diff --git a/src/inputsource.cpp b/src/inputsource.cpp
index ebbf749..e0f0882 100644
--- a/src/inputsource.cpp
+++ b/src/inputsource.cpp
@@ -38,6 +38,7 @@
 #include <QJsonObject>
 #include <QJsonArray>
 #include <QFile>
+#include <QColor>
 
 
 class ComplexF32SampleAdapter : public SampleAdapter {
@@ -264,7 +265,9 @@ void InputSource::readMetaData(const QString &filename)
 
 
     auto datatype = global["core:datatype"].toString();
-    if (datatype.compare("cf32_le") == 0) {
+    if (datatype.compare("cf64_le") == 0) {
+        sampleAdapter = std::make_unique<ComplexF64SampleAdapter>();
+    } else if (datatype.compare("cf32_le") == 0) {
         sampleAdapter = std::make_unique<ComplexF32SampleAdapter>();
     } else if (datatype.compare("ci32_le") == 0) {
         sampleAdapter = std::make_unique<ComplexS32SampleAdapter>();
@@ -339,10 +342,23 @@ void InputSource::readMetaData(const QString &filename)
                 auto frequencyRange = range_t<double>{freq_lower_edge, freq_upper_edge};
 
                 auto label = sigmf_annotation["core:label"].toString();
+                if (label.isEmpty()) {
+                    label = sigmf_annotation["core:description"].toString();
+                }
 
                 auto comment = sigmf_annotation["core:comment"].toString();
 
-                annotationList.emplace_back(sampleRange, frequencyRange, label, comment);
+                auto sigmf_color = sigmf_annotation["presentation:color"].toString();
+                // SigMF uses the format "#RRGGBBAA" for alpha-channel colors, QT uses "#AARRGGBB"
+                if ((sigmf_color.at(0) == '#') && (sigmf_color.length()) == 9) {
+                    sigmf_color = "#" + sigmf_color.mid(7,2) + sigmf_color.mid(1,6);
+                }
+                auto boxColor = QString::fromStdString("white");
+                if (QColor::isValidColor(sigmf_color)) {
+                    boxColor = sigmf_color;
+                }
+
+                annotationList.emplace_back(sampleRange, frequencyRange, label, comment, boxColor);
             }
         }
     }
@@ -397,13 +413,8 @@ void InputSource::openFile(const char *filename)
     annotationList.clear();
     QString metaFilename;
 
-    if (suffix == "sigmf-meta") {
+    if (suffix == "sigmf-meta" || suffix == "sigmf-data" || suffix == "sigmf-") {
         dataFilename = fileInfo.path() + "/" + fileInfo.completeBaseName() + ".sigmf-data";
-        metaFilename = filename;
-        readMetaData(metaFilename);
-    }
-    else if (suffix == "sigmf-data") {
-        dataFilename = filename;
         metaFilename = fileInfo.path() + "/" + fileInfo.completeBaseName() + ".sigmf-meta";
         readMetaData(metaFilename);
     }
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index dc62d76..da6bfe6 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -52,7 +52,9 @@ MainWindow::MainWindow()
     connect(dock->scalesCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableScales);
     connect(dock->annosCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableAnnotations);
     connect(dock->annosCheckBox, &QCheckBox::stateChanged, dock, &SpectrogramControls::enableAnnotations);
+    connect(dock->annoLabelCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableAnnoLabels);
     connect(dock->commentsCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableAnnotationCommentsTooltips);
+    connect(dock->annoColorCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableAnnoColors);
     connect(dock->cursorSymbolsSpinBox, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), plots, &PlotView::setCursorSegments);
 
