KnifeLemon · Nov 12, 2026 · Nov 11, 2026 · Nov 11, 2026 · Nov 11, 2026 · Nov 11, 2026
@@ -41,6 +41,8 @@
     <!-- 5.3+ requires SkiaSharp 4, which conflicts with Avalonia 12.1 (SkiaSharp 3.119). -->
     <PackageVersion Include="PDFtoImage" Version="5.2.1" />
     <PackageVersion Include="Unhwp" Version="0.13.0" />
+    <!-- Reads the .NET binary serialization inside Paint.NET's .pdn files as data, never instantiating types. -->
+    <PackageVersion Include="System.Formats.Nrbf" Version="10.0.14" />
     <PackageVersion Include="Markdig" Version="1.5.1" />
     <PackageVersion Include="ExcelNumberFormat" Version="1.1.0" />
     <!-- 5.2+ requires SkiaSharp 4 (see PDFtoImage above); 5.1.1 uses SkiaSharp 3.119 and HarfBuzzSharp 8.3 like Avalonia. -->

@@ -166,7 +166,7 @@ To undo it, remove the entries in Windows Security → App & browser control →
 
 | From | To |
 |---|---|
-| **Images**: JPG, PNG, WEBP, AVIF, TIFF, BMP, GIF, APNG, ICO, ICNS, JPEG XL, JPEG 2000, PSD/PSB, TGA, PPM, HEIC, QOI, DDS, PCX, MNG, CUR, …;<br>GIMP XCF, camera RAW (CR2, CR3, NEF, ARW, DNG, …), DICOM, OpenEXR, HDR, FITS, JPEG XR (Windows), iPhone Live Photo (LIVP), animated cursor (ANI) read | any of these (HEIC⁵), PDF, SVG (traced), resized, grayscale;<br>Live/Motion Photos (iPhone, Android) → their video (MP4, MOV⁵), and a video → Live Photo (iPhone) or Motion Photo (Android)⁵, experimental |
+| **Images**: JPG, PNG, WEBP, AVIF, TIFF, BMP, GIF, APNG, ICO, ICNS, JPEG XL, JPEG 2000, PSD/PSB, TGA, PPM, HEIC, QOI, DDS, PCX, MNG, CUR, …;<br>GIMP XCF, camera RAW (CR2, CR3, NEF, ARW, DNG, …), DICOM, OpenEXR, HDR, FITS, JPEG XR (Windows), iPhone Live Photo (LIVP), Paint.NET PDN (↔ PSD with its layers), animated cursor (ANI) read | any of these (HEIC⁵), Paint.NET PDN, PDF, SVG (traced), resized, grayscale;<br>Live/Motion Photos (iPhone, Android) → their video (MP4, MOV⁵), and a video → Live Photo (iPhone) or Motion Photo (Android)⁵, experimental |
 | **Vector**: SVG, SVGZ, EMF, WMF, AI<br>EPS, PS¹<br>CDR, VSD, CGM, ODG, FODG² | PDF (vector), PNG and other images,<br>SVG ↔ SVGZ, SVG → DXF/DWG, PDF → EPS/PS¹, SVG → EMF, WMF, ODG² |
 | **PDF** | DOCX, HWPX, TXT, PNG, JPG, TIFF, CBZ, PPTX (a picture of each page), SVG²;<br>merge (in an order you choose first), split, page ranges, compress (smaller PDFs) |
 | **Documents**: DOCX, DOCM, DOTX, EML, Outlook MSG;<br>OFD (Chinese e-invoices, official documents) read<br>DOC, ODT, FODT, OTT, RTF, WPS, WPD, Pages, ClarisWorks, MacWrite, T602, …² | PDF, DOCX, HWPX, EPUB, TXT, HTML;<br>MSG → EML<br>ODT, FODT, OTT² |

@@ -41,6 +41,7 @@ Each component remains under its own license.
 | AngleSharp | MIT | https://github.com/AngleSharp/AngleSharp |
 | pypandoc-hwpx (Pandoc AST mapping and package layout in `Filee.Engines/Hwp/Hwpx`, incl. the `blank.hwpx` reference document) | MIT, Copyright (c) 2024 pypandoc-hwpx Contributors | https://github.com/msjang/pypandoc-hwpx |
 | Microsoft.Extensions.* | MIT | https://github.com/dotnet/runtime |
+| System.Formats.Nrbf (reads Paint.NET .pdn files) | MIT | https://github.com/dotnet/runtime |
 | cu2qu (fontTools): the cubic-to-quadratic approach followed by `Filee.Engines/Fonts/Cff/CubicToQuadratic.cs` | Apache-2.0, Copyright 2016 Google Inc. | https://github.com/fonttools/fonttools |
 
 libuiohook (the native input hook inside SharpHook) is the fork https://github.com/TolikPylypchuk/libuiohook, licensed

