diff --git a/Pdf4QtLib/sources/pdfdiff.cpp b/Pdf4QtLib/sources/pdfdiff.cpp
index 7284204..98e9246 100644
--- a/Pdf4QtLib/sources/pdfdiff.cpp
+++ b/Pdf4QtLib/sources/pdfdiff.cpp
@@ -16,7 +16,13 @@
 //    along with PDF4QT.  If not, see <https://www.gnu.org/licenses/>.
 
 #include "pdfdiff.h"
+#include "pdfrenderer.h"
 #include "pdfdocumenttextflow.h"
+#include "pdfexecutionpolicy.h"
+#include "pdffont.h"
+#include "pdfcms.h"
+#include "pdfcompiler.h"
+#include "pdfconstants.h"
 
 #include <QtConcurrent/QtConcurrent>
 
@@ -29,6 +35,7 @@ PDFDiff::PDFDiff(QObject* parent) :
     m_leftDocument(nullptr),
     m_rightDocument(nullptr),
     m_options(Asynchronous),
+    m_epsilon(0.0001),
     m_cancelled(false)
 {
 
@@ -141,30 +148,11 @@ PDFDiffResult PDFDiff::perform()
     {
         ProgressStartupInfo info;
         info.showDialog = false;
-        info.text = tr("");
+        info.text = tr("Comparing documents.");
         m_progress->start(StepLast, std::move(info));
     }
 
-    // StepExtractContentLeftDocument
-    stepProgress();
-
-    // StepExtractContentRightDocument
-    stepProgress();
-
-    // StepExtractTextLeftDocument
-    pdf::PDFDocumentTextFlowFactory factoryLeftDocumentTextFlow;
-    factoryLeftDocumentTextFlow.setCalculateBoundingBoxes(true);
-    PDFDocumentTextFlow leftTextFlow = factoryLeftDocumentTextFlow.create(m_leftDocument, leftPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
-    stepProgress();
-
-    // StepExtractTextRightDocument
-    pdf::PDFDocumentTextFlowFactory factoryRightDocumentTextFlow;
-    factoryRightDocumentTextFlow.setCalculateBoundingBoxes(true);
-    PDFDocumentTextFlow rightTextFlow = factoryRightDocumentTextFlow.create(m_rightDocument, rightPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
-    stepProgress();
-
-    // StepCompare
-    stepProgress();
+    performSteps(leftPages, rightPages);
 
     if (m_progress)
     {
@@ -182,6 +170,102 @@ void PDFDiff::stepProgress()
     }
 }
 
