{"record":{"id":"8288b895e697678c","repo":"SixLabors/ImageSharp","slug":"unknown-quantization-table-precision-precision","errorCode":null,"errorMessage":"Unknown Quantization Table precision {precision}.","messagePattern":"Unknown Quantization Table precision (.+?)\\.","errorType":"exception","errorClass":"InvalidImageContentException","httpStatus":null,"severity":"error","filePath":"src/ImageSharp/Formats/Jpeg/JpegThrowHelper.cs","lineNumber":18,"sourceCode":"// Copyright (c) Six Labors.\n// Licensed under the Six Labors Split License.\n\nnamespace SixLabors.ImageSharp.Formats.Jpeg;\n\ninternal static class JpegThrowHelper\n{\n    public static void ThrowNotSupportedException(string errorMessage) => throw new NotSupportedException(errorMessage);\n\n    public static void ThrowInvalidImageContentException(string errorMessage) => throw new InvalidImageContentException(errorMessage);\n\n    public static void ThrowBadMarker(string marker, int length) => throw new InvalidImageContentException($\"Marker {marker} has bad length {length}.\");\n\n    public static void ThrowNotEnoughBytesForMarker(byte marker) => throw new InvalidImageContentException($\"Input stream does not have enough bytes to parse declared contents of the {marker:X2} marker.\");\n\n    public static void ThrowBadQuantizationTableIndex(int index) => throw new InvalidImageContentException($\"Bad Quantization Table index {index}.\");\n\n    public static void ThrowBadQuantizationTablePrecision(int precision) => throw new InvalidImageContentException($\"Unknown Quantization Table precision {precision}.\");\n\n    public static void ThrowBadSampling() => throw new InvalidImageContentException(\"Bad sampling factor.\");\n\n    public static void ThrowBadSampling(int factor) => throw new InvalidImageContentException($\"Bad sampling factor: {factor}\");\n\n    public static void ThrowBadProgressiveScan(int ss, int se, int ah, int al) => throw new InvalidImageContentException($\"Invalid progressive parameters Ss={ss} Se={se} Ah={ah} Al={al}.\");\n\n    public static void ThrowInvalidImageDimensions(int width, int height) => throw new InvalidImageContentException($\"Invalid image dimensions: {width}x{height}.\");\n\n    public static void ThrowDimensionsTooLarge(int width, int height) => throw new ImageFormatException($\"Image is too large to encode at {width}x{height} for JPEG format.\");\n\n    public static void ThrowNotSupportedComponentCount(int componentCount) => throw new NotSupportedException($\"Images with {componentCount} components are not supported.\");\n\n    public static void ThrowNotSupportedColorSpace() => throw new NotSupportedException(\"Image color space could not be deduced.\");\n}\n","sourceCodeStart":1,"sourceCodeEnd":34,"githubUrl":"https://github.com/SixLabors/ImageSharp/blob/59ce6af6fc29027cda277ef62d4d1694a8acce91/src/ImageSharp/Formats/Jpeg/JpegThrowHelper.cs#L1-L34","documentation":"JpegThrowHelper.ThrowBadQuantizationTablePrecision throws InvalidImageContentException when a DQT segment declares a quantization table precision (the value in the message, encoded in the upper nibble of the table's first byte) other than the supported values — the JPEG spec allows 0 (8-bit) and, for 16-bit tables, 1; anything else is invalid.","triggerScenarios":"Decoding a JPEG whose DQT precision nibble is not 0 or 1 — corrupt streams, hand-crafted/fuzzed data, or output from a non-conformant encoder.","commonSituations":"Malformed files from buggy embedded encoders; corrupted transfers; adversarial uploads to public image endpoints.","solutions":["Treat the input as corrupt and re-obtain/re-export the image.","Catch InvalidImageContentException and reject the file in ingestion paths.","Verify the producing encoder conforms to ITU T.81; re-encode with a standard library if not."],"exampleFix":"// before\nusing var image = Image.Load(stream);\n// after\ntry { using var image = Image.Load(stream); }\ncatch (InvalidImageContentException ex)\n{\n    logger.LogWarning(ex, \"Bad DQT precision\");\n}","handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"try\n{\n    using var image = Image.Load(stream);\n}\ncatch (InvalidImageContentException ex) when (ex.Message.Contains(\"Quantization Table precision\"))\n{\n    rejectUpload(\"Unsupported DQT precision\");\n}","preventionTips":["For untrusted uploads, decode in an isolated step and reject on InvalidImageContentException.","Re-encode source images with a standards-compliant encoder before storage.","Log the offending file for corpus analysis if corruption rates rise."],"tags":["jpeg","decoder","corrupt-data","quantization-table"],"backgroundTag":"corrupt-jpeg-data","analyzedSha":"59ce6af6fc29027cda277ef62d4d1694a8acce91","analyzedAt":"2026-09-13T18:34:59.331Z","contentChangedAt":"2026-09-13T18:34:59.331Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}