@@ -5,7 +5,7 @@ Filee chooses engines automatically. Settings → *Engines* shows their status,
 
 | Engine | How it gets there | Handles |
 |---|---|---|
-| ImageMagick (Magick.NET) | built in (library) | JPG, PNG, WEBP, TIFF, BMP, GIF, ICO, AVIF, JPEG XL, JPEG 2000, PSD/PSB, TGA, PPM, MNG, QOI, DDS, PCX, CUR, XPM, XBM, WBMP, PAM, PFM, SGI, Sun Raster, MIFF ↔ each other, and **APNG** (Filee's own reader and writer); HEIC (written with FFmpeg), XCF, camera RAW (LibRaw), DICOM (uncompressed ones by Filee's own reader), **FITS** (Filee's own reader; TIFF at the file's own depth by Filee's own writer), Photo CD, OpenEXR, Radiance HDR, EMF/WMF (Windows), the photo of an iPhone LIVP, the merged picture of a Krita KRA, the icon of a Windows program or library (EXE, DLL) and a Windows **animated cursor** (ANI, Filee's own reader) read |
+| ImageMagick (Magick.NET) | built in (library) | JPG, PNG, WEBP, TIFF, BMP, GIF, ICO, AVIF, JPEG XL, JPEG 2000, PSD/PSB, TGA, PPM, MNG, QOI, DDS, PCX, CUR, XPM, XBM, WBMP, PAM, PFM, SGI, Sun Raster, MIFF ↔ each other, and **APNG** (Filee's own reader and writer); HEIC (written with FFmpeg), XCF, camera RAW (LibRaw), DICOM (uncompressed ones by Filee's own reader), **FITS** (Filee's own reader; TIFF at the file's own depth by Filee's own writer), Photo CD, OpenEXR, Radiance HDR, EMF/WMF (Windows), the photo of an iPhone LIVP, the merged picture of a Krita KRA, a **Paint.NET PDN** (Filee's own reader and writer: layers merged as Paint.NET shows them, or kept between PDN and PSD/PSB), the icon of a Windows program or library (EXE, DLL) and a Windows **animated cursor** (ANI, Filee's own reader) read |
 | Windows Imaging Component | part of Windows (Windows only) | **JPEG XR** (JXR, WDP, HDP; HDR screenshots of Windows) → the images ImageMagick writes, and PDF, ICNS, HEIC and SVG through PNG; HDR tone-mapped to SDR |
 | Vector graphics | built in (Svg.Skia, SkiaSharp, ACadSharp) | **SVG/SVGZ → PDF (vector) and images**, SVG ↔ SVGZ, **SVG → DXF** (→ DWG with the CAD engine), **raster images → SVG (tracing)**, PDF-compatible AI → PDF, **HP-GL / HP-GL/2 plot files (PLT) → SVG**, PDF and images (pen moves, packed PE polylines, arcs and filled polygons; text labels are not drawn), **Tajima DST embroidery → SVG** (stitches as lines, a palette colour per thread; → PNG, JPG, PDF from there) |
 | ICNS | built in | images → ICNS (16–1024 px), ICNS → images |
@@ -346,6 +346,20 @@ in it also builds the package (artifact `windows-arm64-package`).
   without one gives a clear error. Krita's backup of the previous save, `name.kra~`, is the same file and is read the
   same way; its output is named `name.png`. Watch folders skip it (and any name ending in `~`), as it is written next
   to the drawing on every save.
+- **PDN** (Paint.NET's own file) is read by Filee itself (`PaintNet`): an XML header, the document in .NET binary
+  serialization, read as plain data with System.Formats.Nrbf (no type it names is ever created), then each layer's BGRA
+  pixels in gzip-compressed chunks. For PNG, JPG and every other target the visible layers are merged with Paint.NET's
+  own blend formulas (all 14 modes, layer opacity), so the picture looks as it does in Paint.NET. To **PSD / PSB** the
+  layers are kept, for Photoshop, GIMP and Krita: names (also as Unicode, `luni`), opacity, visibility and the blend
+  modes Photoshop shares (Multiply, Additive as Linear Dodge, Color Burn, Color Dodge, Overlay, Difference, Lighten,
+  Darken, Screen; Reflect, Glow, Negation and Xor become Normal), with the merged picture first. ImageMagick's PSD
+  writer stores a layer's visibility in the wrong bit and locks its transparency, so `PaintNet.SetLayerFlags` sets the
+  flags afterwards. A preset that changes the picture (resize, rotate, …) gives one merged picture instead.
+  Filee also **writes** PDN (`PaintNetWriter`), in the shape Paint.NET 4.2 saves and every later version opens (the
+  same records, class metadata and 256 KB gzip chunks, and a thumbnail in the header): any picture becomes one layer
+  named Background, and a **PSD / PSB** keeps its pixel layers, each at its place on the canvas, with its Unicode name,
+  opacity, visibility and the blend modes Paint.NET shares. PDN → PSD → PDN gives back the same layers, pixel for
+  pixel. A PDN is a target only where the Design & print field is on.
 - **EXE / DLL** (a Windows program or library, #1188) is read as its icon, the one Explorer shows: the first icon group
   of its resources, put back together as an `.ico` in memory (`ProgramIcon`, Filee's own reader for 32 and 64-bit PE
   files; only the headers and the icon are read, at most 64 MB, and the file is never loaded or run). To ICO it is