+struct PDFDiffPageContext
+{
+    PDFInteger pageIndex = 0;
+    PDFPrecompiledPage::GraphicPieceInfos graphicPieces;
+};
+
+void PDFDiff::performSteps(const std::vector<PDFInteger>& leftPages, const std::vector<PDFInteger>& rightPages)
+{
+    std::vector<PDFDiffPageContext> leftPreparedPages;
+    std::vector<PDFDiffPageContext> rightPreparedPages;
+
+    auto createDiffPageContext = [](auto pageIndex)
+    {
+       PDFDiffPageContext context;
+       context.pageIndex = pageIndex;
+       return context;
+    };
+    std::transform(leftPages.cbegin(), leftPages.cend(), std::back_inserter(leftPreparedPages), createDiffPageContext);
+    std::transform(rightPages.cbegin(), rightPages.cend(), std::back_inserter(rightPreparedPages), createDiffPageContext);
+
+    // StepExtractContentLeftDocument
+    if (!m_cancelled)
+    {
+        PDFFontCache fontCache(DEFAULT_FONT_CACHE_LIMIT, DEFAULT_REALIZED_FONT_CACHE_LIMIT);
+        PDFOptionalContentActivity optionalContentActivity(m_leftDocument, pdf::OCUsage::View, nullptr);
+        fontCache.setDocument(pdf::PDFModifiedDocument(const_cast<pdf::PDFDocument*>(m_leftDocument), &optionalContentActivity));
+
+        PDFCMSManager cmsManager(nullptr);
+        cmsManager.setDocument(m_leftDocument);
+        PDFCMSPointer cms = cmsManager.getCurrentCMS();
+
+        auto fillPageContext = [&, this](PDFDiffPageContext& context)
+        {
+            PDFPrecompiledPage compiledPage;
+            constexpr PDFRenderer::Features features = PDFRenderer::IgnoreOptionalContent;
+            PDFRenderer renderer(m_leftDocument, &fontCache, cms.data(), &optionalContentActivity, features, pdf::PDFMeshQualitySettings());
+            renderer.compile(&compiledPage, context.pageIndex);
+
+            PDFReal epsilon = calculateEpsilonForPage(m_leftDocument->getCatalog()->getPage(context.pageIndex));
+            context.graphicPieces = compiledPage.calculateGraphicPieceInfos(epsilon);
+        };
+        PDFExecutionPolicy::execute(PDFExecutionPolicy::Scope::Page, leftPreparedPages.begin(), leftPreparedPages.end(), fillPageContext);
+        stepProgress();
+    }
+
+    // StepExtractContentRightDocument
+    if (!m_cancelled)
+    {
+        PDFFontCache fontCache(DEFAULT_FONT_CACHE_LIMIT, DEFAULT_REALIZED_FONT_CACHE_LIMIT);
+        PDFOptionalContentActivity optionalContentActivity(m_rightDocument, pdf::OCUsage::View, nullptr);
+        fontCache.setDocument(pdf::PDFModifiedDocument(const_cast<pdf::PDFDocument*>(m_rightDocument), &optionalContentActivity));
+
+        PDFCMSManager cmsManager(nullptr);
+        cmsManager.setDocument(m_rightDocument);
+        PDFCMSPointer cms = cmsManager.getCurrentCMS();
+
+        auto fillPageContext = [&, this](PDFDiffPageContext& context)
+        {
+            PDFPrecompiledPage compiledPage;
+            constexpr PDFRenderer::Features features = PDFRenderer::IgnoreOptionalContent;
+            PDFRenderer renderer(m_rightDocument, &fontCache, cms.data(), &optionalContentActivity, features, pdf::PDFMeshQualitySettings());
+            renderer.compile(&compiledPage, context.pageIndex);
+
+            PDFReal epsilon = calculateEpsilonForPage(m_leftDocument->getCatalog()->getPage(context.pageIndex));
+            context.graphicPieces = compiledPage.calculateGraphicPieceInfos(epsilon);
+        };
+
+        PDFExecutionPolicy::execute(PDFExecutionPolicy::Scope::Page, rightPreparedPages.begin(), rightPreparedPages.end(), fillPageContext);
+        stepProgress();
+    }
+
+    // StepExtractTextLeftDocument
+    if (!m_cancelled)
+    {
+        pdf::PDFDocumentTextFlowFactory factoryLeftDocumentTextFlow;
+        factoryLeftDocumentTextFlow.setCalculateBoundingBoxes(true);
+        PDFDocumentTextFlow leftTextFlow = factoryLeftDocumentTextFlow.create(m_leftDocument, leftPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
+        stepProgress();
+    }
+
+    // StepExtractTextRightDocument
+    if (!m_cancelled)
+    {
+        pdf::PDFDocumentTextFlowFactory factoryRightDocumentTextFlow;
+        factoryRightDocumentTextFlow.setCalculateBoundingBoxes(true);
+        PDFDocumentTextFlow rightTextFlow = factoryRightDocumentTextFlow.create(m_rightDocument, rightPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
+        stepProgress();
+    }
+
+    // StepCompare
+    if (!m_cancelled)
+    {
+        stepProgress();
+    }
+}
+
 void PDFDiff::onComparationPerformed()
 {
     m_cancelled = false;
@@ -189,6 +273,19 @@ void PDFDiff::onComparationPerformed()
     emit comparationFinished();
 }
 
