JPEG-LS Windows Imaging Component Codec

This Windows Imaging Component (WIC) codec makes it possible to decode and encode JPEG-LS (.jls) files with Windows applications that can leverage WIC codecs. It makes it possible to view JPEG-LS encoded images in Windows PhotoViewer, Windows Explorer and import JPEG-LS images in Microsoft Office documents.

Introduction

The Windows Imaging Component (WIC) is a built-in codec framework of Windows that makes it possible to create independent native image codecs that can be used by a large set of applications. WIC is implemented using COM technology. Image codecs for many popular formats are already pre-installed on Windows.

Status

This project is the development phase:

• No installer with pre-built binaries is available, manually building and registering is required.

Supported Operation Systems

The JPEG-LS WIC codec supports the following Windows operating systems:

• Windows 11 and 10 (x86, x64, ARM64)
• Windows Server 2022 and 2019 (x86, x64)

Note: on Windows 10 "N" the Media Feature Pack needs to be installed.

Applications that can use the JPEG-LS WIC codec

The following application have been validated to work with the JPEG-LS WIC codec:

• Windows Explorer Thumbnail cache. This functionality allows Windows Explorer to show previews of images.
• Windows Photo Viewer.
  Note: On clean installations of Windows 10 this component is installed but not registered. An Registry file called restore-windows-photo-viewer.reg is provided to restore this functionality. The Registry Editor can be used to add import this .reg file.
• WIC Explorer (sample application from Microsoft). An updated version of this application can be found at https://github.com/vbaderks/WICExplorer
• ZackViewer https://github.com/peirick/ZackViewer. This viewer can also be used to convert from one image encoding format to another.
• Microsoft Office applications like Word, Excel, PowerPoint. These applications can, when the JPEG-LS codec is installed, import JPEG-LS images in their documents.

Windows 10 Microsoft Photos Application not supported

The standard Windows 10 Microsoft Photos application cannot be used at this moment as it is limited to the WIC codecs that are pre-installed on Windows or are provided by Microsoft in the Microsoft Store. Microsoft currently does not make it possible to create WIC codecs that can be uploaded to the Microsoft Store.

16 bit grayscale images may display as only containg black pixels

Windows has full support for the 16 bit grayscale pixel format (GUID_WICPixelFormat16bppGray). It expect however that the full dynamic range (0 .. 65535) is used. To be able to display the image on the screen Windows needs to convert the image internally to 24 bits BRGA. In essence this means that only the high 8 bits are used.
Medical (DICOM) grayscale images are often using more then 256 different values of gray and will therefore need to use 10, 12 or even 16 bits. If the image format is 16 bit but the dynamic range is much smaller, standard Windows viewing software will show these images as a black rectangle.
Medical viewing software should be used to view these kinds of images. Often additional metadata, not stored in the .jls file, is needed for a good display.
The WIC Explorer, see the section above, has also special support to transform the pixels into the correct dynamic range and can be used to view these images.

WIC Codec Identity

The following table provides the codec identification information:

Property
Formal Name	JPEG-LS Format
File Name Extension	.jls
MIME type	image/jls
Specification Support	JPEG-LS (ISO/IEC 14495-1), SPIFF header (ISO/IEC 10918-3)

The following table lists the GUIDs used to identify the native JPEG-LS codec components:

Component	Friendly Name	GUID
Container Format	id::container_format_jpegls	52c25458-282d-4ef4-a69f-021bb2984543
Decoder	id::jpegls_decoder	e57dc18b-019c-47f2-8ed0-bf587be4ff1b
Encoder	id::jpegls_encoder	70a823ea-009f-402f-9bda-e9b8f6332d61

The following table lists the pixel formats that can be decoded:

GUID	Component Count	Bits per Sample
GUID_WICPixelFormat2bppGray	1	2
GUID_WICPixelFormat4bppGray	1	4
GUID_WICPixelFormat8bppGray	1	8
GUID_WICPixelFormat16bppGray	1	16,12,10*
GUID_WICPixelFormat24bppRGB	3	8
GUID_WICPixelFormat48bppRGB	3	16

Note *: monochrome JPEG-LS images with 10 or 12 pixels will be upscaled to 16 to match a defined WIC pixel format.

The following table lists the pixel formats that can be encoded:

GUID	Component Count	Bits per Sample
GUID_WICPixelFormat2bppGray	1	2
GUID_WICPixelFormat4bppGray	1	4
GUID_WICPixelFormat8bppGray	1	8
GUID_WICPixelFormat16bppGray	1	16
GUID_WICPixelFormat24bppBGR**	3	8
GUID_WICPixelFormat24bppRGB	3	8
GUID_WICPixelFormat48bppRGB	3	16

Note **: BGR images will be converted and saved as RGB. JPEG-LS provides no support to set a BGR color space in the SPIFF header.

Build Instructions

1. Clone this repo, use clone --recurse-submodules to ensure the CharLS git submodule is also cloned correctly in your local git repository.
2. Open Visual Studio 2022 17.8.0 or newer and open the jpeg-wic-codec.sln. Batch build all projects.
3. Or use a Developer Command Prompt and run MSBuild in the root of the cloned repository.

Installation

1. Open a command prompt with elevated rights
2. Navigate to folder with the jpegls-wic-codec.dll
3. Execute:

regsvr32 jpegls-wic-codec.dll

Uninstall

1. Open a command prompt with elevated rights
2. Navigate to folder with the jpegls-wic-codec.dll
3. Execute:

regsvr32 -u jpegls-wic-codec.dll