修改 svg 图片颜色

使用 <img> 标签或 background-image 引入 svg 图片
使用以下 html 文件，得到 filter 值

html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .pixel {
      display: inline-block;
      background-color: #000;
      width: 50px;
      height: 50px;
    }

    .filterDetail {
      font-family: "Consolas", "Menlo", "Ubuntu Mono", monospace;
    }
  </style>
</head>

<body>
  <table>
    <tr valign="top">
      <td width="50%">
        <fieldset>
          <p>
            <label>Target color</label> <input class="target" type="text" placeholder="target hex" value="#00a4d6" />
          </p>
          <button class="execute">Compute Filters</button>
        </fieldset>
        <p>Real pixel, color applied through CSS <code>background-color</code>:</p>
        <div class="pixel realPixel"></div>

        <p>Filtered pixel, color applied through CSS <code>filter</code>:</p>
        <div class="pixel filterPixel"></div>

        <p class="filterDetail"></p>
        <p class="lossDetail"></p>
      </td>
    </tr>
  </table>

  <script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
  <script>
    'use strict';

    class Color {
      constructor(r, g, b) {
        this.set(r, g, b);
      }

      toString() {
        return `rgb(${Math.round(this.r)}, ${Math.round(this.g)}, ${Math.round(this.b)})`;
      }

      set(r, g, b) {
        this.r = this.clamp(r);
        this.g = this.clamp(g);
        this.b = this.clamp(b);
      }

      hueRotate(angle = 0) {
        angle = angle / 180 * Math.PI;
        const sin = Math.sin(angle);
        const cos = Math.cos(angle);

        this.multiply([
          0.213 + cos * 0.787 - sin * 0.213,
          0.715 - cos * 0.715 - sin * 0.715,
          0.072 - cos * 0.072 + sin * 0.928,
          0.213 - cos * 0.213 + sin * 0.143,
          0.715 + cos * 0.285 + sin * 0.140,
          0.072 - cos * 0.072 - sin * 0.283,
          0.213 - cos * 0.213 - sin * 0.787,
          0.715 - cos * 0.715 + sin * 0.715,
          0.072 + cos * 0.928 + sin * 0.072,
        ]);
      }

      grayscale(value = 1) {
        this.multiply([
          0.2126 + 0.7874 * (1 - value),
          0.7152 - 0.7152 * (1 - value),
          0.0722 - 0.0722 * (1 - value),
          0.2126 - 0.2126 * (1 - value),
          0.7152 + 0.2848 * (1 - value),
          0.0722 - 0.0722 * (1 - value),
          0.2126 - 0.2126 * (1 - value),
          0.7152 - 0.7152 * (1 - value),
          0.0722 + 0.9278 * (1 - value),
        ]);
      }

      sepia(value = 1) {
        this.multiply([
          0.393 + 0.607 * (1 - value),
          0.769 - 0.769 * (1 - value),
          0.189 - 0.189 * (1 - value),
          0.349 - 0.349 * (1 - value),
          0.686 + 0.314 * (1 - value),
          0.168 - 0.168 * (1 - value),
          0.272 - 0.272 * (1 - value),
          0.534 - 0.534 * (1 - value),
          0.131 + 0.869 * (1 - value),
        ]);
      }

      saturate(value = 1) {
        this.multiply([
          0.213 + 0.787 * value,
          0.715 - 0.715 * value,
          0.072 - 0.072 * value,
          0.213 - 0.213 * value,
          0.715 + 0.285 * value,
          0.072 - 0.072 * value,
          0.213 - 0.213 * value,
          0.715 - 0.715 * value,
          0.072 + 0.928 * value,
        ]);
      }

      multiply(matrix) {
        const newR = this.clamp(this.r * matrix[0] + this.g * matrix[1] + this.b * matrix[2]);
        const newG = this.clamp(this.r * matrix[3] + this.g * matrix[4] + this.b * matrix[5]);
        const newB = this.clamp(this.r * matrix[6] + this.g * matrix[7] + this.b * matrix[8]);
        this.r = newR;
        this.g = newG;
        this.b = newB;
      }

      brightness(value = 1) {
        this.linear(value);
      }
      contrast(value = 1) {
        this.linear(value, -(0.5 * value) + 0.5);
      }

      linear(slope = 1, intercept = 0) {
        this.r = this.clamp(this.r * slope + intercept * 255);
        this.g = this.clamp(this.g * slope + intercept * 255);
        this.b = this.clamp(this.b * slope + intercept * 255);
      }

      invert(value = 1) {
        this.r = this.clamp((value + this.r / 255 * (1 - 2 * value)) * 255);
        this.g = this.clamp((value + this.g / 255 * (1 - 2 * value)) * 255);
        this.b = this.clamp((value + this.b / 255 * (1 - 2 * value)) * 255);
      }

      hsl() {
        // Code taken from https://stackoverflow.com/a/9493060/2688027, licensed under CC BY-SA.
        const r = this.r / 255;
        const g = this.g / 255;
        const b = this.b / 255;
        const max = Math.max(r, g, b);
        const min = Math.min(r, g, b);
        let h, s, l = (max + min) / 2;

        if (max === min) {
          h = s = 0;
        } else {
          const d = max - min;
          s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
          switch (max) {
            case r:
              h = (g - b) / d + (g < b ? 6 : 0);
              break;

            case g:
              h = (b - r) / d + 2;
              break;

            case b:
              h = (r - g) / d + 4;
              break;
          }
          h /= 6;
        }

        return {
          h: h * 100,
          s: s * 100,
          l: l * 100,
        };
      }

