How to load an RGB image from the resource folder into an int/float[] containing only grayscale values?

Questions & Answers
1

what I’ve been able to do so far is to read an image as a texture2D using Resources.loadAll(“”)
and then iterate through the image using nested for loop and get each individual pixel stored into a float
I have the ability to access the the red, blue , green, alpha and even grayscale values individually but what I need to store the the black and white representation of the image that is merge the 3 layers of RBG into a single layer and get the grayscale values either 1 or 0 , how can I do that?

Texture2D[] images = Resources.LoadAll<Texture2D> ("");
		float[] finalImage = new float[ images[0].width * images[0].height ];
		int index = 0;
		for (int i = 0; i < images [0].width; i++) {
		
		
			for (int j = 0; j < images [0].height; j++) {
			

				finalImage[index]=	Mathf.Round(images [0].GetPixel (i, j).a);
				if (finalImage[index] ==0 && index<100) {
					Debug.Log (i + " " + j);
				}
				index++;
			}
		}
2

You can use a shader

Shader "Loreal/GeyScale"
{
	Properties
	{
		_MainTex("MainTex", 2D) = "white" {}
	}

	SubShader
	{
		// No culling or depth
		Cull Off ZWrite Off ZTest Always

		Blend SrcAlpha OneMinusSrcAlpha
		Tags{ "Queue" = "Transparent" }

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert(appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}
			sampler2D _MainTex;
			

			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 color = tex2D(_MainTex, i.uv);
				
			
			float greyscaleAverage = (color.r + color.g + color.b) / 3.0f;

				return greyscaleAverage;
			}
			ENDCG
		}
	}
}

Then “all you need to do” is to blit that render texture to your texture2d

RenderTexture rt = RenderTexture.GetTemporary(textureRGB.width, textureRGB.height));

Graphics.Blit(textureRGB rt, grayScaleMaterial);

textureA.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0, false);

// not used textureA.Apply();

Then you can use textureA.GetRawTextureData() to have an array of color and keep only the r/g/b or a of your texture…

Not sure this is the fasted way