Alpha blend, gray scale and sepia

PixelManipulation.cs

        public Texture2D ToGrayScale(Color[] cArr)
        {
            var bottomPixelData = cArr;
            int count = bottomPixelData.Length;
            var resultData = new Color[count];
            for(int i = 0; i < count; i++)
            {
                Color bottomPixels = bottomPixelData[i];
                Color temp = new Color(
                    (1f-bottomPixels.r),
                    (1f-bottomPixels.g),
                    (1f-bottomPixels.b),
                    (1f-bottomPixels.a));
                resultData[i] = bottomPixels * temp.grayscale
                                             * bottomPixels.linear
                                             * bottomPixels.linear
                                             * bottomPixels.linear;
            }
            var res = new Texture2D(1280, 720);
            res.SetPixels(resultData);
            res.Apply();
            return res;
        }
        
        public Texture2D ToSepia(Color[] cArr)
        {
            var bottomPixelData = cArr;
            int count = bottomPixelData.Length;
            var resultData = new Color[count];
            for(int i = 0; i < count; i++)
            {
                Color bottomPixels = bottomPixelData[i];
                float outputRed = (bottomPixels.r * 0.393f) + (bottomPixels.g * .769f) + (bottomPixels.b * .189f);
                float outputGreen = (bottomPixels.r * .349f) + (bottomPixels.g * .686f) + (bottomPixels.b * .168f);
                float outputBlue = (bottomPixels.r * .272f) + (bottomPixels.g * .534f) + (bottomPixels.b * .131f);
                Color temp = new Color(
                    (outputRed),
                    (outputGreen),
                    (outputBlue),
                    (1f));

                resultData[i] = temp;
            }
            var res = new Texture2D(1280, 720);
            res.SetPixels(resultData);
            res.Apply();
            return res;
        }
        
        public Texture2D AlphaBlend(Texture2D textureBottom, Texture2D textureTop)
        {
            if (textureBottom.width != textureTop.width || textureBottom.height != textureTop.height)
                throw new System.InvalidOperationException("AlphaBlend only works with two equal sized images");
            var bottomPixelData = textureBottom.GetPixels();
            var topPixelData = textureTop.GetPixels();
            int count = bottomPixelData.Length;
            var resultData = new Color[count];
            for(int i = 0; i < count; i++)
            {
                Color bottomPixels = bottomPixelData[i];
                Color topPixels = topPixelData[i];

                float srcF = topPixels.a;
                float destF = 1f - topPixels.a;
                float alpha = srcF + destF * bottomPixels.a;
                Color resultColor = (topPixels * srcF + bottomPixels * bottomPixels.a * destF)/alpha;
                resultColor.a = alpha;
                resultData[i] = resultColor;
            }
            var res = new Texture2D(textureBottom.width, textureBottom.height);
            res.SetPixels(resultData);
            res.Apply();
            return res;
        }