Details lost when lightening or brightening an image

[Sempervivum]

When I used the function lighten() or brighten() I encountered the issue that details get lost in bright regions of an image. These areas simply grow white.
I coded another algorithms for brightening and it works much better: No details lost in bright regions.

    function brighten2(color, amount) {
        function helper(val, amount) {
            const delta = 255 - val,
                newVal = val + delta * amount / 100;
            return newVal;
        }
        amount = (amount === 0) ? 0 : (amount || 10);
        var rgb = tinycolor(color).toRgb();
        rgb.r = helper(rgb.r, amount);
        rgb.g = helper(rgb.g, amount);
        rgb.b = helper(rgb.b, amount);
        return tinycolor(rgb);
    }