     // Connect dock outputs
diff --git a/src/plotview.cpp b/src/plotview.cpp
index d1c6bea..d05b33c 100644
--- a/src/plotview.cpp
+++ b/src/plotview.cpp
@@ -51,6 +51,8 @@ PlotView::PlotView(InputSource *input) : cursors(this), viewRange({0, 0})
     enableScales(true);
 
     enableAnnotations(true);
+    enableAnnoLabels(true);
+    enableAnnoColors(true);
     enableAnnotationCommentsTooltips(true);
 
     addPlot(spectrogramPlot);
@@ -425,6 +427,7 @@ void PlotView::setCursorSegments(int segments)
     selectedSamples.maximum = selectedSamples.minimum + (segments * sampPerSeg + 0.5f);
 
     cursors.setSegments(segments);
+
     updateView();
     emitTimeSelection();
 }
@@ -432,6 +435,9 @@ void PlotView::setCursorSegments(int segments)
 void PlotView::setFFTAndZoom(int size, int zoom)
 {
     auto oldSamplesPerColumn = samplesPerColumn();
+    float oldPlotCenter = (verticalScrollBar()->value() + viewport()->height() / 2.0) / plotsHeight();
+    if (verticalScrollBar()->maximum() == 0)
+        oldPlotCenter = 0.5;
 
     // Set new FFT size
     fftSize = size;
@@ -439,15 +445,22 @@ void PlotView::setFFTAndZoom(int size, int zoom)
         spectrogramPlot->setFFTSize(size);
 
     // Set new zoom level
-    zoomLevel = zoom;
-    if (spectrogramPlot != nullptr)
-        spectrogramPlot->setZoomLevel(zoom);
+    zoomLevel = std::max(1,zoom);
+    nfftSkip = std::max(1,-1*zoom);
+    if (spectrogramPlot != nullptr) {
+        spectrogramPlot->setZoomLevel(zoomLevel);
+        spectrogramPlot->setSkip(nfftSkip);
+    }
 
     // Update horizontal (time) scrollbar
     horizontalScrollBar()->setSingleStep(10);
     horizontalScrollBar()->setPageStep(100);
 
     updateView(true, samplesPerColumn() < oldSamplesPerColumn);
+
+    // maintain the relative position of the vertical scroll bar
+    if (verticalScrollBar()->maximum())
+        verticalScrollBar()->setValue((int )(oldPlotCenter * plotsHeight() - viewport()->height() / 2.0 + 0.5f));
 }
 
 void PlotView::setPowerMin(int power)
@@ -568,7 +581,7 @@ void PlotView::resizeEvent(QResizeEvent * event)
 
 size_t PlotView::samplesPerColumn()
 {
-    return fftSize / zoomLevel;
+    return fftSize * nfftSkip / zoomLevel;
 }
 
 void PlotView::scrollContentsBy(int dx, int dy)
@@ -604,6 +617,7 @@ void PlotView::updateView(bool reCenter, bool expanding)
     }
     horizontalScrollBar()->setMaximum(std::max(0, sampleToColumn(mainSampleSource->count()) - width()));
     verticalScrollBar()->setMaximum(std::max(0, plotsHeight() - viewport()->height()));
+
     if (expanding) {
         updateViewRange(reCenter);
     }
@@ -647,6 +661,14 @@ void PlotView::enableAnnotations(bool enabled)
     viewport()->update();
 }
 
+void PlotView::enableAnnoLabels(bool enabled)
+{
+    if (spectrogramPlot != nullptr)
+        spectrogramPlot->enableAnnoLabels(enabled);
+
+    viewport()->update();
+}
+
 void PlotView::enableAnnotationCommentsTooltips(bool enabled)
 {
     annotationCommentsEnabled = enabled;
@@ -654,6 +676,14 @@ void PlotView::enableAnnotationCommentsTooltips(bool enabled)
     viewport()->update();
 }
 
