/// <summary>
/// given a location of a pixel (x,y), returns the info about that pixel.
/// </summary>
/// <param name="i"></param>
/// <param name="j"></param>
/// <param name="imageDataArray"></param>
/// <param name="injectedContext"></param>
/// <returns></returns>
public pixel getPixelInfo(int i, int j, byte[] imageDataArray, SeamCarvingContext injectedContext)
{
byte[] red = { 0, 0, 0, this.getPixel(imageDataArray, i, j, 0, injectedContext) };
byte[] green = { 0, 0, 0, this.getPixel(imageDataArray, i, j, 1, injectedContext) };
byte[] blue = { 0, 0, 0, this.getPixel(imageDataArray, i, j, 2, injectedContext) };
byte[] alpha = { 0, 0, 0, this.getPixel(imageDataArray, i, j, 3, injectedContext) };
if (BitConverter.IsLittleEndian)
{
Array.Reverse(red);
Array.Reverse(green);
Array.Reverse(blue);
Array.Reverse(alpha);
}
int redInt = BitConverter.ToInt32(red, 0);
int greenInt = BitConverter.ToInt32(green, 0);
int blueInt = BitConverter.ToInt32(blue, 0);
int alphaInt = BitConverter.ToInt32(alpha, 0);
pixel toReturn = new pixel();
toReturn.red = redInt;
toReturn.green = greenInt;
toReturn.blue = blueInt;
toReturn.alpha = alphaInt;
return toReturn;
}
/// <summary>
/// given a seam carving context, calculates the gradient of every pixel.
/// </summary>
/// <param name="injectedContext"></param>
public void calculateGradient(SeamCarvingContext injectedContext)
{
injectedContext.gradientArray = new byte[injectedContext.imageDataArray.Length];
for (int i = 1; i < injectedContext.Height - 1; i++)
{
for (int j = 1; j < injectedContext.Width - 1; j++)
{
pixel last = seamUtilities.getPixelInfo(i, j - 1, injectedContext.imageDataArray, injectedContext);
pixel current = seamUtilities.getPixelInfo(i, j, injectedContext.imageDataArray, injectedContext);
pixel next = seamUtilities.getPixelInfo(i, j + 1, injectedContext.imageDataArray, injectedContext);
byte gradient = calculateGradientOfPixel(last, current, next);
seamUtilities.setPixel(injectedContext.gradientArray, i, j, 0, gradient, injectedContext);
seamUtilities.setPixel(injectedContext.gradientArray, i, j, 1, gradient, injectedContext);
seamUtilities.setPixel(injectedContext.gradientArray, i, j, 2, gradient, injectedContext);
seamUtilities.setPixel(injectedContext.gradientArray, i, j, 3, 0xff, injectedContext);
}
}
}
/// <summary>
/// takes three pixels and calculates the current pixels difference from the pixels next to it.
/// </summary>
/// <param name="last"></param>
/// <param name="current"></param>
/// <param name="next"></param>
/// <returns></returns>
public byte calculateGradientOfPixel(pixel last, pixel current, pixel next)
{
return((byte)((((current.red - next.red + 1) * (current.blue - next.blue + 1) * (current.green - next.green + 1)) + last.red) / 128));
}