+PDFReal PDFDiff::calculateEpsilonForPage(const PDFPage* page) const
+{
+    Q_ASSERT(page);
+
+    QRectF mediaBox = page->getMediaBox();
+
+    PDFReal width = mediaBox.width();
+    PDFReal height = mediaBox.height();
+    PDFReal factor = qMax(width, height);
+
+    return factor * m_epsilon;
+}
+
 PDFDiffResult::PDFDiffResult() :
     m_result(true)
 {
diff --git a/Pdf4QtLib/sources/pdfdiff.h b/Pdf4QtLib/sources/pdfdiff.h
index a5c177d..ce3a046 100644
--- a/Pdf4QtLib/sources/pdfdiff.h
+++ b/Pdf4QtLib/sources/pdfdiff.h
@@ -117,15 +117,24 @@ private:
 
     PDFDiffResult perform();
     void stepProgress();
+    void performSteps(const std::vector<PDFInteger>& leftPages,
+                      const std::vector<PDFInteger>& rightPages);
 
     void onComparationPerformed();
 
+    /// Calculates real epsilon for a page. Epsilon is used in page
+    /// comparation process, where points closer that epsilon
+    /// are recognized as equal.
+    /// \param page Page
+    PDFReal calculateEpsilonForPage(const PDFPage* page) const;
+
     PDFProgress* m_progress;
     const PDFDocument* m_leftDocument;
     const PDFDocument* m_rightDocument;
     PDFClosedIntervalSet m_pagesForLeftDocument;
     PDFClosedIntervalSet m_pagesForRightDocument;
     Options m_options;
+    PDFReal m_epsilon;
     std::atomic_bool m_cancelled;
     PDFDiffResult m_result;
 
diff --git a/Pdf4QtLib/sources/pdfdrawwidget.h b/Pdf4QtLib/sources/pdfdrawwidget.h
index 3c8e6f2..998e14a 100644
--- a/Pdf4QtLib/sources/pdfdrawwidget.h
+++ b/Pdf4QtLib/sources/pdfdrawwidget.h
@@ -103,7 +103,7 @@ public:
     void addInputInterface(IDrawWidgetInputInterface* inputInterface);
 
 signals:
-    void pageRenderingErrorsChanged(PDFInteger pageIndex, int errorsCount);
+    void pageRenderingErrorsChanged(pdf::PDFInteger pageIndex, int errorsCount);
 
 private:
     void updateRendererImpl();
diff --git a/Pdf4QtLib/sources/pdfpainter.cpp b/Pdf4QtLib/sources/pdfpainter.cpp
index 7988881..d1d8d7c 100644
--- a/Pdf4QtLib/sources/pdfpainter.cpp
+++ b/Pdf4QtLib/sources/pdfpainter.cpp
@@ -20,6 +20,7 @@
 #include "pdfcms.h"
 
 #include <QPainter>
+#include <QCryptographicHash>
 
 namespace pdf
 {
@@ -831,4 +832,146 @@ void PDFPrecompiledPage::finalize(qint64 compilingTimeNS, QList<PDFRenderError>
     }
 }
 
