Need help making Rainbow effect code not dependent on frames

Questions & Answers
1

Hello I have a script that changes the color of an image over time. but i have to use the fixed update function for it to work properly i tried using a while loop but kept crashing the program when i used it. i would like to get the script to not be reliant on the fixed update function and would like to use a speed variable to affect the speed of the color transition for the rainbow effect but i am unsure how. here is the script below

public class ColorText : MonoBehaviour
{
    [SerializeField]
    private TextMeshProUGUI test;
    public GameObject Panel;
    public Image image;

    public bool loop = false;
    public int loopIndex = 0;
    public Color[] characterColors =
    {
        //standard colors
    new Color(0,0,0,0), //clear
    new Color(0,0,0,1), //black
    new Color(0,0,1,1), //blue
    new Color(0,1,1,1), //cyan
    new Color(0.5f,0.5f,0.5f,1), //gray
    new Color(0,1,0,1), //green
    new Color(1,0,1,1), //magenta
    new Color(1,0,0,1), //red
    new Color(1,1,1,1), //white
    new Color(1,0.92f,0.016f,1), //yellow

        //custom colors
        //new Color(0,0,0,1), //color name
    };

    // Start is called before the first frame update
    void Start()
    {
        image = GameObject.Find("Root").GetComponent<Image>();
    }

    // Update is called once per frame
    void FixedUpdate()
    {
        Color();
    }

    private void Update()
    {
        if (Input.GetButtonDown("DownArrow"))
            loop = true;
        if (Input.GetButtonDown("UpArrow"))
            loop = false;
    }

    void Color()
    {
        image.color = characterColors[loopIndex];

        if(loopIndex >= characterColors.Length - 1 && loop)
        {
            loopIndex = 1;
        }

        if (loopIndex < characterColors.Length && loop)
        {
            loopIndex++;
        }
        
    }


}
2