returns a degenerate (mid-gray) range for empty images.

§Examples

use fovea::image::{Image, ImageView};
use fovea::pixel::{MonoF32, Srgba8};
use fovea_display::{DisplayStrategy, AutoContrast};

// pixel role for floats is `MonoF32`, not `f32`.
let img = Image::<MonoF32>::fill(4, 4, MonoF32::new(0.5));
let ac = AutoContrast::scan(&img);
// Constant image → degenerate range → mid-gray
assert_eq!(ac.to_display(&MonoF32::new(0.5)), Srgba8::new(128, 128, 128, 255));

Source

pub fn scan_with<V, F>(image: &V, to_scalar: F) -> Self
where V: ImageView, V::Pixel: Copy, F: Fn(&V::Pixel) -> f64,

Scan an image to determine the display range using a custom scalar extraction function.

This is the general-purpose constructor that works with any pixel type, including Mono<BITS> and other types without Into<f64>.

§Examples

use fovea::image::{Image, ImageView, ImageViewMut};
use fovea::pixel::{Mono16, Srgba8};
use fovea_display::{DisplayStrategy, AutoContrast};

let mut img = Image::<Mono16>::fill(4, 4, Mono16::new(100));
*img.get_mut(0, 0).unwrap() = Mono16::new(50);
*img.get_mut(3, 3).unwrap() = Mono16::new(200);

let ac = AutoContrast::scan_with(&img, |p| p.value() as f64);
assert_eq!(ac.to_display(&Mono16::new(50)), Srgba8::new(0, 0, 0, 255));
assert_eq!(ac.to_display(&Mono16::new(200)), Srgba8::new(255, 255, 255, 255));

Trait Implementations§

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impl Clone for AutoContrast

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fn clone(&self) -> AutoContrast

Returns a duplicate of the value. Read more

1.0.0 (const: unstable) · Source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

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impl Copy for AutoContrast

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