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Overprint

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This commit is contained in:
Jakub Melka
2021-01-24 18:41:17 +01:00
parent 443c656a46
commit 77255cc56a
5 changed files with 173 additions and 44 deletions
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15
Pdf4QtLib/sources/pdfblendfunction.cpp
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@ -97,6 +97,8 @@ bool PDFBlendModeInfo::isSeparable(BlendMode mode)
case BlendMode::Difference:
case BlendMode::Exclusion:
case BlendMode::Compatible:
case BlendMode::Overprint_SelectBackdrop:
case BlendMode::Overprint_SelectNonZeroSourceOrBackdrop:
return true;
case BlendMode::Hue:
@ -339,6 +341,19 @@ PDFColorComponent PDFBlendFunction::blend(BlendMode mode, PDFColorComponent Cb,
case BlendMode::Exclusion:
return Cb + Cs - 2.0f * Cb * Cs;
case BlendMode::Overprint_SelectBackdrop:
return Cb;
case BlendMode::Overprint_SelectNonZeroSourceOrBackdrop:
{
if (qFuzzyIsNull(Cs))
{
return Cb;
}
return Cs;
}
default:
{
Q_ASSERT(false);

4
Pdf4QtLib/sources/pdfblendfunction.h
View File

@ -51,6 +51,10 @@ enum class BlendMode
// to normal. It should be recognized for sake of compatibility.
Compatible, ///< Equals to normal
// Special blend modes for handling overprint. Used only internally.
Overprint_SelectBackdrop,
Overprint_SelectNonZeroSourceOrBackdrop,
// Invalid blending mode - for internal purposes only
Invalid
};

1
Pdf4QtLib/sources/pdfcolorspaces.h
View File

@ -44,6 +44,7 @@ class PDFRenderErrorReporter;
using PDFColor = PDFFlatArray<PDFColorComponent, 4>;
using PDFColorSpacePointer = QSharedPointer<PDFAbstractColorSpace>;
using PDFColorBuffer = PDFBuffer<PDFColorComponent>;
using PDFConstColorBuffer = PDFBuffer<const PDFColorComponent>;
static constexpr const int COLOR_SPACE_MAX_LEVEL_OF_RECURSION = 12;