+void PlotView::enableAnnoColors(bool enabled)
+{
+    if (spectrogramPlot != nullptr)
+        spectrogramPlot->enableAnnoColors(enabled);
+    
+    viewport()->update();
+}
+
 int PlotView::sampleToColumn(size_t sample)
 {
     return sample / samplesPerColumn();
diff --git a/src/plotview.h b/src/plotview.h
index 326d547..c80ff1c 100644
--- a/src/plotview.h
+++ b/src/plotview.h
@@ -47,7 +47,9 @@ public slots:
     void enableCursors(bool enabled);
     void enableScales(bool enabled);
     void enableAnnotations(bool enabled);
+    void enableAnnoLabels(bool enabled);
     void enableAnnotationCommentsTooltips(bool enabled);
+    void enableAnnoColors(bool enabled);
     void invalidateEvent() override;
     void repaint();
     void setCursorSegments(int segments);
@@ -77,6 +79,7 @@ public slots:
 
     int fftSize = 1024;
     int zoomLevel = 1;
+    int nfftSkip = 1;
     int powerMin;
     int powerMax;
     bool cursorsEnabled;
diff --git a/src/samplesource.h b/src/samplesource.h
index 3f0b299..58789f6 100644
--- a/src/samplesource.h
+++ b/src/samplesource.h
@@ -26,6 +26,7 @@
 #include "util.h"
 #include <QString>
 #include <QObject>
+#include <QColor>
 
 class Annotation
 {
@@ -34,11 +35,12 @@ class Annotation
     range_t<double> frequencyRange;
     QString label;
     QString comment;
+    QColor boxColor;
 
     Annotation(range_t<size_t> sampleRange, range_t<double>frequencyRange, QString label,
-               QString comment)
+               QString comment, QColor boxColor)
       : sampleRange(sampleRange), frequencyRange(frequencyRange), label(label),
-        comment(comment) {}
+        comment(comment), boxColor(boxColor) {}
 };
 
 template<typename T>
diff --git a/src/spectrogramcontrols.cpp b/src/spectrogramcontrols.cpp
index 0e0f9aa..b2fa380 100644
--- a/src/spectrogramcontrols.cpp
+++ b/src/spectrogramcontrols.cpp
@@ -46,13 +46,13 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
     layout->addRow(new QLabel(tr("<b>Spectrogram</b>")));
 
     fftSizeSlider = new QSlider(Qt::Horizontal, widget);
-    fftSizeSlider->setRange(4, 13);
+    fftSizeSlider->setRange(4, 16);
     fftSizeSlider->setPageStep(1);
 
     layout->addRow(new QLabel(tr("FFT size:")), fftSizeSlider);
 
     zoomLevelSlider = new QSlider(Qt::Horizontal, widget);
-    zoomLevelSlider->setRange(0, 10);
+    zoomLevelSlider->setRange(-6, 10);
     zoomLevelSlider->setPageStep(1);
 
     layout->addRow(new QLabel(tr("Zoom:")), zoomLevelSlider);
@@ -99,8 +99,12 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
 
     annosCheckBox = new QCheckBox(widget);
     layout->addRow(new QLabel(tr("Display Annotations:")), annosCheckBox);
+    annoLabelCheckBox = new QCheckBox(widget);
+    layout->addRow(new QLabel(tr("Annotation Labels:")), annoLabelCheckBox);
     commentsCheckBox = new QCheckBox(widget);
-    layout->addRow(new QLabel(tr("Display annotation comments tooltips:")), commentsCheckBox);
+    layout->addRow(new QLabel(tr("Annotation comments:")), commentsCheckBox);
+    annoColorCheckBox = new QCheckBox(widget);
+    layout->addRow(new QLabel(tr("Annotation Colors:")), annoColorCheckBox);
 
     widget->setLayout(layout);
     setWidget(widget);
@@ -136,7 +140,8 @@ void SpectrogramControls::setDefaults()
     cursorSymbolsSpinBox->setValue(1);
 
     annosCheckBox->setCheckState(Qt::Checked);
-    commentsCheckBox->setCheckState(Qt::Checked);
+    annoLabelCheckBox->setCheckState(Qt::Checked);
+    annoColorCheckBox->setCheckState(Qt::Checked);
 