      clamp(value) {
        if (value > 255) {
          value = 255;
        } else if (value < 0) {
          value = 0;
        }
        return value;
      }
    }

    class Solver {
      constructor(target, baseColor) {
        this.target = target;
        this.targetHSL = target.hsl();
        this.reusedColor = new Color(0, 0, 0);
      }

      solve() {
        const result = this.solveNarrow(this.solveWide());
        return {
          values: result.values,
          loss: result.loss,
          filter: this.css(result.values),
        };
      }

      solveWide() {
        const A = 5;
        const c = 15;
        const a = [60, 180, 18000, 600, 1.2, 1.2];

        let best = { loss: Infinity };
        for (let i = 0; best.loss > 25 && i < 3; i++) {
          const initial = [50, 20, 3750, 50, 100, 100];
          const result = this.spsa(A, a, c, initial, 1000);
          if (result.loss < best.loss) {
            best = result;
          }
        }
        return best;
      }

      solveNarrow(wide) {
        const A = wide.loss;
        const c = 2;
        const A1 = A + 1;
        const a = [0.25 * A1, 0.25 * A1, A1, 0.25 * A1, 0.2 * A1, 0.2 * A1];
        return this.spsa(A, a, c, wide.values, 500);
      }

      spsa(A, a, c, values, iters) {
        const alpha = 1;
        const gamma = 0.16666666666666666;

        let best = null;
        let bestLoss = Infinity;
        const deltas = new Array(6);
        const highArgs = new Array(6);
        const lowArgs = new Array(6);

        for (let k = 0; k < iters; k++) {
          const ck = c / Math.pow(k + 1, gamma);
          for (let i = 0; i < 6; i++) {
            deltas[i] = Math.random() > 0.5 ? 1 : -1;
            highArgs[i] = values[i] + ck * deltas[i];
            lowArgs[i] = values[i] - ck * deltas[i];
          }

          const lossDiff = this.loss(highArgs) - this.loss(lowArgs);
          for (let i = 0; i < 6; i++) {
            const g = lossDiff / (2 * ck) * deltas[i];
            const ak = a[i] / Math.pow(A + k + 1, alpha);
            values[i] = fix(values[i] - ak * g, i);
          }

          const loss = this.loss(values);
          if (loss < bestLoss) {
            best = values.slice(0);
            bestLoss = loss;
          }
        }
        return { values: best, loss: bestLoss };

        function fix(value, idx) {
          let max = 100;
          if (idx === 2 /* saturate */) {
            max = 7500;
          } else if (idx === 4 /* brightness */ || idx === 5 /* contrast */) {
            max = 200;
          }

          if (idx === 3 /* hue-rotate */) {
            if (value > max) {
              value %= max;
            } else if (value < 0) {
              value = max + value % max;
            }
          } else if (value < 0) {
            value = 0;
          } else if (value > max) {
            value = max;
          }
          return value;
        }
      }

      loss(filters) {
        // Argument is array of percentages.
        const color = this.reusedColor;
        color.set(0, 0, 0);

        color.invert(filters[0] / 100);
        color.sepia(filters[1] / 100);
        color.saturate(filters[2] / 100);
        color.hueRotate(filters[3] * 3.6);
        color.brightness(filters[4] / 100);
        color.contrast(filters[5] / 100);

        const colorHSL = color.hsl();
        return (
          Math.abs(color.r - this.target.r) +
          Math.abs(color.g - this.target.g) +
          Math.abs(color.b - this.target.b) +
          Math.abs(colorHSL.h - this.targetHSL.h) +
          Math.abs(colorHSL.s - this.targetHSL.s) +
          Math.abs(colorHSL.l - this.targetHSL.l)
        );
      }

      css(filters) {
        function fmt(idx, multiplier = 1) {
          return Math.round(filters[idx] * multiplier);
        }
        return `filter: invert(${fmt(0)}%) sepia(${fmt(1)}%) saturate(${fmt(2)}%) hue-rotate(${fmt(3, 3.6)}deg) brightness(${fmt(4)}%) contrast(${fmt(5)}%);`;
      }
    }

    function hexToRgb(hex) {
      // Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")
      const shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;
      hex = hex.replace(shorthandRegex, (m, r, g, b) => {
        return r + r + g + g + b + b;
      });

      const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
      return result
        ? [
          parseInt(result[1], 16),
          parseInt(result[2], 16),
          parseInt(result[3], 16),
        ]
        : null;
    }

    $(document).ready(() => {
      $('button.execute').click(() => {
        const rgb = hexToRgb($('input.target').val());
        if (rgb.length !== 3) {
          alert('Invalid format!');
          return;
        }

        const color = new Color(rgb[0], rgb[1], rgb[2]);
        const solver = new Solver(color);
        const result = solver.solve();

        let lossMsg;
        if (result.loss < 1) {
          lossMsg = 'This is a perfect result.';
        } else if (result.loss < 5) {
          lossMsg = 'The is close enough.';
        } else if (result.loss < 15) {
          lossMsg = 'The color is somewhat off. Consider running it again.';
        } else {
          lossMsg = 'The color is extremely off. Run it again!';
        }

        $('.realPixel').css('background-color', color.toString());
        $('.filterPixel').attr('style', result.filter);
        $('.filterDetail').text(result.filter);
        $('.lossDetail').html(`Loss: ${result.loss.toFixed(1)}. <b>${lossMsg}</b>`);
      });
    });
  </script>
</body>

</html>

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使用得出的 filter 值即可转换颜色

修改 svg 图片颜色 ​

修改 svg 图片颜色