130
Pdf4QtLib/sources/pdftransparencyrenderer.cpp
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@ -47,6 +47,12 @@ PDFColorBuffer PDFFloatBitmap::getPixel(size_t x, size_t y)
return PDFColorBuffer(m_data.data() + index, m_pixelSize);
}
PDFConstColorBuffer PDFFloatBitmap::getPixel(size_t x, size_t y) const
{
const size_t index = getPixelIndex(x, y);
return PDFConstColorBuffer(m_data.data() + index, m_pixelSize);
}
PDFColorBuffer PDFFloatBitmap::getPixels()
{
return PDFColorBuffer(m_data.data(), m_data.size());
@ -130,7 +136,9 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
PDFFloatBitmap& softMask,
bool alphaIsShape,
PDFColorComponent constantAlpha,
BlendMode mode)
BlendMode mode,
uint32_t activeColorChannels,
OverprintMode overprintMode)
{
Q_ASSERT(source.getWidth() == target.getWidth());
Q_ASSERT(source.getHeight() == target.getHeight());
@ -146,16 +154,104 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
const uint8_t opacityChannel = pixelFormat.getOpacityChannelIndex();
const uint8_t colorChannelStart = pixelFormat.getColorChannelIndexStart();
const uint8_t colorChannelEnd = pixelFormat.getColorChannelIndexEnd();
const uint8_t processColorChannelStart = pixelFormat.getProcessColorChannelIndexStart();
const uint8_t processColorChannelEnd = pixelFormat.getProcessColorChannelIndexEnd();
const uint8_t spotColorChannelStart = pixelFormat.getSpotColorChannelIndexStart();
const uint8_t spotColorChannelEnd = pixelFormat.getSpotColorChannelIndexEnd();
std::vector<PDFColorComponent> B_i(source.getPixelSize(), 0.0f);
std::vector<BlendMode> channelBlendModes(source.getPixelSize(), mode);
// For blending spot colors, only white preserving blend modes are possible.
// If this is not the case, revert spot color blend mode to normal blending.
// See 11.7.4.2 of PDF 2.0 specification.
if (pixelFormat.hasSpotColors() && !PDFBlendModeInfo::isWhitePreserving(mode))
{
auto itBegin = std::next(channelBlendModes.begin(), spotColorChannelStart);
auto itEnd = std::next(channelBlendModes.begin(), spotColorChannelEnd);
std::fill(itBegin, itEnd, BlendMode::Normal);
}
// Handle overprint mode for normal blend mode. We do not support
// oveprinting for other blend modes, than normal.
switch (overprintMode)
{
case OverprintMode::NoOveprint:
break;
case OverprintMode::Overprint_Mode_0:
{
// Select source color, if channel is active,
// otherwise select backdrop color.
for (uint8_t colorChannelIndex = colorChannelStart; colorChannelIndex < colorChannelEnd; ++colorChannelIndex)
{
uint32_t flag = (static_cast<uint32_t>(1)) << colorChannelIndex;
if (channelBlendModes[colorChannelIndex] == BlendMode::Normal && !(activeColorChannels & flag))
{
// Color channel is inactive
channelBlendModes[colorChannelIndex] = BlendMode::Overprint_SelectBackdrop;
}
}
break;
}
case OverprintMode::Overprint_Mode_1:
{
// For process colors, select source color, if it is nonzero,
// otherwise select backdrop. If process color channel is inactive,
// select backdrop.
if (pixelFormat.hasProcessColors() && mode == BlendMode::Normal)
{
for (uint8_t colorChannelIndex = processColorChannelStart; colorChannelIndex < processColorChannelEnd; ++colorChannelIndex)
{
uint32_t flag = (static_cast<uint32_t>(1)) << colorChannelIndex;
if (!(activeColorChannels & flag))
{
// Color channel is inactive
channelBlendModes[colorChannelIndex] = BlendMode::Overprint_SelectBackdrop;
}
else
{
// Color channel is active, but select source color only, if it is nonzero
channelBlendModes[colorChannelIndex] = BlendMode::Overprint_SelectNonZeroSourceOrBackdrop;
}
}
}
if (pixelFormat.hasSpotColors())
{
// For spot colors, select backdrop, if channel is inactive,
// otherwise select source color.
for (uint8_t colorChannelIndex = spotColorChannelStart; colorChannelIndex < spotColorChannelEnd; ++colorChannelIndex)
{
uint32_t flag = (static_cast<uint32_t>(1)) << colorChannelIndex;
if (channelBlendModes[colorChannelIndex] == BlendMode::Normal && !(activeColorChannels & flag))
{
// Color channel is inactive
channelBlendModes[colorChannelIndex] = BlendMode::Overprint_SelectBackdrop;
}
}
}
break;
}
default:
{
Q_ASSERT(false);
break;
}
}
for (size_t x = 0; x < width; ++x)
{
for (size_t y = 0; y < height; ++y)
{
PDFColorBuffer sourceColor = source.getPixel(x, y);
PDFConstColorBuffer sourceColor = source.getPixel(x, y);
PDFColorBuffer targetColor = target.getPixel(x, y);
PDFColorBuffer backdropColor = backdrop.getPixel(x, y);
PDFColorBuffer initialBackdropColor = initialBackdrop.getPixel(x, y);
PDFConstColorBuffer backdropColor = backdrop.getPixel(x, y);
PDFConstColorBuffer initialBackdropColor = initialBackdrop.getPixel(x, y);
PDFColorBuffer alphaColorBuffer = softMask.getPixel(x, y);
const PDFColorComponent softMaskValue = alphaColorBuffer[0];
@ -199,40 +295,33 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
{
for (uint8_t i = pixelFormat.getProcessColorChannelIndexStart(); i < pixelFormat.getProcessColorChannelIndexEnd(); ++i)
{
B_i[i] = PDFBlendFunction::blend(mode, backdropColor[i], sourceColor[i]);
B_i[i] = PDFBlendFunction::blend(channelBlendModes[i], backdropColor[i], sourceColor[i]);
}
}
else
{
for (uint8_t i = pixelFormat.getProcessColorChannelIndexStart(); i < pixelFormat.getProcessColorChannelIndexEnd(); ++i)
{
B_i[i] = 1.0f - PDFBlendFunction::blend(mode, 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
B_i[i] = 1.0f - PDFBlendFunction::blend(channelBlendModes[i], 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
}
}
}
if (pixelFormat.hasSpotColors())
{
// Blend mode for spot colors must be white-preserving,
// see 11.7.4.2 of PDF 2.0 specification
BlendMode spotBlendMode = mode;
if (!PDFBlendModeInfo::isWhitePreserving(mode))
{
spotBlendMode = BlendMode::Normal;
}
if (!isSpotColorSubtractive)
{
for (uint8_t i = pixelFormat.getSpotColorChannelIndexStart(); i < pixelFormat.getSpotColorChannelIndexEnd(); ++i)
{
B_i[i] = PDFBlendFunction::blend(spotBlendMode, backdropColor[i], sourceColor[i]);
B_i[i] = PDFBlendFunction::blend(channelBlendModes[i], backdropColor[i], sourceColor[i]);
}
}
else
{
for (uint8_t i = pixelFormat.getSpotColorChannelIndexStart(); i < pixelFormat.getSpotColorChannelIndexEnd(); ++i)
{
B_i[i] = 1.0f - PDFBlendFunction::blend(spotBlendMode, 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
B_i[i] = 1.0f - PDFBlendFunction::blend(channelBlendModes[i], 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
}
}
}
@ -305,14 +394,14 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
{
for (uint8_t i = pixelFormat.getSpotColorChannelIndexStart(); i < pixelFormat.getSpotColorChannelIndexEnd(); ++i)
{
B_i[i] = PDFBlendFunction::blend(BlendMode::Normal, backdropColor[i], sourceColor[i]);
B_i[i] = PDFBlendFunction::blend(channelBlendModes[i], backdropColor[i], sourceColor[i]);
}
}
else
{
for (uint8_t i = pixelFormat.getSpotColorChannelIndexStart(); i < pixelFormat.getSpotColorChannelIndexEnd(); ++i)
{
B_i[i] = 1.0f - PDFBlendFunction::blend(BlendMode::Normal, 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
B_i[i] = 1.0f - PDFBlendFunction::blend(channelBlendModes[i], 1.0f - backdropColor[i], 1.0f - sourceColor[i]);
}
}
}
@ -532,6 +621,8 @@ void PDFTransparencyRenderer::performBeginTransparencyGroup(ProcessOrder order,
void PDFTransparencyRenderer::performEndTransparencyGroup(ProcessOrder order, const PDFTransparencyGroup& transparencyGroup)
{
Q_UNUSED(transparencyGroup);
if (order == ProcessOrder::AfterOperation)
{
// "Unblend" the initial backdrop from immediate backdrop, according to 11.4.8
@ -543,7 +634,8 @@ void PDFTransparencyRenderer::performEndTransparencyGroup(ProcessOrder order, co
PDFTransparencyGroupPainterData& targetData = m_transparencyGroupDataStack.back();
sourceData.immediateBackdrop.convertToColorSpace(getCMS(), targetData.renderingIntent, targetData.blendColorSpace, this);
PDFFloatBitmap::blend(sourceData, targetData, *getBackdrop(), *getInitialBackdrop(), sourceData.softMask, sourceData.alphaIsShape, sourceData.alphaFill, BlendMode::Normal);
PDFFloatBitmap::blend(sourceData.immediateBackdrop, targetData.immediateBackdrop, *getBackdrop(), *getInitialBackdrop(), sourceData.softMask,
sourceData.alphaIsShape, sourceData.alphaFill, BlendMode::Normal, 0xFFFF, PDFFloatBitmap::OverprintMode::NoOveprint);
}
}
@ -573,7 +665,7 @@ void PDFTransparencyRenderer::removeInitialBackdrop()
if (!qFuzzyIsNull(alpha_g_n))
{
for (const uint8_t i = colorChannelIndexStart; i < colorChannelIndexEnd; ++i)
for (uint8_t i = colorChannelIndexStart; i < colorChannelIndexEnd; ++i)
{
const PDFColorComponent C_0 = initialBackdropColorBuffer[i];
const PDFColorComponent C_n = immediateBackdropColorBuffer[i];