@@ -75,8 +75,8 @@ .. Enum.GetValues<FormatCategory>().Select(category => category.ToString().ToLow
         (FormatGrade.Specialist,
         [
             "jp2", "psd", "psb", "ppm", "icns", "qoi", "dds", "cur", "xpm", "xbm", "pam", "pfm", "miff", "dcm",
-            "exr", "hdr", "fits", "xcf", "kra", "raw", "eps", "ps", "ai", "cdr", "cgm", "plt", "dst", "fodg", "fodt",
-            "fods", "fodp", "rst", "tex", "org", "adoc", "typ", "mediawiki", "dbk", "ipynb", "textile", "man",
+            "exr", "hdr", "fits", "xcf", "kra", "pdn", "raw", "eps", "ps", "ai", "cdr", "cgm", "plt", "dst", "fodg",
+            "fodt", "fods", "fodp", "rst", "tex", "org", "adoc", "typ", "mediawiki", "dbk", "ipynb", "textile", "man",
             "jsonl", "yaml", "toml", "har", "plist", "htmlz", "txtz", "chm", "dv", "mxf", "cavs", "usm", "m4s", "dav", "bik",
             "h265", "h264", "ac3", "caf", "mp2", "dss", "wv", "tta", "w64", "eac3", "ape", "tak", "dsf", "dff",
             "dts", "tar", "tgz", "tbz2", "txz", "tar7z", "tlz", "gz", "bz2", "xz", "lz", "lzma", "jar", "zxp", "mcpack", "mcaddon",
@@ -97,7 +97,7 @@ .. Enum.GetValues<FormatCategory>().Select(category => category.ToString().ToLow
     private static readonly Dictionary<string, FormatField[]> Overlaps = BuildOverlaps(
     [
         // Layout, print, photo post-production, signs and embroidery.
-        (["psd", "psb", "exr", "hdr", "xcf", "kra", "raw", "eps", "ps", "ai", "cdr", "plt", "dst"], ["design"]),
+        (["psd", "psb", "exr", "hdr", "xcf", "kra", "pdn", "raw", "eps", "ps", "ai", "cdr", "plt", "dst"], ["design"]),
         // Game textures and cutscenes, Minecraft packs and modpacks.
         (["dds", "usm", "bik", "mcpack", "mcaddon", "mcworld", "mctemplate", "mrpack"], ["game"]),
         // Medical imaging and astronomy.

@@ -65,6 +65,8 @@ public static class FormatRegistry
         // Krita's own file (#903): a ZIP whose merged picture (mergedimage.png) is read, as Krita shows it. ".kra~" is the
         // backup Krita keeps of the previous save, the same file under another name (#1077).
         new("kra", "Krita (KRA)", FormatCategory.Image, ["kra", "kra~"], Writable: false),
+        // Paint.NET's own file, read and written by Filee: layers merged for other pictures, kept between PDN and PSD.
+        new("pdn", "Paint.NET (PDN)", FormatCategory.Image, ["pdn"]),
         // iPhone Live Photo as one ZIP (iCloud downloads): the photo, or its video with FFmpeg.
         new("livp", "Live Photo (LIVP)", FormatCategory.Image, ["livp"], Writable: false),
         // A Windows program or library (#1188), read as its icon: the picture Explorer shows for the file.

