Fast way to read png as int[]

I'm looking for the fastest way to treat a png file as an array of Int32 instead of Color32. The array is to be looped over only once and contains > 30 millions elements.

Code (CSharp):

1. int[] intmapArray = Resources.Load<Texture2D>("colormap").GetRawTextureData<int>().ToArray();
2.  
3. Color32 IntToColor(int colInt) => new((byte)colInt, (byte)(colInt >> 8), (byte)(colInt >> 16), (byte)(colInt >> 24))

Currently I'm using I'm using GetRawTextureData<int>() to get a NativeArray and then convert it to an int[] which is much faster than any byte[] or Color32[] alternative I've tried.

But slower than if I can get the BinaryFormatter to treat the png directly as an int[], or some equally-efficient method. Thanks in advance!

 

I wonder if there's some kind of tricks you could with the GCHandle stuff... like pinning it and pointing at it with a System.IntPtr, then shovel it back into an int[] array?

https://docs.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.gchandle?view=net-6.0

Not sure of the performance of all of that though.

I did use an OpenCV package off the asset store back in 2014 but it was a for-pay assset and I don't have access to it anymore anyway. Its generic type was what they called a

Mat

, basically an any-shaped vector, and they had rapid ways of getting Textures in and out of Mats.