mirror of
https://github.com/lovell/sharp.git
synced 2025-07-14 04:40:13 +02:00
35 lines
1.0 KiB
JavaScript
35 lines
1.0 KiB
JavaScript
'use strict';
|
|
/*jshint esversion: 6 */
|
|
|
|
const fs = require('fs');
|
|
const child_process = require('child_process');
|
|
|
|
const a = [];
|
|
const b = [];
|
|
|
|
fs.readdirSync('./images')
|
|
.filter((file) => file.endsWith('.jpg'))
|
|
.forEach((file) => {
|
|
// Extract one pixel, avoiding first DCT block, and return value of A and B channels
|
|
const command = `convert ./images/${file}[1x1+8+8] -colorspace lab -format "%[fx:u.g] %[fx:u.b]" info:`;
|
|
const result = child_process.execSync(command, { encoding: 'utf8' });
|
|
const ab = result.split(' ');
|
|
a.push(ab[0]);
|
|
b.push(ab[1]);
|
|
});
|
|
|
|
a.sort((v1, v2) => v1 - v2);
|
|
b.sort((v1, v2) => v1 - v2);
|
|
|
|
// Convert from 0..1 to -128..128
|
|
const convert = function(v) {
|
|
return Math.round(256 * (v - 0.5));
|
|
};
|
|
|
|
const threshold = Math.round(a.length / 100);
|
|
console.log(`Trimming lowest/highest ${threshold} for 98th percentile`);
|
|
|
|
// Ignore ~2% outliers
|
|
console.log(`a ${convert(a[threshold])} - ${convert(a[a.length - threshold])}`);
|
|
console.log(`b ${convert(b[threshold])} - ${convert(b[b.length - threshold])}`);
|