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image

Pure-Java codec library: BMP, GIF, JPEG, PNG, WebP (VP8 lossy + VP8L lossless). Animated frames with per-frame timing, disposal, and blend; virtual-thread batch encode; zero-copy PixelBuffer.

Packages

  • dev.simplified.image - ImageData, ImageFormat, ImageFactory (instance facade - fromFile/toFile/fromByteArray/toByteArray plus *s batch variants)
  • .data - StaticImageData, AnimatedImageData, ImageFrame, FrameBlend, FrameDisposal
  • .pixel - PixelBuffer, PixelGraphics, ColorMath, BlendMode, Resample
  • .transform - FrameNormalizer, FitMode
  • .exception - ImageException hierarchy (ImageDecodeException, ImageEncodeException, UnsupportedFormatException)
  • .codec - ImageReader/ImageWriter SPI + ImageReadOptions/ImageWriteOptions
  • .codec.{bmp,gif,jpeg,png} - <Format>ImageReader/<Format>ImageWriter (+ <Format>WriteOptions builders where relevant)
  • .codec.webp - WebPImageReader, WebPImageWriter, WebPWriteOptions, RiffContainer, WebPChunk (+ nested Type enum for FourCC)
  • .codec.webp.lossless - VP8L internals. Public: VP8LEncoder, VP8LDecoder. Package-private: BitReader, BitWriter, HuffmanTree, ColorCache, LZ77, VP8LTransform.
  • .codec.webp.lossy - VP8 internals. Public: VP8Encoder, VP8Decoder. Package-private: BooleanEncoder/BooleanDecoder, DCT, IntraPrediction, Quantizer, Macroblock, VP8Tables, VP8TokenEncoder/VP8TokenDecoder, LoopFilter, RateDistortion.

VP8 encoder state

Keyframe-only, 16x16 intra. All four luma and chroma modes (DC/V/H/TM) with SSE-based mode selection. No B_PRED 4x4 sub-blocks, no inter-frame. Quantizer / token-tree / coefficient probability tables are copied verbatim from libwebp (src/enc/tree_enc.c, src/enc/frame_enc.c, src/enc/quant_enc.c) - they must stay bit-exact or libwebp will reject the bitstream. WebPImageWriter with isLossless(false) is production-ready.

The VP8 decoder handles the full intra-4x4 B_PRED sub-mode tree for reading libwebp-produced files, but also still carries shortcuts (fixed-width 11-bit coefficient reads) from the old sketch encoder era - a spec-compliant decoder rewrite is a future task.

Builders

Write options use fluent builders: WebPWriteOptions.builder().isLossless(bool).withQuality(float).isMultithreaded().withLoopCount(int).build(). Same pattern for GifWriteOptions, JpegWriteOptions, PngWriteOptions.

Build

./gradlew build                                                       # compile + test
./gradlew test                                                        # tests only
./gradlew test --tests dev.simplified.image.codec.webp.lossy.VP8CodecTest

VP8 lossy tests shell out to Python webp package (libwebp bindings) for round-trip validation. Tests abort gracefully via TestAbortedException when Python or the package is missing, rather than failing.

Info

  • Java 21 toolchain (build.gradle.kts)
  • Internal deps: Simplified-Dev collections, utils, reflection (all pulled via JitPack)
  • External deps: Log4j2, Simplified Annotations, JetBrains annotations
  • Tests: JUnit 5 + Hamcrest
  • 60 source classes, 8 test classes