Texture2D.GetPixels32
GetPixels32(miplevel: int = 0): Color32[];
Color32[] GetPixels32(int miplevel = 0);
def GetPixels32(miplevel as int = 0) as Color32[]
Description

Get a block of pixel colors in Color32 format.

This function returns an array of pixel colors of the whole mip level of the texture.

The returned array is a flattened 2D array, where pixels are laid out left to right, bottom to top (i.e. row after row). Array size is width by height of the mip level used. The default mip level is zero (the base texture) in which case the size is just the size of the texture. In general case, mip level size is mipWidth=max(1,width>>miplevel) and similarly for height.

The texture must have the Read/Write Enabled flag set in the import settings, otherwise this function will fail.

Using GetPixels32 can be faster than calling GetPixel repeatedly, especially for large textures. In addition, GetPixels32 can access individual mipmap levels.
	// Rotate an image 180 degrees by reversing the order
	// of the pixels.
	
	// Source texture.
	var sourceTex: Texture2D;	
	
	
	function Start () {
		// Get the pixel block and reverse the array to
		// rotate the image.
		var pix = sourceTex.GetPixels32();
		System.Array.Reverse(pix);
		
		// Copy the reversed image data to a new texture.
		var destTex = new Texture2D(sourceTex.width, sourceTex.height);
		destTex.SetPixels32(pix);
		destTex.Apply();
		
		// Set the current object's texture to show the
		// rotated image.
		renderer.material.mainTexture = destTex;
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public Texture2D sourceTex;
    void Start() {
        Color32[] pix = sourceTex.GetPixels32();
        System.Array.Reverse(pix);
        Texture2D destTex = new Texture2D(sourceTex.width, sourceTex.height);
        destTex.SetPixels32(pix);
        destTex.Apply();
        renderer.material.mainTexture = destTex;
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public sourceTex as Texture2D

	def Start() as void:
		pix as (Color32) = sourceTex.GetPixels32()
		System.Array.Reverse(pix)
		destTex as Texture2D = Texture2D(sourceTex.width, sourceTex.height)
		destTex.SetPixels32(pix)
		destTex.Apply()
		renderer.material.mainTexture = destTex