     // Try to set the sample rate from the last-used value
     QSettings settings;
@@ -151,7 +156,13 @@ void SpectrogramControls::setDefaults()
 void SpectrogramControls::fftOrZoomChanged(void)
 {
     int fftSize = pow(2, fftSizeSlider->value());
-    int zoomLevel = std::min(fftSize, (int)pow(2, zoomLevelSlider->value()));
+    int zoomLevel = zoomLevelSlider->value();
+    if (zoomLevel >= 0)
+        // zooming in by power-of-two steps
+        zoomLevel = std::min(fftSize, (int)pow(2, zoomLevel));
+    else
+        // zooming out (skipping FFTs) by power-of-two steps
+        zoomLevel = -1*std::min(fftSize, (int)pow(2, -1*zoomLevel));
     emit fftOrZoomChanged(fftSize, zoomLevel);
 }
 
diff --git a/src/spectrogramcontrols.h b/src/spectrogramcontrols.h
index 69e7d60..e0c69ca 100644
--- a/src/spectrogramcontrols.h
+++ b/src/spectrogramcontrols.h
@@ -75,5 +75,7 @@ private slots:
     QLabel *symbolPeriodLabel;
     QCheckBox *scalesCheckBox;
     QCheckBox *annosCheckBox;
+    QCheckBox *annoLabelCheckBox;
     QCheckBox *commentsCheckBox;
+    QCheckBox *annoColorCheckBox;
 };
diff --git a/src/spectrogramplot.cpp b/src/spectrogramplot.cpp
index 3ab57ec..9a2dd4f 100644
--- a/src/spectrogramplot.cpp
+++ b/src/spectrogramplot.cpp
@@ -35,11 +35,14 @@ SpectrogramPlot::SpectrogramPlot(std::shared_ptr<SampleSource<std::complex<float
 {
     setFFTSize(fftSize);
     zoomLevel = 1;
+    nfftSkip = 1;
     powerMax = 0.0f;
     powerMin = -50.0f;
     sampleRate = 0;
     frequencyScaleEnabled = false;
     sigmfAnnotationsEnabled = true;
+    sigmfAnnotationLabels = true;
+    sigmfAnnotationColors = true;
 
     for (int i = 0; i < 256; i++) {
         float p = (float)i / 256;
@@ -194,8 +197,13 @@ void SpectrogramPlot::paintAnnotations(QPainter &painter, QRect &rect, range_t<s
             int height = (a.frequencyRange.maximum - a.frequencyRange.minimum) / sampleRate * rect.height();
             int width = (a.sampleRange.maximum - a.sampleRange.minimum) / getStride();
 
-            // Draw the label 2 pixels above the box
-            painter.drawText(x, y - 2, a.label);
+            if (sigmfAnnotationColors) {
+                painter.setPen(a.boxColor);
+            }
+            if (sigmfAnnotationLabels) {
+                // Draw the label 2 pixels above the box
+                painter.drawText(x, y - 2, a.label);
+            }
             painter.drawRect(x, y, width, height);
 
             visibleAnnotationLocations.emplace_back(a, x, y, width, height);
@@ -242,7 +250,7 @@ void SpectrogramPlot::paintMid(QPainter &painter, QRect &rect, range_t<size_t> s
 
 QPixmap* SpectrogramPlot::getPixmapTile(size_t tile)
 {
-    QPixmap *obj = pixmapCache.object(TileCacheKey(fftSize, zoomLevel, tile));
+    QPixmap *obj = pixmapCache.object(TileCacheKey(fftSize, zoomLevel, nfftSkip, tile));
     if (obj != 0)
         return obj;
 
@@ -261,13 +269,13 @@ QPixmap* SpectrogramPlot::getPixmapTile(size_t tile)
         }
     }
     obj->convertFromImage(image);
-    pixmapCache.insert(TileCacheKey(fftSize, zoomLevel, tile), obj);
+    pixmapCache.insert(TileCacheKey(fftSize, zoomLevel, nfftSkip, tile), obj);
     return obj;
 }
 
 float* SpectrogramPlot::getFFTTile(size_t tile)
 {
-    std::array<float, tileSize>* obj = fftCache.object(TileCacheKey(fftSize, zoomLevel, tile));
+    std::array<float, tileSize>* obj = fftCache.object(TileCacheKey(fftSize, zoomLevel, nfftSkip, tile));
     if (obj != nullptr)
         return obj->data();
 
