image / image-decode-jpegBuilt by daveRuns on Liberas

Decode JPEG

Decodes baseline and progressive 8-bit JPEG, grayscale or YCbCr (any chroma subsampling), to RGBA8 with alpha 255. Output must match the reference bit for bit: it uses libjpeg's integer "islow" IDCT, triangle (fancy) chroma upsampling off, and the standard fixed-point YCbCr→RGB conversion, as jpeg-decoder 0.3 implements them. CMYK, 12-bit, lossless and arithmetic-coded files are errors. At most 16,777,216 pixels; larger images are an error.

image-decode-jpeg.wit

package root:component;

world root {
  import liberas:image/types@0.1.0;

  export liberas:image/decode@0.1.0;
}
package liberas:image@0.1.0 {
  interface types {
    record image {
      width: u32,
      height: u32,
      pixels: list<u8>,
    }
  }
  interface decode {
    use types.{image};

    decode: func(data: list<u8>) -> result<image, string>;
  }
}

image-decode-jpeg.cases.json

[
  {
    "args": {
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    }
  },
  {
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    }
  },
  {
    "args": {
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    }
  },
  {
    "args": {
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    }
  },
  {
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    }
  },
  {
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    }
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  {
    "args": {
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    }
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    }
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  {
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]

Verification

Outputs must match the private reference implementation bit for bit.
Cases are the spec's 12 vectors plus ones generated from the interface's types: edge values and random ones seeded by your component's hash.
Components may not import anything but the interfaces of the specs they depend on: no files, no network, no clock.
Runs on Liberas: the component never leaves the platform, and every call is metered on the ledger.
A remote call may execute up to 4,000,000,000 instructions.
Already built: a component that passes and uses at most 0.9× the current one's fuel on the same cases replaces it, and earns the spec's shares in proportion to the saving.
Found an input where the current component disagrees with the spec? Submit it as a case (API or `liberas case`): it joins the vectors for good and earns 10% of the spec's shares. A component that then passes replaces the broken one for 25%.