21
Pdf4QtLib/sources/pdftransparencyrenderer.h
View File

@ -134,6 +134,9 @@ public:
/// Returns buffer with pixel channels
PDFColorBuffer getPixel(size_t x, size_t y);
/// Returns constant buffer with pixel channels
PDFConstColorBuffer getPixel(size_t x, size_t y) const;
/// Returns buffer with all pixels
PDFColorBuffer getPixels();
@ -164,9 +167,19 @@ public:
/// Extract process colors into another bitmap
PDFFloatBitmap extractProcessColors();
enum class OverprintMode
{
NoOveprint, ///< No oveprint performed
Overprint_Mode_0, ///< Overprint performed (either backdrop or source color is selected)
Overprint_Mode_1, ///< Overprint performed (only nonzero source color is selected, otherwise backdrop)
};
/// Performs bitmap blending, pixel format of source and target must be the same.
/// Blending algorithm uses the one from chapter 11.4.8 in the PDF 2.0 specification.
/// Bitmap size must be equal for all three bitmaps (source, target and soft mask).
/// Oveprinting is also handled. You can specify a mask with active color channels.
/// If n-th bit in \p activeColorChannels variable is 1, then color channel is active;
/// otherwise backdrop color is selected (if overprint is active).
/// \param source Source bitmap
/// \param target Target bitmap
/// \param backdrop Backdrop
@ -175,14 +188,18 @@ public:
/// \param alphaIsShape Both soft mask and constant alpha are shapes and not opacity?
/// \param constantAlpha Constant alpha, can mean shape or opacity
/// \param mode Blend mode
void blend(const PDFFloatBitmap& source,
/// \param activeColorChannels Active color channels
/// \param overprintMode Overprint mode
static void blend(const PDFFloatBitmap& source,
PDFFloatBitmap& target,
const PDFFloatBitmap& backdrop,
const PDFFloatBitmap& initialBackdrop,
PDFFloatBitmap& softMask,
bool alphaIsShape,
PDFColorComponent constantAlpha,
BlendMode mode);
BlendMode mode,
uint32_t activeColorChannels,
OverprintMode overprintMode);
private:
void fillChannel(size_t channel, PDFColorComponent value);