+PDFPrecompiledPage::GraphicPieceInfos PDFPrecompiledPage::calculateGraphicPieceInfos(PDFReal epsilon) const
+{
+    GraphicPieceInfos infos;
+
+    struct State
+    {
+        QMatrix matrix;
+    };
+    std::stack<State> stateStack;
+    stateStack.emplace();
+
+    // Check, if epsilon is not too small
+    if (qFuzzyIsNull(epsilon))
+    {
+        epsilon = 0.000001;
+    }
+    PDFReal factor = 1.0 / epsilon;
+
+    // Process all instructions
+    for (const Instruction& instruction : m_instructions)
+    {
+        switch (instruction.type)
+        {
+            case InstructionType::DrawPath:
+            {
+                const PathPaintData& data = m_paths[instruction.dataIndex];
+
+                GraphicPieceInfo info;
+                QByteArray serializedPath;
+
+                // Serialize data
+                if (true)
+                {
+                    QDataStream stream(&serializedPath, QIODevice::WriteOnly);
+
+                    stream << data.isText;
+                    stream << data.pen;
+                    stream << data.brush;
+
+                    // Translate map to page coordinates
+                    QPainterPath pagePath = stateStack.top().matrix.map(data.path);
+
+                    info.type = data.isText ? GraphicPieceInfo::Type::Text : GraphicPieceInfo::Type::VectorGraphics;
+                    info.boundingRect = pagePath.controlPointRect();
+
+                    const int elementCount = pagePath.elementCount();
+                    for (int i = 0; i < elementCount; ++i)
+                    {
+                        QPainterPath::Element element = pagePath.elementAt(i);
+
+                        PDFReal roundedX = qRound(element.x * factor);
+                        PDFReal roundedY = qRound(element.y * factor);
+
+                        stream << roundedX;
+                        stream << roundedY;
+                        stream << element.type;
+                    }
+                }
+
+                QByteArray hash = QCryptographicHash::hash(serializedPath, QCryptographicHash::Sha512);
+                Q_ASSERT(QCryptographicHash::hashLength(QCryptographicHash::Sha512) == 64);
+
+                size_t size = qMin<size_t>(hash.length(), info.hash.size());
+                std::copy(hash.data(), hash.data() + size, info.hash.data());
+
+                infos.emplace_back(std::move(info));
+                break;
+            }
+
+            case InstructionType::DrawImage:
+            {
+                /*const ImageData& data = m_images[instruction.dataIndex];
+                const QImage& image = data.image;
+
+                painter->save();
+
+                QMatrix imageTransform(1.0 / image.width(), 0, 0, 1.0 / image.height(), 0, 0);
+                QMatrix worldMatrix = imageTransform * painter->worldMatrix();
+
+                // Jakub Melka: Because Qt uses opposite axis direction than PDF, then we must transform the y-axis
+                // to the opposite (so the image is then unchanged)
+                worldMatrix.translate(0, image.height());
+                worldMatrix.scale(1, -1);
+
+                painter->setWorldMatrix(worldMatrix);
+                painter->drawImage(0, 0, image);
+                painter->restore();*/
+                break;
+            }
+
+            case InstructionType::DrawMesh:
+            {
+                /*const MeshPaintData& data = m_meshes[instruction.dataIndex];
+
+                painter->save();
+                painter->setWorldMatrix(pagePointToDevicePointMatrix);
+                data.mesh.paint(painter, data.alpha);
+                painter->restore();*/
+                break;
+            }
+
+            case InstructionType::Clip:
+            {
+                // Do nothing, we are just collecting information
+                break;
+            }
+
+            case InstructionType::SaveGraphicState:
+            {
+                stateStack.push(stateStack.top());
+                break;
+            }
+
+            case InstructionType::RestoreGraphicState:
+            {
+                stateStack.pop();
+                break;
+            }
+
+            case InstructionType::SetWorldMatrix:
+            {
+                stateStack.top().matrix = m_matrices[instruction.dataIndex];
+                break;
+            }
+
+            case InstructionType::SetCompositionMode:
+            {
+                // Do nothing, we are just collecting information
+                break;
+            }
+
+            default:
+            {
+                Q_ASSERT(false);
+                break;
+            }
+        }
+    }
+
+    return infos;
+}
+
 }   // namespace pdf
diff --git a/Pdf4QtLib/sources/pdfpainter.h b/Pdf4QtLib/sources/pdfpainter.h
index 7a4e741..ecf872a 100644
--- a/Pdf4QtLib/sources/pdfpainter.h
+++ b/Pdf4QtLib/sources/pdfpainter.h
@@ -234,6 +234,30 @@ public:
     PDFSnapInfo* getSnapInfo() { return &m_snapInfo; }
     const PDFSnapInfo* getSnapInfo() const { return &m_snapInfo; }
 
+    struct GraphicPieceInfo
+    {
+        enum class Type
+        {
+            Unknown,
+            Text,
+            VectorGraphics,
+            Image
+        };
+
+        Type type = Type::Unknown;
+        QRectF boundingRect;
+        std::array<uint8_t, 64> hash = { };
+    };
+
+    using GraphicPieceInfos = std::vector<GraphicPieceInfo>;
+
+    /// Creates information about piece of graphic in this page,
+    /// for example, for comparation reasons. Parameter \p epsilon
+    /// is for numerical precision - values under epsilon are considered
+    /// as equal.
+    /// \param epsilon Epsilon
+    GraphicPieceInfos calculateGraphicPieceInfos(PDFReal epsilon) const;
+
 private:
     struct PathPaintData
     {