/// <summary>
/// renders the ssim structure into a texture
/// </summary>
public void GetStructureTexture(ITexture image1, ITexture image2, ITexture dst, Settings s)
{
Debug.Assert(image1.HasSameDimensions(image2));
Debug.Assert(image1.HasSameDimensions(dst));
var cache = GetCache(image1);
var structTex = cache.GetTexture();
using (var data = new ImagesCorrelationStats(cache))
{
foreach (var lm in image1.LayerMipmap.Range)
{
RenderImagesCorrelation(image1, image2, data, lm);
RenderStructure(data, structTex, lm);
if (!s.Multiscale)
{
RenderRedToRgba(structTex, dst, lm);
}
}
if (s.Multiscale)
{
foreach (var lm in image1.LayerMipmap.Range)
{
RenderContrastStructureMultiscale(structTex, lm);
RenderRedToRgba(structTex, dst, lm);
}
}
}
cache.StoreTexture(structTex);
}
private void RenderContrast(ImagesCorrelationStats src, ITexture dst, LayerMipmapSlice lm)
{
contrastShader.Run(new []
{
src.Image1.Variance,
src.Image2.Variance
}, dst, lm, models.SharedModel.Upload);
}
private void RenderLuminance(ImagesCorrelationStats src, ITexture dst, LayerMipmapSlice lm)
{
luminanceShader.Run(new []
{
src.Image1.Expected,
src.Image2.Expected
}, dst, lm, models.SharedModel.Upload);
}
private void RenderStructure(ImagesCorrelationStats src, ITexture dst, LayerMipmapSlice lm)
{
structureShader.Run(new []
{
src.Image1.Variance,
src.Image2.Variance,
src.Correlation
}, dst, lm, models.SharedModel.Upload);
}
private void RenderImagesCorrelation(ITexture src1, ITexture src2, ImagesCorrelationStats dst,
LayerMipmapSlice lm)
{
// calc expected value and variance
RenderImageVariance(src1, dst.Image1, lm);
RenderImageVariance(src2, dst.Image2, lm);
// calc correlation coefficient
var lumaMult = dst.Cache.GetTexture();
multiplyShader.Run(new [] { dst.Image1.Luma, dst.Image2.Luma }, lumaMult, lm, models.SharedModel.Upload);
// blur result
var lumaBlur = dst.Cache.GetTexture();
gaussShader.Run(lumaMult, lumaBlur, lm, models.SharedModel.Upload, dst.Cache);
// calc correlation with blurred(luma1*luma2) - mu1*mu2
subtractProductShader.Run(new [] { lumaBlur, dst.Image1.Expected, dst.Image2.Expected }, dst.Correlation, lm, models.SharedModel.Upload);
dst.Cache.StoreTexture(lumaMult);
dst.Cache.StoreTexture(lumaBlur);
}
private void RenderSSIM(ImagesCorrelationStats src, ITexture dst, LayerMipmapSlice lm)
{
ssimShader2.Run(new [] { src.Image1.Expected, src.Image2.Expected, src.Image1.Variance, src.Image2.Variance, src.Correlation }, dst, lm, models.SharedModel.Upload);
}
public Stats GetStats(ITexture image1, ITexture image2, LayerMipmapRange lmRange, Settings s)
{
Debug.Assert(image1.HasSameDimensions(image2));
Debug.Assert(lmRange.IsSingleMipmap);
var cache = GetCache(image1);
var lumTex = cache.GetTexture();
var contTex = cache.GetTexture();
var strucTex = cache.GetTexture();
var ssimTex = cache.GetTexture();
using (var data = new ImagesCorrelationStats(cache))
{
if (!s.Multiscale)
{
foreach (var lm in image1.LayerMipmap.RangeOf(lmRange))
{
// determine expected value, variance, correlation
RenderImagesCorrelation(image1, image2, data, lm);
// calc the three components
RenderLuminance(data, lumTex, lm);
RenderContrast(data, contTex, lm);
RenderStructure(data, strucTex, lm);
// build ssim
//RenderSSIM(data, ssimTex, lm);
RenderSSIM(lumTex, strucTex, contTex, ssimTex, lm);
}
}
else // multiscale
{
int endMipmap = Math.Min(lmRange.Mipmap + 5, image1.NumMipmaps);
for (int curMip = lmRange.Mipmap; curMip < endMipmap; ++curMip)
{
foreach (var lm in image1.LayerMipmap.RangeOf(new LayerMipmapRange(lmRange.Layer, curMip)))
{
// determine expected value, variance, correlation
RenderImagesCorrelation(image1, image2, data, lm);
// calc components
if (curMip == endMipmap - 1) // luminance only for last mipmap
{
RenderLuminance(data, lumTex, lm);
}
RenderContrast(data, contTex, lm);
RenderStructure(data, strucTex, lm);
}
}
// combine values of different scales to compute ssim
foreach (var lm in image1.LayerMipmap.RangeOf(lmRange))
{
// determine appropriate scale scores
RenderLuminanceMultiscale(lumTex, lm);
RenderContrastStructureMultiscale(contTex, lm);
RenderContrastStructureMultiscale(strucTex, lm);
// build ssim
RenderSSIM(lumTex, strucTex, contTex, ssimTex, lm);
}
}
}
var stats = new Stats
{
Luminance = GetAveragedValue(lumTex, lmRange, s.ExcludeBorders),
Contrast = GetAveragedValue(contTex, lmRange, s.ExcludeBorders),
Structure = GetAveragedValue(strucTex, lmRange, s.ExcludeBorders),
SSIM = GetAveragedValue(ssimTex, lmRange, s.ExcludeBorders)
};
cache.StoreTexture(lumTex);
cache.StoreTexture(contTex);
cache.StoreTexture(strucTex);
cache.StoreTexture(ssimTex);
return(stats);
}