private void TestImage(IEnumerable <Point> arrayOfTestPoints)
{
if (_trace)
{
string imageType;
if (_sourceImageType == ImageTypes.Mono16)
{
imageType = "Mono16";
}
else if (_sourceImageType == ImageTypes.Mono8)
{
imageType = "Mono8";
}
else if (_sourceImageType == ImageTypes.Mono8Signed)
{
imageType = "Mono8Signed";
}
else if (_sourceImageType == ImageTypes.Mono16Signed)
{
imageType = "Mono16Signed";
}
else
{
imageType = "Rgb";
}
TraceLine("");
TraceLine(imageType);
TraceLine(String.Format("Scale (Fit/Scale): {0}/{1}", _scaleToFit, _scale));
TraceLine(String.Format("Orientation(FH/FV/R): {0}/{1}/{2}", _flipHorizontal, _flipVertical, _rotation));
TraceLine(String.Format("Translation: {0}, {1}", _translationX, _translationY));
}
CreateImageLayer(_sourceImageType);
CreatePhantom();
//render the image to a bitmap
Bitmap dstBitmap = ImageRendererTestUtilities.RenderLayer(_image, _dstWidth, _dstHeight);
if (_traceBitmap)
{
string strTraceBitmap = "Bitmap:\n";
for (int y = 0; y < dstBitmap.Height; y++)
{
for (int x = 0; x < dstBitmap.Width; x++)
{
byte pixelValue = dstBitmap.GetPixel(x, y).R;
strTraceBitmap += String.Format("{0} ", (int)pixelValue);
}
strTraceBitmap += "\n";
}
TraceLine(strTraceBitmap);
}
foreach (Point dstPoint in arrayOfTestPoints)
{
// //The point of the unit test here is to do the same bilinear calculation as is done in the
// //actual interpolation code, but in a more reliable & simpler way (e.g. not using pointer
// //arithmetic, offsets, rectangles, etc).
Rectangle dstViewableRectangle;
RectangleF srcViewableRectangle;
ImageRenderer.CalculateVisibleRectangles(_image, new Rectangle(0, 0, _dstWidth, _dstHeight), out dstViewableRectangle, out srcViewableRectangle);
byte dstValue = dstBitmap.GetPixel(dstPoint.X, dstPoint.Y).R; //just check the value of R.
if (dstViewableRectangle.Contains(dstPoint))
{
PointF dstTestPoint = new PointF(dstPoint.X + 0.5F, dstPoint.Y + 0.5F);
PointF srcTestPoint = _image.SpatialTransform.ConvertToSource(dstTestPoint);
float tolerance = 1 / (8F * _fixedScale);
// We can take advantage of the fact that we are using fixed point arithmetic to do the interpolation
// because it essentially means that there is a discrete set of resulting values for a given 4-pixel
// region (dx,dy between 0.0 -> 1.0 translates to 0/128 -> 128/128 in fixed point).
// Because we use the SpatialTransform class to calculate the source coordinate in the C# world,
// and 2 rectangles in the C++ world, we can't expect to get *exactly* the same answer in both cases.
// Therefore, we calculate the values at source points offset by a tolerance much smaller than 1/128,
// so that if by chance the source coordinates are teetering on a fixed-point boundary (e.g. slight
// changes would result in dx or dy being off by +-1/128) then we can still be confident that the
// source coordinates the interpolator is calculating are reasonable, and thus the interpolated value
// is correct, even if it's not exactly what we calculate in C# with zero-tolerance.
// The tolerance used here is 1/(8*128) ~= 0.001. When the test passes, this means that the C# and
// C++ calculations of the source pixel coordinate (and thus, dx/dy and the interpolated value) agree to
// within one one-thousandth of a pixel.
List <SizeF> offsets = new List <SizeF>();
offsets.Add(new SizeF(0F, 0F));
offsets.Add(new SizeF(-tolerance, -tolerance));
offsets.Add(new SizeF(-tolerance, +tolerance));
offsets.Add(new SizeF(+tolerance, -tolerance));
offsets.Add(new SizeF(+tolerance, +tolerance));
bool success = false;
int i = 0;
foreach (SizeF offset in offsets)
{
PointF srcPoint00 = PointF.Add(srcTestPoint, offset);
byte backCalculateValue = PerformBilinearInterpolationAt(srcPoint00);
if (_trace)
{
string strMessage = String.Format("Test Point #{0} ({1}, {2}): {3}, BackCalculated({4:F16}, {5:F16}): {6}\n",
++i, dstTestPoint.X, dstTestPoint.Y, dstValue, srcPoint00.X, srcPoint00.Y,
backCalculateValue);
TraceLine(strMessage);
}
if (backCalculateValue == dstValue)
{
success = true;
break;
}
}
Assert.IsTrue(success, "Failed for all test points within tolerance range.");
}
else
{
//The bilinear interpolation algorithm should not calculate any values outside the dstViewableRectangle.
string strMessage = String.Format("Point outside rectangle ({0}, {1}) = {2}", dstPoint.X, dstPoint.Y, dstValue);
if (_trace)
{
TraceLine(strMessage);
}
Assert.AreEqual(0, dstValue, strMessage);
}
}
}