@@ -279,7 +287,7 @@ float* SpectrogramPlot::getFFTTile(size_t tile)
         sample += getStride();
         ptr += fftSize;
     }
-    fftCache.insert(TileCacheKey(fftSize, zoomLevel, tile), destStorage);
+    fftCache.insert(TileCacheKey(fftSize, zoomLevel, nfftSkip, tile), destStorage);
     return destStorage->data();
 }
 
@@ -316,7 +324,7 @@ void SpectrogramPlot::getLine(float *dest, size_t sample)
 
 int SpectrogramPlot::getStride()
 {
-    return fftSize / zoomLevel;
+    return fftSize * nfftSkip / zoomLevel;
 }
 
 float SpectrogramPlot::getTunerPhaseInc()
@@ -397,6 +405,11 @@ void SpectrogramPlot::setZoomLevel(int zoom)
     zoomLevel = zoom;
 }
 
+void SpectrogramPlot::setSkip(int skip)
+{
+    nfftSkip = skip;
+}
+
 void SpectrogramPlot::setSampleRate(double rate)
 {
     sampleRate = rate;
@@ -417,6 +430,16 @@ bool SpectrogramPlot::isAnnotationsEnabled(void)
     return sigmfAnnotationsEnabled;
 }
 
+void SpectrogramPlot::enableAnnoLabels(bool enabled)
+{
+    sigmfAnnotationLabels = enabled;
+}
+
+void SpectrogramPlot::enableAnnoColors(bool enabled)
+{
+    sigmfAnnotationColors = enabled;
+}
+
 bool SpectrogramPlot::tunerEnabled()
 {
     return (tunerTransform->subscriberCount() > 0);
diff --git a/src/spectrogramplot.h b/src/spectrogramplot.h
index 2e52cb4..cf9d1b0 100644
--- a/src/spectrogramplot.h
+++ b/src/spectrogramplot.h
@@ -52,7 +52,9 @@ class SpectrogramPlot : public Plot
     bool tunerEnabled();
     void enableScales(bool enabled);
     void enableAnnotations(bool enabled);
+    void enableAnnoLabels(bool enabled);
     bool isAnnotationsEnabled();
+    void enableAnnoColors(bool enabled);
     QString *mouseAnnotationComment(const QMouseEvent *event);
 
 public slots:
@@ -60,6 +62,7 @@ public slots:
     void setPowerMax(int power);
     void setPowerMin(int power);
     void setZoomLevel(int zoom);
+    void setSkip(int skip);
     void tunerMoved();
 
 private:
@@ -76,11 +79,14 @@ public slots:
 
     int fftSize;
     int zoomLevel;
+    int nfftSkip;
     float powerMax;
     float powerMin;
     double sampleRate;
     bool frequencyScaleEnabled;
     bool sigmfAnnotationsEnabled;
+    bool sigmfAnnotationLabels;
+    bool sigmfAnnotationColors;
 
     Tuner tuner;
     std::shared_ptr<TunerTransform> tunerTransform;
@@ -100,20 +106,23 @@ class TileCacheKey
 {
 
 public:
-    TileCacheKey(int fftSize, int zoomLevel, size_t sample) {
+    TileCacheKey(int fftSize, int zoomLevel, int nfftSkip, size_t sample) {
         this->fftSize = fftSize;
         this->zoomLevel = zoomLevel;
+        this->nfftSkip = nfftSkip;
         this->sample = sample;
     }
 
     bool operator==(const TileCacheKey &k2) const {
         return (this->fftSize == k2.fftSize) &&
                (this->zoomLevel == k2.zoomLevel) &&
+               (this->nfftSkip == k2.nfftSkip) &&
                (this->sample == k2.sample);
     }
 
     int fftSize;
     int zoomLevel;
+    int nfftSkip;
     size_t sample;
 };