Dynapik offers a free online tool to change image types - no need to download anything. It's quick and easy to use. You can change your HDR images to JNG format. This tool works for both professionals and casual users. Convert your images to JNG in seconds.
Radiance HDR
The pioneering high dynamic range format for lighting simulation.
The Radiance HDR format (often called RGBE) is a raster image format designed for storing high dynamic range (HDR) data. Rather than standard 8-bit integers, it uses a specialized encoding where pixel colors are stored as Red, Green, and Blue mantissas sharing a single common Exponent (RGBE). This allows it to represent a vast range of luminance values, from direct sunlight to deep shadows, in a relatively compact 32-bit-per-pixel format.
The .hdr format consists of a human-readable header containing variables like exposure and gamma, followed by binary pixel data. The pixel data typically uses the 'Radiance RGBE' encoding. Each pixel is 4 bytes: one byte each for Red, Green, and Blue, and one shared Exponent byte. This 'shared exponent' scheme is efficient but introduces some limitations—if one channel is very bright and another is very dark in the same pixel, color precision can be lost (color banding).
Developed by Greg Ward in the late 1980s for the Radiance lighting simulation system. It was one of the first formats to enable practical HDR storage and became a de facto standard in the CGI industry for Image-Based Lighting (IBL).
JPEG Network Graphics
JPEG compression with PNG transparency.
JNG (JPEG Network Graphics) is a sub-format of the MNG animation format. It was designed to combine the high compression of JPEG with the alpha transparency features of PNG, something that standard JPEG lacks. It essentially wraps a JPEG stream and a mask channel in a chunk-based container.
A JNG file structure mimics PNG. It uses a 8-byte signature and chunks. The image data is split into a color chunk (JDAT) which contains JPEG data, and an alpha chunk (IDAT) which contains PNG-compressed alpha mask. This allows for 'lossy color, lossless alpha' images, which is very space-efficient for photographic sprites.
Created by the PNG Development Group around 2001 as part of the MNG (Multiple-image Network Graphics) project. It failed to gain traction as MNG was rejected by Mozilla and Chromium in favor of APNG and later WebP.
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