@@ -170,7 +170,7 @@ public static bool IsFlipKeyAllowed(string key, IEnumerable<TriggerGesture> gest
 public sealed class AppSettings
 {
     /// <summary>Current schema version. Increase when the format changes and add a migration.</summary>
-    public const int CurrentSchemaVersion = 85;
+    public const int CurrentSchemaVersion = 86;
 
     public int SchemaVersion { get; set; } = CurrentSchemaVersion;
 

@@ -1131,6 +1131,9 @@ public static bool ApplyToLibrary(int from, List<Preset> presets, List<ToolbarPr
         // v85: Windows animated cursors (.ani, #1365) learn the images donut; custom claims stay put.
         if (from < 85)
             changed |= LearnExtensions(profiles, out _, ["ani"]);
+        // v86: Paint.NET pictures (.pdn) learn the images donut; custom claims stay put.
+        if (from < 86)
+            changed |= LearnExtensions(profiles, out _, ["pdn"]);
         return changed;
     }
 

@@ -18,6 +18,7 @@
     <PackageReference Include="System.Security.Cryptography.Pkcs" />
     <PackageReference Include="PDFtoImage" />
     <PackageReference Include="Unhwp" />
+    <PackageReference Include="System.Formats.Nrbf" />
     <PackageReference Include="Markdig" />
     <PackageReference Include="ExcelNumberFormat" />
     <PackageReference Include="Svg.Skia" />

@@ -92,9 +92,9 @@ public static bool KeepsAnimation(string sourceFormat, string targetFormat) =>
 
     /// <summary>
     /// Packages of a picture and more, of which the picture is read (<see cref="ImageReader"/>): an iPhone LIVP, a Krita
-    /// KRA, the icon of a Windows program or library (<see cref="ProgramIcon"/>).
+    /// KRA, a Paint.NET PDN (<see cref="PaintNet"/>), the icon of a Windows program or library (<see cref="ProgramIcon"/>).
     /// </summary>
-    public static readonly string[] Packages = ["livp", "kra", FormatRegistry.Program];
+    public static readonly string[] Packages = ["livp", "kra", "pdn", FormatRegistry.Program];
 
     /// <summary>
     /// Every format ImageMagick reads as input: the raster formats, the picture of <see cref="Packages"/> and, on
@@ -193,6 +193,7 @@ public static List<IMagickImage<byte>> SelectFrames(MagickImageCollection images
         "jpg" or "jpeg" => 65_500,
         "webp" => 16_383,
         "avif" => 16_384,
+        "pdn" => PaintNetWriter.MaxSide,
         _ => double.PositiveInfinity,
     };
 
@@ -465,6 +466,19 @@ public static List<string> Write(IReadOnlyList<IMagickImage<byte>> frames, strin
         ImageOptions? options = null, string? sourcePath = null, bool animation = false)
     {
         var written = new List<string>();
+        if (targetFormat == "pdn")
+        {
+            // Paint.NET's own file, written by Filee (PaintNetWriter): one picture per file, as one layer.
+            for (var i = 0; i < frames.Count; i++)
+            {
+                var pdn = output.Allocate("pdn", frames.Count > 1 ? $"_p{i + 1}" : null);
+                if (pdn is null)
+                    continue;
+                PaintNetWriter.Write(frames[i], pdn);
+                written.Add(pdn);
+            }
+            return written;
+        }
         var (format, extension) = OutputFormat(targetFormat, options ?? new ImageOptions(), sourcePath);
 
         if (targetFormat == "apng")
@@ -595,11 +609,16 @@ internal static void FitToSize(IMagickImage<byte> image, string path, MagickForm
         }
     }
 
-    /// <summary>Writes one image as <paramref name="targetFormat"/> (APNG through <see cref="Apng"/>).</summary>
+    /// <summary>
+    /// Writes one image as <paramref name="targetFormat"/> (APNG through <see cref="Apng"/>, Paint.NET's PDN through
+    /// <see cref="PaintNetWriter"/>).
+    /// </summary>
     public static void WriteImage(IMagickImage<byte> image, string path, string targetFormat)
     {
         if (targetFormat == "apng")
             Apng.Write([image], path);
+        else if (targetFormat == "pdn")
+            PaintNetWriter.Write(image, path);
         else
             image.Write(path, ToMagickFormat(targetFormat));
     }

@@ -118,7 +118,8 @@ internal static void Join(IReadOnlyList<(string Path, string Format)> inputs, st
             ImageEncoder.ApplyOptions(merged, rest, format);
             cancellationToken.ThrowIfCancellationRequested();
             ImageEncoder.WriteImage(merged, outputPath, format);
-            if (options.MaxSizeMb > 0 || options.MinSizeMb > 0)
+            // A PDN (lossless, written by Filee) isn't fitted, like an animation: the queue refuses one too large.
+            if ((options.MaxSizeMb > 0 || options.MinSizeMb > 0) && format != "pdn")
                 ImageEncoder.FitToSize(merged, outputPath, ImageEncoder.OutputFormat(format, rest).Format, SizeLimit.Bytes(options.MaxSizeMb),
                     SizeLimit.MinimumBytes(options.MinSizeMb), options.MaxSizeKeepsPixels);
             if (format == "cur")

