diff --git a/src/ImageSharp/Formats/Jxl/Metadata/InlineArrays.cs b/src/ImageSharp/Formats/Jxl/InlineArrays.cs
similarity index 92%
rename from src/ImageSharp/Formats/Jxl/Metadata/InlineArrays.cs
rename to src/ImageSharp/Formats/Jxl/InlineArrays.cs
index f1f9d3037b..e89b924681 100644
--- a/src/ImageSharp/Formats/Jxl/Metadata/InlineArrays.cs
+++ b/src/ImageSharp/Formats/Jxl/InlineArrays.cs
@@ -5,7 +5,7 @@ using System.Runtime.CompilerServices;
 
 #pragma warning disable SA1649 // File name should match first type name
 
-namespace SixLabors.ImageSharp.Formats.Jxl.Metadata;
+namespace SixLabors.ImageSharp.Formats.Jxl;
 
 [InlineArray(3)]
 internal struct InlineArray3<T>
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlQuantizedSpline.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlQuantizedSpline.cs
new file mode 100644
index 0000000000..c4e5bd2143
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlQuantizedSpline.cs
@@ -0,0 +1,26 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal sealed class JxlQuantizedSpline
+{
+    public JxlQuantizedSpline()
+    {
+        for (int i = 0; i < 3; i++)
+        {
+            this.ColorDct[i] = new int[32];
+        }
+    }
+
+    public Dictionary<long, long> ControlPoints { get; set; } = [];
+
+    // NOTE: Do not use Configuration.MemoryAllocator.Allocate2D. This is
+    // a 3x32 array, and renting memory introduces too much overhead for
+    // 384 bytes of memory.
+    // Additionally, prefer jagged arrays instead of multidimensional arrays
+    // for performance.
+    public int[][] ColorDct { get; set; } = new int[3][];
+
+    public int[] SigmaDct { get; set; } = new int[32];
+}
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlSpline.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlSpline.cs
new file mode 100644
index 0000000000..21dcf7dd3a
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlSpline.cs
@@ -0,0 +1,13 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal sealed class JxlSpline
+{
+    public List<PointF> ControlPoints { get; set; } = [];
+
+    public JxlDct32[] ColorDct { get; set; } = [];
+
+    public JxlDct32 SigmaDct { get; set; }
+}
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlSplineDataView.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineDataView.cs
new file mode 100644
index 0000000000..1884b85c68
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineDataView.cs
@@ -0,0 +1,13 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal sealed class JxlSplineDataView
+{
+    public List<JxlQuantizedSpline> Splines { get; set; } = [];
+
+    public List<PointF> StartingPoints { get; set; } = [];
+
+    public bool HasAny => this.Splines.Count > 0;
+}
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlSplineEntropyContext.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineEntropyContext.cs
new file mode 100644
index 0000000000..1daa61bf76
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineEntropyContext.cs
@@ -0,0 +1,15 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal enum JxlSplineEntropyContext
+{
+    QuantizationAdjustment,
+    StartingPosition,
+    NumSplines,
+    NumControlPoints,
+    ControlPoints,
+    Dct,
+    NumSplineContexts
+}
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegment.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegment.cs
new file mode 100644
index 0000000000..7e8bef1beb
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegment.cs
@@ -0,0 +1,17 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal struct JxlSplineSegment
+{
+    public PointF Center { get; set; }
+
+    public float MaximumDistance { get; set; }
+
+    public float InverseSigma { get; set; }
+
+    public float SigmaOver4TimesIntensity { get; set; }
+
+    public InlineArray3<float> Color { get; set; }
+}
diff --git a/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegmentSpan.cs b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegmentSpan.cs
new file mode 100644
index 0000000000..b4bd52af4f
--- /dev/null
+++ b/src/ImageSharp/Formats/Jxl/Splines/JxlSplineSegmentSpan.cs
@@ -0,0 +1,11 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jxl.Splines;
+
+internal struct JxlSplineSegmentSpan(int startInclusive, int endInclusive)
+{
+    public int StartInclusive { get; set; } = startInclusive;
+
+    public int EndInclusive { get; set; } = endInclusive;
+}