/// <summary>
///
/// </summary>
/// <param name="location"></param>
/// <returns></returns>
public static sbyte[] Altitude(string location)
{
sbyte[] array;
using (var bitmap = new Bitmap(location))
{
array = new sbyte[bitmap.Width * bitmap.Height];
array.Initialize();
// Lock the bitmap's bits.
var rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
//lock the bitmap bits
BitmapData bmpData;
bmpData = bitmap.LockBits(rect, ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
// Get the address of the first line.
var ptr = bmpData.Scan0;
// Declare an array to hold the bytes of the bitmap.
var bytes = bmpData.Stride * bitmap.Height;
var rgbValues = new byte[bytes];
// Copy the RGB values into the array.
Marshal.Copy(ptr, rgbValues, 0, bytes);
var stride = bmpData.Stride;
for (var coulmn = bmpData.Height - 1; coulmn >= 0; coulmn--)
{
for (var row = 0; row < bmpData.Width; row++)
{
var red = rgbValues[(coulmn * stride) + (row * 3) + 2];
var green = rgbValues[(coulmn * stride) + (row * 3) + 1];
var blue = rgbValues[(coulmn * stride) + (row * 3)];
if (red == green && red == blue)
{
var partialresult = red - 128;
if (partialresult > sbyte.MaxValue)
{
partialresult = sbyte.MaxValue;
}
if (partialresult < sbyte.MinValue)
{
partialresult = sbyte.MinValue;
}
array[(coulmn * (bmpData.Width)) + row] = (sbyte)partialresult;
continue;
}
if (red == blue && green == 0)
{
var partialresult = red - 128;
if (partialresult > sbyte.MaxValue)
{
partialresult = sbyte.MaxValue;
}
if (partialresult < sbyte.MinValue)
{
partialresult = sbyte.MinValue;
}
array[(coulmn * (bmpData.Width)) + row] = (sbyte)partialresult;
continue;
}
if (green > 0 && blue == 0 && red == 0)
{
var partialresult = green - 128;
if (partialresult > sbyte.MaxValue)
{
partialresult = sbyte.MaxValue;
}
if (partialresult < sbyte.MinValue)
{
partialresult = sbyte.MinValue;
}
array[(coulmn * (bmpData.Width)) + row] = (sbyte)partialresult;
continue;
}
if (blue > 0 && red == 0 && green == 0)
{
var partialresult = blue - 128;
if (partialresult > sbyte.MaxValue)
{
partialresult = sbyte.MaxValue;
}
if (partialresult < sbyte.MinValue)
{
partialresult = sbyte.MinValue;
}
array[(coulmn * (bmpData.Width)) + row] = (sbyte)partialresult;
continue;
}
array[(coulmn * (bmpData.Width)) + row] = 0;
}
}
}
return(array);
}