support conversion of pdf format images to png

src/UglyToad.PdfPig/XObjects/XObjectImage.cs

@@ -6,6 +6,7 @@
     using Core;
     using Graphics.Colors;
     using Graphics.Core;
+    using Images.Png;
     using Tokens;
     using Util.JetBrains.Annotations;
 
@@ -107,6 +108,47 @@
             return true;
         }
 
+        /// <inheritdoc />
+        public bool TryGetPng(out byte[] bytes)
+        {
+            bytes = null;
+            if (ColorSpace != Graphics.Colors.ColorSpace.DeviceRGB || !TryGetBytes(out var bytesPure))
+            {
+                return false;
+            }
+
+            try
+            {
+                var builder = PngBuilder.Create(WidthInSamples, HeightInSamples, false);
+
+                var isCorrectlySized = bytesPure.Count == (WidthInSamples * HeightInSamples * (BitsPerComponent / 8) * 3);
+
+                if (!isCorrectlySized)
+                {
+                    return false;
+                }
+
+                var i = 0;
+                for (var y = 0; y < HeightInSamples; y++)
+                {
+                    for (var x = 0; x < WidthInSamples; x++)
+                    {
+                        builder.SetPixel(bytesPure[i++], bytesPure[i++], bytesPure[i++], x, y);
+                    }
+                }
+
+                bytes = builder.Save();
+
+                return true;
+            }
+            catch
+            {
+                // ignored.
+            }
+
+            return false;
+        }
+
         /// <inheritdoc />
         public override string ToString()
         {