Bugfixing: soft mask

Pdf4QtLib/sources/pdfblendfunction.cpp

@@ -519,7 +519,8 @@ PDFColorComponent PDFBlendFunction::getLuminosity(PDFRGB rgb)
 
 PDFColorComponent PDFBlendFunction::getLuminosity(PDFCMYK cmyk)
 {
-    return nonseparable_Lum(nonseparable_cmyk2rgb(cmyk));
+    // This is according to chapter 11.5.3, deriving soft mask from a group luminosity
+    return 1.0f - qMin(1.0f, 0.30f * cmyk[0] + 0.59f * cmyk[1] + 0.11f * cmyk[2] + cmyk[3]);
 }
 
 PDFRGB PDFBlendFunction::nonseparable_gray2rgb(PDFGray gray)

Pdf4QtLib/sources/pdftransparencyrenderer.cpp

@@ -168,6 +168,28 @@ void PDFFloatBitmap::setColorActivity(uint32_t mask)
     std::fill(m_activeColorMask.begin(), m_activeColorMask.end(), mask);
 }
 
+QImage PDFFloatBitmap::getChannelImage(uint8_t channelIndex) const
+{
+    if (channelIndex >= getPixelSize())
+    {
+        return QImage();
+    }
+
+    QImage image(int(getWidth()), int(getHeight()), QImage::Format_Grayscale8);
+
+    for (int y = 0; y < image.height(); ++y)
+    {
+        uchar* line = image.scanLine(y);
+        for (int x = 0; x < image.width(); ++x)
+        {
+            PDFConstColorBuffer buffer = getPixel(x, y);
+            line[x] = qRound(buffer[channelIndex] * 255);
+        }
+    }
+
+    return image;
+}
+
 PDFFloatBitmap PDFFloatBitmap::extractProcessColors() const
 {
     PDFPixelFormat format = PDFPixelFormat::createFormat(m_format.getProcessColorChannelCount(), 0, false, m_format.hasProcessColorsSubtractive(), false);

Pdf4QtLib/sources/pdftransparencyrenderer.h

@@ -220,6 +220,11 @@ public:
     /// \param mask Color activity
     void setColorActivity(uint32_t mask);
 
+    /// Returns gray image created from color channel. If color channel
+    /// is invalid, then empty image is returned.
+    /// \param channelIndex Channel index
+    QImage getChannelImage(uint8_t channelIndex) const;
+
     /// Extract process colors into another bitmap
     PDFFloatBitmap extractProcessColors() const;