@@ -2,8 +2,8 @@
 // (LibRaw settings), layered PSD/PSB/XCF (one flattened picture instead of one file per layer) and Windows
 // metafiles (rendered at the preset's DPI), APNG (Filee's own reader composes the frames) and uncompressed DICOM
 // (Filee's own reader, as ImageMagick's Q8 build reads only 8-bit DICOM), FITS (Filee's own reader, stretched and
-// debayered as the preset says), the photo of an iPhone LIVP, the merged picture of a Krita KRA and the icon of a Windows
-// program. Used by every engine that takes a raster image as input.
+// debayered as the preset says), the photo of an iPhone LIVP, the merged picture of a Krita KRA, the layers of a Paint.NET
+// PDN merged as Paint.NET shows them and the icon of a Windows program. Used by every engine that takes a raster image as input.
 
 using System.Buffers.Binary;
 using Filee.Core.Formats;
@@ -35,6 +35,8 @@ public static MagickImageCollection Read(string path, string formatId, Preset pr
             return ReadLivePhoto(path, preset);
         if (formatId == "kra")
             return ReadPackaged(Krita.ReadMerged(path), "png", preset);
+        if (formatId == "pdn")
+            return [PaintNet.ReadFlattened(path)];
         if (formatId == FormatRegistry.Program)
             return ReadPackaged(ProgramIcon.Read(path), "ico", preset);
         if (formatId == "fits")

@@ -29,9 +29,13 @@ public sealed class MagickImageConverter : IConverter, ITiffMerger, IImageTransf
     internal Func<(string Ffmpeg, string Ffprobe)?> LocateFfmpeg { get; init; } = FfmpegConverter.Locate;
 
     public IReadOnlyList<ConversionEdge> Edges { get; } =
-        (from source in ImageEncoder.Sources
-         from target in ImageEncoder.Writable
-         select ImageEncoder.Edge(source, target)).ToList();
+    [
+        .. from source in ImageEncoder.Sources
+           from target in ImageEncoder.Writable
+           select ImageEncoder.Edge(source, target),
+        // Paint.NET's own file, written by Filee (PaintNetWriter); a PSD keeps its layers there.
+        .. ImageEncoder.Sources.Where(source => source != "pdn").Select(source => ImageEncoder.Edge(source, "pdn")),
+    ];
 
     public EngineStatus GetStatus() =>
         EngineStatus.Available(MagickNET.ImageMagickVersion,
@@ -77,7 +81,7 @@ public Task MergeAsync(IReadOnlyList<string> inputPaths, string outputPath, File
 
     public bool CanRead(string format) => ImageEncoder.Sources.Contains(format);
 
-    public bool CanWrite(string format) => ImageEncoder.Writable.Contains(format);
+    public bool CanWrite(string format) => format == "pdn" || ImageEncoder.Writable.Contains(format);
 
     /// <summary>"Merge images": the pictures one under another or side by side in one image (<see cref="ImageJoiner"/>).</summary>
     public Task JoinAsync(IReadOnlyList<(string Path, string Format)> inputs, string outputPath, string format,
@@ -97,6 +101,12 @@ public Task<IReadOnlyList<string>> ConvertAsync(ConversionStep step, IProgress<d
             // A program's icon as ICO is the icon itself, with the sizes drawn for it, unless the preset changes it.
             if (step.From == FormatRegistry.Program && step.To == "ico" && ProgramIcon.KeptAsItIs(step.Preset.Image))
                 return ProgramIcon.Save(step, progress);
+            // A Paint.NET file as PSD keeps its layers, unless the preset changes the picture.
+            if (step.From == "pdn" && step.To is "psd" or "psb" && PaintNet.KeepsLayers(step.Preset.Image))
+                return PaintNet.SaveLayered(step, progress, cancellationToken);
+            // A PSD as a Paint.NET file keeps its layers too.
+            if (step.From is "psd" or "psb" && step.To == "pdn" && PaintNet.KeepsLayers(step.Preset.Image))
+                return PaintNetWriter.SaveLayered(step, progress, cancellationToken);
             // Animated PNGs are often saved as .png: read them as APNG, so they stay animated as GIF or WebP. An AVIF is an
             // animation only when it is an image sequence.
             var from = step.From == "png" && Apng.IsAnimated(step.InputPath) ? "apng" : AvifSequence.SourceFormat(step.From, step.InputPath);