a);
                        }
                        diffs = diffs.sort((o1, o2) => o1 - o2).slice(Math.floor(diffs.length * 0.25), Math.floor(diffs.length * 0.75));
                        const sum = diffs.reduce((pre, cur) => pre + cur);
                        return sum / diffs.length;
                    };

                    // 颜色混合
                    // 参考 https://stackoverflow.com/questions/12011081/alpha-blending-2-rgba-colors-in-c
                    const mixColor = (backRgba, fr