How to Work with the Aspose.PSD FOSS Core API in .NET

Aspose.PSD FOSS for .NET loads and inspects PSD/PSB document structure through PsdImage, a subclass of Image. This article covers loading a document, reading its header and image resources, and saving it back to disk.

Step-by-Step Guide

Step 1: Install the Package

git clone https://github.com/aspose-psd-foss/Aspose.PSD-FOSS-for-.NET.git
cd Aspose.PSD-FOSS-for-.NET
dotnet build

Step 2: Import Required Classes

using Aspose.PSD.FileFormats.Psd;

Step 3: Load a PSD/PSB Document

PsdImage.Load opens a document from a file path or a stream:

using var image = PsdImage.Load("input.psd");

Step 4: Inspect the Document Header

PsdImage exposes header fields read from the parsed document: Width, Height, BitsPerChannel, ColorMode (a ColorModes value), and Compression (a CompressionMethod value):

Console.WriteLine($"{image.Width}x{image.Height}, {image.BitsPerChannel} bpc");
Console.WriteLine($"Color mode: {image.ColorMode}");   // e.g. ColorModes.Rgb
Console.WriteLine($"Compression: {image.Compression}"); // e.g. CompressionMethod.RLE
Console.WriteLine($"Flattened: {image.IsFlatten}");

ColorModes values include Bitmap, Grayscale, Indexed, Rgb, and Cmyk, among others (Multichannel, Duotone, Lab). CompressionMethod values are Raw, RLE, ZipWithoutPrediction, and a ZIP-with-prediction variant.

Step 5: Read Image Resource Blocks

ImageResources returns the document’s parsed ResourceBlock entries. Each block exposes ID, Name, and Size:

foreach (var resource in image.ImageResources)
{
    Console.WriteLine($"Resource {resource.ID} \"{resource.Name}\" - {resource.Size} bytes");
}

ImageResources is read-only in this FOSS build — assigning to it throws NotSupportedException (see Known Limitations in the FAQ).

Step 6: Save the Document

image.Save("output.psd");

Common Issues and Fixes

PsdLoadException when loading a file. The input is not a valid PSD/PSB document, or its header failed validation. Confirm the file is a genuine PSD/PSB file before loading.

NotSupportedException when setting ImageResources or GlobalLayerResources. These setters are not supported in this FOSS build. Treat ImageResources as read-only.

ColorMode or Compression prints as a numeric value instead of a name. Cast the property to its enum type explicitly, or use .ToString(), to get the readable name (ColorModes.Rgb, not 3).

Frequently Asked Questions

Can I load a PSD file from a stream instead of a file path?

Yes — PsdImage.Load has an overload that accepts a Stream.

Does `ImageResources` include layer data?

No. ImageResources holds document-level resource blocks (parsed from the PSD image resources section). Layer-level data is read through PsdImage.Layers — see Working with Layers.

Is `PsdImage.Version` the PSD file format version?

No. PsdImage.Version reports an internal Aspose.PSD-compatible API version number (currently 6) — it is unrelated to whether the loaded file is PSD or PSB.