This new alpha build has a quality of life improvement for the Move tools, support for CICP metadata, and good quality HDR->SDR tone mapping when opening HDR images with supported file types (including plugins).

You can read more about the CICP and HDR tone mapping support at https://x.com/rickbrewPDN/status/2072357433390047252 or https://bsky.app/profile/rickbrew.bsky.social/post/3mplx7ujotk2a

You can read more about 5.2 and what it includes by reading the release notes for the first alpha.

Change Log

Changes since 5.2 Alpha (build 9650):

• Changed: The Move Selection and Move Selected Pixels tools will now behave more intuitively when using constrained resizing (when holding shift). The aspect ratio that was used for a constrained resize used to be “locked in” when the selection was first drawn. The aspect ratio is now picked up when you start a constrained resize, and remembered until a non-constrained resize is performed.
• Added CICP metadata and color management support to the imaging framework 
  • See the CicpColorSpace struct in the PaintDotNet.Imaging namespace.
  • It has a CanColorTransformFrom property, indicating that it can be used as the source color space for the IImagingFactory.CreateColorTransformedBitmap or IBitmapSource.CreateColorTransformer extension methods.
  • It also has a CanCreateColorContext property that indicates when it is possible to create an IColorContext directly (ICC profiles can’t be generated for all CICP combinations) with the IImagingFactory.CreateColorContext(CicpColorSpace) extension method.
  • These can then be used by a FileType to provide a compatible image (“document”). Paint.NET’s color management is based on ICC color profiles, and some CICP color spaces (those involving PQ or HLG) cannot be expressed as an ICC color profile. Those images can, however, be transformed to an ICC-compatible color space with the aforementioned extension methods.
• Added HDR support to the new FileType plugin system
  • An image is tagged as HDR at load time via the IFileTypeDocument.Metadata.Hdr metadata section. Set IsHdrDocument to true, and optionally specify luminance data. The pixel format must be floating point (PixelFormats.Rgba64Half or PixelFormats.Rgba128Float), and the color context must be linearized.
  • Paint.NET does not yet support HDR editing, so it will convert the image to SDR with appropriate, high quality tone mapping.
• Added CICP support for AVIF, JPEG XL, and PNG.
• Added HDR tone mapping support for AVIF, HEIC, JPEG XL, JPEG XR, and PNG. If the image file being opened is HDR then it will be converted to SDR in an appropriate manner. Eventually Paint.NET will support HDR editing, this conversion process will go away, and the FileType plugins won’t even need to be updated.
• Added Rgb64, Rgb64Half, and Rgb128Float pixel formats for the imaging framework.
• Added a /disableCompositionSwapChain command-line parameter. This disables the use of Windows.UI.Composition, and should enable easier progress on the WINE effort.
• Fixed: When right-clicking on an image tab at the top, and then clicking on Open Containing Folder, two Explorer windows were being opened.
• Added a note in the installer about the new website address (https://www.paint.net). You can read more about it here: https://x.com/rickbrewPDN/status/2060397901650825238 or https://bsky.app/profile/rickbrew.bsky.social/post/3mmz73u6lzs2t

Download and Install

This build is available via the built-in updater as long as you have opted-in to pre-release updates. From within Settings -> Updates, enable “Also check for pre-release (beta) versions of paint.net” and then click on the Check Now button. You can also use the links below to download an offline installer or portable ZIP.

You can also download the installer here (for any supported CPU and OS), which is also where you can find downloads for offline installers, portable ZIPs, and deployable MSIs.