/// <summary>
/// Visualizes a few examples and their classification outcome to get an overall impression of the network's accuracy.
/// </summary>
/// <param name="network">The neural network to test.</param>
/// <param name="characterSource">The character source to generate samples from.</param>
/// <param name="rows">Amount of examples to show vertically.</param>
/// <param name="columns">Amount of examples to show horizontally.</param>
/// <returns>An object that can be assigned directly to an ImageControl's Source property.</returns>
public static ImageSource DrawTestGallery(IOCRModel ocrModel, ICharacterSource characterSource, int rows, int columns)
{
const int inputScaleFact = 2;
const int labelHeight = 16;
int width = (characterSource.ImageWidth * inputScaleFact + sectionPadding) * columns;
int height = (characterSource.ImageHeight * inputScaleFact + labelHeight + sectionPadding) * rows;
var output = new WriteableBitmap(width, height, 96.0, 96.0, PixelFormats.Rgb24, null);
byte[] bytes = new byte[width * height * 3];
var samples = characterSource.GenerateMulti(rows * columns);
int baseY = 0;
for (int i = 0; i < rows; i++)
{
int baseX = 0;
for (int j = 0; j < columns; j++)
{
var sample = samples[i * columns + j];
drawInput(sample.Image, bytes, inputScaleFact, baseX, baseY, width);
var result = ocrModel.ExecuteSingle(sample.Image);
bool correct = (result.MostConfident == sample.Character);
for (int y = baseY + characterSource.ImageHeight * inputScaleFact + labelHeight / 4;
y < baseY + characterSource.ImageHeight * inputScaleFact + labelHeight / 2; y++)
{
for (int x = baseX; x < baseX + characterSource.ImageWidth * inputScaleFact; x++)
{
bytes[(x + y * width) * 3] = (byte)(correct ? 0 : 255);
bytes[(x + y * width) * 3 + 1] = (byte)(correct ? 255 : 0);
bytes[(x + y * width) * 3 + 2] = (byte)0;
}
}
baseX += characterSource.ImageWidth * inputScaleFact + sectionPadding;
}
baseY += characterSource.ImageHeight * inputScaleFact + labelHeight + sectionPadding;
}
output.WritePixels(new Int32Rect(0, 0, width, height), bytes, width * 3, 0);
return(output);
}
