Bitmap matrix from Texture2D

Unity Engine
1

Hi I’m trying to convert c# code that works with System.Drawing.Bitmap into Unity. What I’m trying to do is swap out all references to Bitmap with Texture2D.

I have the following method:

/// <summary>
        ///
        /// Produces a binary Matrix with Dimensions
        /// For the threshold, we take the sum of  weighted R,g,b value. The sum of weights must be 1.
        /// The result fills the field bm;
        /// </summary>
        /// <param name="bitmap"> A Bitmap, which will be transformed to a binary Matrix</param>
        /// <returns>Returns a binaray boolean Matrix </returns>
        static Bitmap_p ConvertBitmap(Bitmap bitmap)
        {

            byte[] Result = new byte[bitmap.Width * bitmap.Height];
            BitmapData SourceData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
            unsafe
            {
                byte* SourcePtr = (byte*)(void*)SourceData.Scan0;

                int l = Result.Length;
                Debug.Log(l);
                for (int i = 0; i < l; i++)
                {
                    //  if ((0.2126 * (double)SourcePtr[4 * i + 2] + 0.7153 * (double)SourcePtr[4 * i + 1] + 0.0721 * (double)SourcePtr[4 * i]) < Treshold*255)
                    if (((double)SourcePtr[4 * i + 2] + (double)SourcePtr[4 * i + 1] + (double)SourcePtr[4 * i]) < Treshold * 255 * 3)
                        Result[i] = 1;
                    else
                        Result[i] = 0;
                }
            }

            bitmap.UnlockBits(SourceData);
            bm = new Bitmap_p(bitmap.Width, bitmap.Height);
            bm.data = Result;

            return bm;
        }
        }

I tried to do this:

        static Bitmap_p ConvertBitmap(Texture2D texture)
        {

            byte[] original = texture.EncodeToPNG();
            byte[] result = new byte[texture.width * texture.height];

            for (int i = 0; i < original.Length; i++)
            {
                if (((double)original[4 * i + 2] + (double)original[4 * i + 1] + (double)original[4 * i]) < Treshold * 255 * 3)
                    result[i] = 1;
                else
                    result[i] = 0;
            }

            bm = new Bitmap_p(texture.width, texture.height);
            bm.data = result;

            return bm;
        }

but I’m getting array index out of bounds errors. I’m completely not used to working with pointers so I’m confused as heck. Also, perhaps PixelFormat.Format32bppArgb is a different format than EncodeToPNG? Can anyone help me along?

2 Likes
2

Got it.

      static Bitmap_p ConvertTexture(Texture2D texture)
        {
            var original = texture.GetPixels32();
            byte[] result = new byte[texture.width * texture.height];

            for (int i = 0; i < original.Length; i++)
            {
                if(original[i].r + original[i].g + original[i].b < Treshold * 255 * 3)
                {
                    result[i] = 1;
                }
                else
                {
                    result[i] = 0;
                }
            }

            bm = new Bitmap_p(texture.width, texture.height){
                data = result
            };

            return bm;
        }

Leaving this thread as it might be useful to others.

7 Likes