a:pic (Picture)

<p:pic xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main" xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
  <p:nvPicPr>
    <p:cNvPr id="1" name="Picture 1"/>
    <p:cNvPicPr/>
    <p:nvPr/>
  </p:nvPicPr>
  <p:blipFill>
    <a:blip r:embed="rId2" cstate="print"/>
    <a:stretch>
      <a:fillRect/>
    </a:stretch>
  </p:blipFill>
  <p:spPr>
    <a:xfrm>
      <a:off x="1000000" y="1000000"/>
      <a:ext cx="3000000" cy="2250000"/>
    </a:xfrm>
    <a:prstGeom prst="rect">
      <a:avLst/>
    </a:prstGeom>
  </p:spPr>
</p:pic>

using DocumentFormat.OpenXml.Presentation;
using DocumentFormat.OpenXml.Drawing;
using DocumentFormat.OpenXml;

var pic = new Picture();

// Non-visual properties
var nvPicPr = new NonVisualPictureProperties();
nvPicPr.Append(new NonVisualDrawingProperties { Id = 1, Name = "Picture 1" });
nvPicPr.Append(new NonVisualPictureDrawingProperties());
nvPicPr.Append(new PictureNonVisualProperties());
pic.Append(nvPicPr);

// Blip fill (image reference)
var blipFill = new BlipFillProperties();
var blip = new Blip { Embed = "rId2", CompressionState = BlipCompressionValues.Print };
blipFill.Append(blip);
var stretch = new Stretch();
stretch.Append(new FillRectangle());
blipFill.Append(stretch);
pic.Append(blipFill);

// Shape properties (frame sizing)
var spPr = new ShapeProperties();
var xfrm = new Transform2D();
xfrm.Append(new Offset { X = 1000000, Y = 1000000 });
xfrm.Append(new Extents { Cx = 3000000, Cy = 2250000 });
spPr.Append(xfrm);

var prstGeom = new PresetGeometry { Preset = ShapeTypeValues.Rectangle };
prstGeom.Append(new AdjustmentValueList());
spPr.Append(prstGeom);
pic.Append(spPr);

<p:pic xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main" xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
  <p:nvPicPr>
    <p:cNvPr id="2" name="Picture 2"/>
    <p:cNvPicPr/>
    <p:nvPr/>
  </p:nvPicPr>
  <p:blipFill>
    <a:blip r:embed="rId3"/>
    <a:stretch>
      <a:fillRect/>
    </a:stretch>
  </p:blipFill>
  <p:spPr>
    <a:xfrm>
      <a:off x="2000000" y="1500000"/>
      <a:ext cx="2500000" cy="2000000"/>
    </a:xfrm>
    <a:prstGeom prst="rect">
      <a:avLst/>
    </a:prstGeom>
    <a:ln w="25400">
      <a:solidFill>
        <a:srgbClr val="000000"/>
      </a:solidFill>
    </a:ln>
    <a:effectLst>
      <a:outerShdw blurRad="76200" dist="50800" dir="2700000">
        <a:srgbClr val="000000">
          <a:alpha val="50000"/>
        </a:srgbClr>
      </a:outerShdw>
    </a:effectLst>
  </p:spPr>
</p:pic>

var pic = new Picture();

var nvPicPr = new NonVisualPictureProperties();
nvPicPr.Append(new NonVisualDrawingProperties { Id = 2, Name = "Picture 2" });
nvPicPr.Append(new NonVisualPictureDrawingProperties());
nvPicPr.Append(new PictureNonVisualProperties());
pic.Append(nvPicPr);

var blipFill = new BlipFillProperties();
blipFill.Append(new Blip { Embed = "rId3" });
blipFill.Append(new Stretch { FillRectangle = new FillRectangle() });
pic.Append(blipFill);

var spPr = new ShapeProperties();
var xfrm = new Transform2D();
xfrm.Append(new Offset { X = 2000000, Y = 1500000 });
xfrm.Append(new Extents { Cx = 2500000, Cy = 2000000 });
spPr.Append(xfrm);

var prstGeom = new PresetGeometry { Preset = ShapeTypeValues.Rectangle };
prstGeom.Append(new AdjustmentValueList());
spPr.Append(prstGeom);

var ln = new Outline { Width = 25400 };
var fill = new SolidFill();
fill.Append(new RgbColorModelHex { Val = "000000" });
ln.Append(fill);
spPr.Append(ln);

var effectLst = new EffectList();
var outerShdw = new OuterShadow { BlurRadius = 76200, Distance = 50800, Direction = 2700000 };
var color = new RgbColorModelHex { Val = "000000" };
color.Append(new Alpha { Val = 50000 });
outerShdw.Append(color);
effectLst.Append(outerShdw);
spPr.Append(effectLst);

pic.Append(spPr);