Change the constructor of PixelTypeInfo and ImageMetadata from internal to public so that a user can implement IImageInfo

src/ImageSharp/Formats/PixelTypeInfo.cs

@@ -15,8 +15,17 @@ public class PixelTypeInfo
         /// Initializes a new instance of the <see cref="PixelTypeInfo"/> class.
         /// </summary>
         /// <param name="bitsPerPixel">Color depth, in number of bits per pixel.</param>
-        /// <param name="alpha">Tthe pixel alpha transparency behavior.</param>
-        internal PixelTypeInfo(int bitsPerPixel, PixelAlphaRepresentation? alpha = null)
+        public PixelTypeInfo(int bitsPerPixel)
+        {
+            this.BitsPerPixel = bitsPerPixel;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PixelTypeInfo"/> class.
+        /// </summary>
+        /// <param name="bitsPerPixel">Color depth, in number of bits per pixel.</param>
+        /// <param name="alpha">The pixel alpha transparency behavior.</param>
+        public PixelTypeInfo(int bitsPerPixel, PixelAlphaRepresentation alpha)
         {
             this.BitsPerPixel = bitsPerPixel;
             this.AlphaRepresentation = alpha;

src/ImageSharp/Metadata/ImageMetadata.cs

@@ -40,7 +40,7 @@ public sealed class ImageMetadata : IDeepCloneable<ImageMetadata>
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageMetadata"/> class.
         /// </summary>
-        internal ImageMetadata()
+        public ImageMetadata()
         {
             this.horizontalResolution = DefaultHorizontalResolution;
             this.verticalResolution = DefaultVerticalResolution;