modern-pdf-lib

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modern-pdf-lib / RecompressOptions

Interface: RecompressOptions

Defined in: src/assets/image/imageOptimize.ts:62

Options for image recompression.

Extended by

• ImageOptimizeOptions

Properties

chromaSubsampling?

readonly optional chromaSubsampling: ChromaSubsampling

Defined in: src/assets/image/imageOptimize.ts:108

Chroma subsampling mode. Only used when format is 'jpeg'.

• '4:4:4': No subsampling — best color fidelity, largest file.
• '4:2:2': Horizontal subsampling — good balance.
• '4:2:0': Both horizontal and vertical — smallest file.

Requires the JPEG WASM module to be initialized.

Default: '4:2:0'.

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compressionLevel?

readonly optional compressionLevel: 1 | 6 | 3 | 2 | 4 | 5 | 7 | 8 | 9

Defined in: src/assets/image/imageOptimize.ts:84

Deflate compression level (1–9). Only used when format is 'deflate'. Higher values produce smaller files but take longer.

Default: 6.

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format?

readonly optional format: "jpeg" | "deflate"

Defined in: src/assets/image/imageOptimize.ts:70

Output format.

• 'jpeg': JPEG compression (lossy, good for photographs)
• 'deflate': Deflate/zlib compression (lossless, used in PDF FlateDecode)

Default: 'deflate'.

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progressive?

readonly optional progressive: boolean

Defined in: src/assets/image/imageOptimize.ts:96

Encode as progressive JPEG. Only used when format is 'jpeg'.

Progressive JPEGs render in multiple passes (low-res → full-res) which improves perceived loading speed on slow connections. They are also often slightly smaller than baseline JPEGs.

Requires the JPEG WASM module to be initialized.

Default: false.

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quality?

readonly optional quality: number

Defined in: src/assets/image/imageOptimize.ts:77

JPEG quality (1–100). Only used when format is 'jpeg'. Higher values produce larger files with better quality.

Default: 85.