Brightness
This program adjusts the brightness of a part of the image by calculating the distance of each pixel to the mouse.
This example is ported from the Brightness example
on the Processing website
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// This program adjusts the brightness
// of a part of the image by
// calculating the distance of
// each pixel to the mouse.
let img;
// preload() runs once, before setup()
// loadImage() needs to occur here instead of setup()
// preload() makes sure image is loaded before anything else occurs
function preload() {
// load the original image
img = loadImage("assets/rover_wide.jpg");
}
// setup() runs after preload, once()
function setup() {
createCanvas(710, 400);
pixelDensity(1);
frameRate(30);
}
function draw() {
image(img,0,0);
// Only need to load the pixels[] array once, because we're only
// manipulating pixels[] inside draw(), not drawing shapes.
loadPixels();
// We must also call loadPixels() on the PImage since we are going to read its pixels.
img.loadPixels();
for (let x = 0; x < img.width; x++) {
for (let y = 0; y < img.height; y++ ) {
// Calculate the 1D location from a 2D grid
let loc = (x + y*img.width)*4;
// Get the R,G,B values from image
let r,g,b;
r = img.pixels[loc];
// g = img.pixels[loc+1];
// b = img.pixels[loc+2];
// Calculate an amount to change brightness based on proximity to the mouse
// The closer the pixel is to the mouse, the lower the value of "distance"
let maxdist = 50;//dist(0,0,width,height);
let d = dist(x, y, mouseX, mouseY);
let adjustbrightness = 255*(maxdist-d)/maxdist;
r += adjustbrightness;
// g += adjustbrightness;
// b += adjustbrightness;
// Constrain RGB to make sure they are within 0-255 color range
r = constrain(r, 0, 255);
// g = constrain(g, 0, 255);
// b = constrain(b, 0, 255);
// Make a new color and set pixel in the window
let pixloc = (y*width + x)*4;
pixels[pixloc] = r;
pixels[pixloc+1] = r;
pixels[pixloc+2] = r;
pixels[pixloc+3] = 255; // Always have to set alpha
}
}
updatePixels();
}
