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 PNG images to J2K format. This tool works for both professionals and casual users. Convert your images to J2K in seconds.
PNG (Portable Network Graphics)
The web's standard for lossless images with transparency, designed as a patent-free replacement for GIF.
PNG (Portable Network Graphics) emerged in 1996 as a direct response to the patent issues surrounding the GIF format's LZW compression algorithm. Developed by an informal working group and later standardized by the W3C, PNG was engineered from the ground up to be completely patent-free while offering superior technical capabilities. Unlike JPEG, which sacrifices image data for smaller files, PNG preserves every pixel exactly as captured or created. This lossless nature makes PNG the definitive choice for images where precision matters—screenshots, digital artwork, logos, and any graphic with text or sharp edges. The format's support for full alpha transparency (256 levels of opacity per pixel) revolutionized web design, enabling smooth drop shadows, gradient fades, and complex overlays that were impossible with GIF's binary transparency. Today, PNG is universally supported across all browsers, operating systems, and image editing software. While newer formats like WebP offer better compression, PNG remains the standard for lossless web graphics due to its unmatched compatibility and reliability.
PNG uses DEFLATE compression, the same algorithm powering ZIP files and gzip. This two-stage process first applies filtering to exploit the correlation between adjacent pixels, then compresses the filtered data using LZ77 followed by Huffman coding. The result is lossless compression that typically achieves 10-30% size reduction compared to raw pixel data, with some images compressing significantly more. The format supports multiple color types: grayscale (1-16 bits), indexed color with up to 256 palette entries, truecolor RGB (24 or 48 bits), and each with optional alpha channels. PNG's chunk-based architecture allows for extensibility—the file consists of a signature followed by typed chunks containing image data, metadata, and optional features like gamma correction and color profiles. PNG offers two interlacing modes: no interlacing (smaller file size) or Adam7 interlacing, which progressively renders the image in seven passes. While interlacing increases file size by approximately 10%, it provides a better user experience on slow connections by showing a low-resolution preview almost immediately.
PNG development began in January 1995 when Unisys announced it would enforce patents on GIF's LZW compression. Within weeks, an informal group on comp.graphics formed to create a replacement. Thomas Boutell published the first PNG specification draft in March 1995, and after extensive community input, PNG 1.0 became an official W3C Recommendation on October 1, 1996. The format underwent one major revision: PNG 1.2 in 1999 added the iCCP chunk for ICC color profiles and the sRGB chunk for standard color space indication. PNG became an ISO/IEC standard (15948) in 2003, cementing its position as a core web technology. The related APNG (Animated PNG) extension emerged in 2004 but remains unofficial, though it's now supported by all major browsers.
JPEG 2000 Code Stream
Another extension for the raw JPEG 2000 code stream.
J2K is functionality identical to J2C. It represents a raw JPEG 2000 codestream without the JP2 file format wrapper. It is often used interchangeably with J2C and JPC in technical contexts.
Like J2C, a J2K file contains the wavelet-compressed image data (SOP/EPH markers). It relies on the decoder to interpret the stream markers correctly without the 'boxes' found in the JP2 container format.
Part of the ISO/IEC 15444-1 standard. The multiple extensions (.j2k, .j2c, .jpc) arose from different vendor implementations early in the standard's life.
Experience lightning-fast image conversions with our advanced algorithms. No more waiting for your files to be uploaded before processing.
Enjoy unlimited image conversions without any hidden fees. Our service is completely free to use, with no limitations on file size or quantity.
Convert images files between over 20 formats. We support popular formats like PNG, JPG, WebP, HEIC and more.
Use Dynapik on any device with a modern browser. We support all major platforms such as Windows, macOS, Linux, Android, and iOS.
Ensure high fidelity in your conversions. Our professional-grade output is ideal for designers, marketers, and content creators.
Your files are safe with us. We focus on your privacy and security with advanced encryption and local processing.