Brightness script makes image completely black and white

Questions & Answers
1

I want to change the brightness of the image I uploaded in my unity scene. Here’s my current script:

public void AdjustBrightness(string brightness)
    {
        int brightnessInt = Convert.ToInt32(brightness);
        int mappedBrightness = (51 * brightnessInt) / 10 - 255;
        //Make an empty Texture the same same as the original 
        Texture2D bitmapImage = new Texture2D(imgTexture.width, imgTexture.height);

        if (mappedBrightness < -255) mappedBrightness = -255;
        if (mappedBrightness > 255) mappedBrightness = 255;
        Color color;
        for (int i = 0; i < bitmapImage.width; i++)
        {
            for (int j = 0; j < bitmapImage.height; j++)
            {
                color = bitmapImage.GetPixel(i, j);
                int cR = (int)color.r + mappedBrightness;
                int cG = (int)color.g + mappedBrightness;
                int cB = (int)color.b + mappedBrightness;

                if (cR < 0) cR = 0;
                if (cR > 255) cR = 255;

                if (cG < 0) cG = 0;
                if (cG > 255) cG = 255;

                if (cB < 0) cB = 0;
                if (cB > 255) cB = 255;

                bitmapImage.SetPixel(i, j,
    new Color((float)cR, (float)cG, (float)cB));
            }
        }
            //Apply all SetPixel changes
            bitmapImage.Apply();

            //Connect texture to material of GameObject this script is attached to 
            Image.renderer.material.mainTexture = bitmapImage as Texture;
    }

For some reason, this script completely changes my image to black. Then if I increase my values to a certain point, the image turns fully white.

Am I calculating brightness correctly here?

Btw, in the beginning I am mapping the brightness value from my current input range of values between 0% to 100% to -255 to 255 to use this script. Is this fine? That is, there is an input field to enter a brightness value of 0 to 100 and to use this formula, I have to map the value of 50% to what 50% means on the scale/range of -255 to 255 right?

2

Each component in Color is assumed to be a float between 0 to 1. This is unlike Color32 where each color component is a byte value from 0 to 255. So change line 30 to

new Color32((byte) cR, (byte) cG, (byte) cB));

or

new Color(cR/255f, cG/255f, cB/255f));