woodblock print 100-7289 from the Ukiyo-e.org database and image similarity analysis engine developed by @jeresig
a shameless iteration on @mbostock‘s Mona Lisa Histogram
🙏 to @Milr0c for showing me how to preserve access to an individual character of a string that happens to be inside of an expression embedded within a template literal, like this:
.attr('class', (d, i) => `histogram-area histogram-${'rgb'[i]}`);<!DOCTYPE html>
<meta charset="utf-8">
<style>
canvas,
svg {
position: absolute;
}
.brush .selection {
stroke: #fff;
stroke-opacity: 0.7;
shape-rendering: crispEdges;
}
.histogram {
pointer-events: none;
}
.histogram-panel {
fill: #111;
fill-opacity: 0.5;
stroke: #000;
}
.histogram-area {
mix-blend-mode: screen;
}
.histogram-area.histogram-r {
fill: #f00;
}
.histogram-area.histogram-g {
fill: #0f0;
}
.histogram-area.histogram-b {
fill: #00f;
}
.histogram-line {
fill: none;
stroke: #000;
stroke-width: 0.5px;
}
</style>
<canvas width="960" height="1452"></canvas>
<svg width="960" height="1452"></svg>
<script src="https://d3js.org/d3.v4.0.0-alpha.44.min.js"></script>
<script src="https://npmcdn.com/babel-core@5.8.34/browser.min.js"></script>
<script>
d3_color =
d3_dispatch =
d3_ease =
d3_interpolate =
d3_timer =
d3_selection =
d3_transition =
d3_drag = d3;
</script>
<script src="https://d3js.org/d3-brush.v0.1.min.js"></script>
<script lang='babel' type='text/babel'>
const canvas = document.querySelector('canvas');
const context = canvas.getContext('2d');
const width = canvas.width;
const height = canvas.height;
const histomargin = { top: 10, right: 10, bottom: 0, left: width - 256 - 10 };
const histowidth = width - histomargin.left - histomargin.right;
const histoheight = 256;
let r = d3.range(257).map(() => 0);
let g = d3.range(257).map(() => 0);
let b = d3.range(257).map(() => 0);
let x = (d, i) => i;
let y = d => histoheight - Math.round(d / n * 32 * histoheight);
let n = 1;
const area = d3.area()
.curve(d3.curveStepBefore)
.x(x)
.y0(y(0))
.y1(y);
const line = d3.line()
.curve(d3.curveStepBefore)
.x(x)
.y(y);
const brush = d3_brush.brush()
.on('start brush', brushed)
.on('end', brushended);
const svg = d3.select('svg');
const histogram = svg.append('g')
.attr('class', 'histogram')
.attr('transform', `translate(${histomargin.left}, ${histomargin.top})`);
histogram.append('rect')
.attr('class', 'histogram-panel')
.attr('x', -0.5)
.attr('y', -0.5)
.attr('width', histowidth + 1)
.attr('height', histoheight + 1);
const histoarea = histogram.selectAll('.histogram-area')
.data([r, g, b])
.enter().append('path')
.attr('class', (d, i) => `histogram-area histogram-${'rgb'[i]}`);
const histoline = histogram.selectAll('.histogram-line')
.data([r, g, b])
.enter().append('path')
.attr('class', (d, i) => `histogram-line histogram-${'rgb'[i]}`)
.attr('transform', 'translate(0.5,-0.5)');
const image = new Image;
image.src = '100-7289.jpg';
image.onload = loaded;
function loaded() {
context.drawImage(this, 0, 0, width, height);
svg.append('g')
.attr('class', 'brush')
.call(brush)
.call(brush.move, [[260, 228], [656, 600]]);
}
function brushed() {
const s = d3.event.selection;
x = s[0][0];
y = s[0][1];
const w = s[1][0] - x;
const h = s[1][1] - y;
for (let i = 0; i < 256; ++i) {
r[i] = g[i] = b[i] = 0;
}
n = w * h;
if (n) {
const data = context.getImageData(x, y, w, h).data;
for (let i = 0; i < w; ++i) {
for (let j = 0; j < h; ++j) {
const k = j * w + i << 2;
++r[data[k]];
++g[data[k + 1]];
++b[data[k + 2]];
}
}
histoarea.attr('d', area);
histoline.attr('d', line);
} else {
histoarea.attr('d', null);
histoline.attr('d', null);
}
}
function brushended() {
if (!d3.event.selection) {
histoarea.attr('d', null);
histoline.attr('d', null);
}
}
</script>