Public
Edited
Oct 24, 2023
4 forks
21 stars
Insert cell
Insert cell
Insert cell
canvas1 = DOM.canvas(width, height, 1)
Insert cell
update1 = {
const context = canvas1.getContext("2d");
context.drawImage(image, 0, 0);
const data = context.getImageData(0, 0, width, height);
d3.blurImage(data, r);
context.putImageData(data, 0, 0);
return htl.html`<em>Blurred with radius ${r}.`
}
Insert cell
Insert cell
Insert cell
Insert cell
canvas2 = DOM.canvas(width, height, 1)
Insert cell
update2 = {
const context = canvas2.getContext("2d");
context.drawImage(image, 0, 0);
const data = context.getImageData(0, 0, width, height);
d3.blurImage(data, rx, ry);
context.putImageData(data, 0, 0);
return htl.html`<em>Blurred with radii [${rx}, ${ry}].`
}
Insert cell
Insert cell
Insert cell
laplacianCanvas({image, gain: 20, radius: 0.5}) // contours
Insert cell
function laplacian(image, radius) {
const I = image.data;
const L = new Float32Array(I); // copy before blurring; allow negative values
d3.blurImage(image, radius);
for (let i = 0, n = I.length; i < n; ++i) {
if (i % 4 === 3) continue; // ignore the A channel of RGBA
L[i] -= I[i];
}
return L;
}
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
canvas4 = DOM.canvas(width, height, 1)
Insert cell
update4 = laplacianCanvas({image, canvas: canvas4, gain, alpha, radius: rl})
Insert cell
Insert cell
fuzziness = {
const canvas = DOM.canvas(width, height, 1);
const context = canvas.getContext("2d");
context.drawImage(image, 0, 0, width, height);
const L = laplacian(context.getImageData(0, 0, width, height), 0.5);
return [0, 1, 2].map(channel => d3.deviation(L, (d, i) => (i % 4 === channel ? d : NaN)));
}
Insert cell
Insert cell
function laplacianCanvas({
image,
width = image.naturalWidth,
height = image.naturalHeight,
canvas = DOM.canvas(width, height, 1),
gain = 1,
alpha = 0,
radius
}) {
const context = canvas.getContext("2d");
context.drawImage(image, 0, 0, width, height);
const imageData = context.getImageData(0, 0, width, height);
const L = laplacian(context.getImageData(0, 0, width, height), radius);
const {data: I} = imageData;
for (let i = 0, n = I.length; i < n; ++i) {
if (i % 4 === 3) continue; // skip: ignore the A channel of RGBA
I[i] = (1 - alpha) * 128 + alpha * I[i] + gain * L[i];
}
context.putImageData(imageData, 0, 0);
return canvas;
}
Insert cell
image = FileAttachment("shoreline-emily-carr.png").image({width: 48})
Insert cell
width = image.naturalWidth
Insert cell
height = image.naturalHeight
Insert cell

One platform to build and deploy the best data apps

Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.
Learn more