Generate log2 LUT stimulus vertical strip

main.rs

// Generate log2 LUT stimulus

// [dependencies]
// image = "0.24"
// glam = "0.22"

use glam::{vec3, Vec3};
use image::{ImageBuffer, Rgb};
extern crate image;

fn convert_normalized_log2_to_open_domain(color: Vec3, minimum_ev: f32, maximum_ev: f32) -> Vec3 {
    let mut color = color;
    let in_midgrey = 0.18;
    let total_exposure = maximum_ev - minimum_ev;

    color = (color * total_exposure) + minimum_ev;
    color = vec3(
        (2.0_f32).powf(color.x),
        (2.0_f32).powf(color.y),
        (2.0_f32).powf(color.z),
    );
    color = color * in_midgrey;

    return color;
}

fn generate(block_size: u32, minimum_ev: f32, maximum_ev: f32) -> ImageBuffer<Rgb<f32>, Vec<f32>> {
    let imgx = block_size;
    let imgy = block_size * block_size;
    let m = 1.0 / (imgx as f32);

    // Create a new ImgBuf with width: imgx and height: imgy
    let mut imgbuf = image::ImageBuffer::new(imgx, imgy);

    // Iterate over the coordinates and pixels of the image
    for (x, y, pixel) in imgbuf.enumerate_pixels_mut() {
        let r = x as f32;
        let g = (y % block_size) as f32;
        let b = (y / block_size) as f32;

        let c = convert_normalized_log2_to_open_domain(
            vec3(r * m, g * m, b * m),
            minimum_ev,
            maximum_ev,
        );

        *pixel = image::Rgb([c.x, c.y, c.z]);
    }
    imgbuf
}

fn main() {
    generate(64, -11.0, 12.0)
        .save("empty_exp_lut_vert.exr")
        .unwrap();
}