PM> Install-Package Spire.Presentation

using Spire.Presentation;
using Spire.Presentation.Collections;
using System.Drawing;

namespace ExtractImagesFromPresentation
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Presentation class
            Presentation ppt = new Presentation();
            //Load a PowerPoint presentation
            ppt.LoadFromFile(@"Template.pptx");

            //Get the image collection of the presentation
            ImageCollection imageCollection = ppt.Images;

            //Iterate through the images in the collection
            for (int i = 0; i < imageCollection.Count; i++)
            {
                //Extract the images 
                imageCollection[i].Image.Save(string.Format(@"Presentation\Images{0}.png", i));
            }

            ppt.Dispose();
        }
    }
}

Imports Spire.Presentation
Imports Spire.Presentation.Collections

Namespace ExtractImagesFromPresentation
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Presentation class
            Dim ppt As Presentation = New Presentation()
            'Load a PowerPoint presentation
            ppt.LoadFromFile("Template.pptx")

            'Get the image collection of the presentation
            Dim imageCollection As ImageCollection = ppt.Images

            'Iterate through the images in the collection
            For i As Integer = 0 To imageCollection.Count - 1
                'Extract the images 
                imageCollection(i).Image.Save(String.Format("Presentation\Images{0}.png", i))
            Next

            ppt.Dispose()
        End Sub
    End Class
End Namespace

using Spire.Presentation;

namespace ExtractImagesFromSlide
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Presentation class
            Presentation ppt = new Presentation();
            //Load a PowerPoint presentation
            ppt.LoadFromFile(@"Template4.pptx");

            //Get the first slide
            ISlide slide = ppt.Slides[0];

            int i = 0;
            //Iterate through all shapes on the first slide
            foreach (IShape s in slide.Shapes)
            {
                //Check if the shape is of SlidePicture type
                if (s is SlidePicture)
                {
                    //Extract the image
                    SlidePicture ps = s as SlidePicture;
                    ps.PictureFill.Picture.EmbedImage.Image.Save(string.Format(@"Slide\Images{0}.png", i));
                    i++;
                }
                //Check if the shape is of PictureShape type
                if (s is PictureShape)
                {
                    //Extract the image
                    PictureShape ps = s as PictureShape;
                    ps.EmbedImage.Image.Save(string.Format(@"Slide\Images{0}.png", i));
                    i++;
                }
            }
        }
    }
}

Imports Spire.Presentation

Namespace ExtractImagesFromSlide
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Presentation class
            Dim ppt As Presentation = New Presentation()
            'Load a PowerPoint presentation
            ppt.LoadFromFile("Template4.pptx")

            'Get the first slide
            Dim slide As ISlide = ppt.Slides(0)

            Dim i = 0
            'Iterate through all shapes on the first slide
            For Each s As IShape In slide.Shapes
                'Check if the shape is of SlidePicture type
                If TypeOf s Is SlidePicture Then
                    'Extract the image
                    Dim ps As SlidePicture = TryCast(s, SlidePicture)
                    ps.PictureFill.Picture.EmbedImage.Image.Save(String.Format("Slide\Images{0}.png", i))
                    i += 1
                End If
                'Check if the shape is of PictureShape type
                If TypeOf s Is PictureShape Then
                    'Extract the image
                    Dim ps As PictureShape = TryCast(s, PictureShape)
                    ps.EmbedImage.Image.Save(String.Format("Slide\Images{0}.png", i))
                    i += 1
                End If
            Next
        End Sub
    End Class
End Namespace