Options reference

Every field of HyperCompressOptions, in every surface that accepts options: the options object in the Node and WebAssembly SDKs, --set key=value in the CLI, and the options JSON parameter of the HTTP API. Pass any subset; unspecified fields come from the selected preset.

This page is generated from the SDK source, so it cannot drift from the code.

Images

Option	Type	Default	What it does
`imageQuality`	number 5 to 100	80	JPEG quality for re-encoded images. Lower is smaller with more visible artefacts. Below about 20 the artefacts are obvious, which is why no preset goes there, but a size target can.
`maxDpi`	number 0 to 600	150	Images above this resolution are resampled down. 0 leaves resolution alone.
`forceDownsample`	boolean	false	Resample even when the image is only slightly above the limit.
`lossless`	boolean	false	Turns off quality, resolution and every other lossy image step.
`grayscale`	boolean	false	Convert images to grayscale.
`reduceColor`	boolean	false	Reduce colour complexity where it does not change appearance.
`clipImages`	boolean	false	Crop image data hidden outside the visible clip region.
`preferJpx`	boolean	false	Let JPEG 2000 compete with JPEG per image and keep the smaller one.
`removeAlternates`	boolean	false	Drop alternate image versions.
`flattenIcc`	boolean	false	Flatten ICC colour profiles.

Rasterization

For image-only documents such as scans and print-to-PDF output. The engine refuses to rasterize when any page contains text, including an invisible OCR layer, so this cannot destroy searchable text; the skip is reported in the result's warnings. Rasterization is also disabled while preserving PDF/A conformance.

Option	Type	Default	What it does
`rasterizePages`	boolean	false	Replace each page with a single rendered image. Shrinks vector-heavy pages dramatically.
`rasterizeDpi`	number 36 to 600	150	Render resolution. Higher keeps more detail.
`rasterizeQuality`	number 1 to 100	50	JPEG quality for the rasterized pages.
`rasterizeText`	boolean	false	Rasterize pages even when the document has a text layer. Text stops being selectable and searchable, and links stop working. Needs rasterizePages.

Fonts

Option	Type	Default	What it does
`subsetFonts`	boolean	false	Keep only the glyphs the document uses. Lossless by definition.
`removeStandardFonts`	boolean	false	Unembed the standard 14 PDF fonts; viewers supply them.
`unembedAliasedFonts`	boolean	false	Unembed metric-compatible clones of the standard fonts. Arial, Times New Roman and Courier New map to the built-in equivalents. Only applied when safe.
`mergeFonts`	boolean	false	Merge duplicate font programs and dictionaries.

Structure and interactivity

Option	Type	Default	What it does
`removeAnnots`	boolean	false	Remove comments and other annotations.
`flattenForms`	boolean	false	Flatten form fields into page content. Form fields stop being fillable.
`flattenLinks`	boolean	false	Flatten link annotations. Links stop being clickable.
`removeSignatures`	boolean	false	Remove digital signatures so a signed document can be compressed instead of returned untouched. The visible signature stays on the page, but the file is no longer signed and can be signed again.
`removeStructTree`	boolean	false	Drop the structure tree. Removes tagging, which screen readers rely on.
`removeThreads`	boolean	false	Remove article threads.

Metadata and cleanup

Option	Type	Default	What it does
`removeThumbnails`	boolean	false	Remove embedded page thumbnails.
`removeAppData`	boolean	false	Remove application-private data and piece info.
`removeSpiderInfo`	boolean	false	Remove web capture information.
`removeOutputIntents`	boolean	false	Remove output intents.

Output format

Option	Type	Default	What it does
`preserveConformance`	boolean	false	Keep a PDF/A document conformant. Disables every step that would break the standard, including Brotli and rasterization; anything dropped is reported in warnings.
`brotli`	boolean	false	PDF 2.0 Brotli stream compression. Smaller files, but the reader must support it (MuPDF 1.26+, Ghostscript 10.06+, Firefox). Off while preserving PDF/A.

Preset values

What each preset sets, field by field. A preset is just a complete options object; start from one and override any field.

Option	low	medium	high	lossless
`imageQuality`	80	50	20	100
`maxDpi`	200	150	72	0
`forceDownsample`	false	false	false	false
`lossless`	false	false	false	true
`grayscale`	false	false	false	false
`reduceColor`	true	true	true	true
`clipImages`	false	true	true	false
`preferJpx`	true	true	true	false
`removeAlternates`	false	false	true	false
`flattenIcc`	true	true	true	false
`rasterizePages`	false	false	false	false
`rasterizeDpi`	150	150	150	150
`rasterizeQuality`	50	50	50	50
`rasterizeText`	false	false	false	false
`subsetFonts`	true	true	true	true
`removeStandardFonts`	false	false	true	false
`unembedAliasedFonts`	false	false	true	false
`mergeFonts`	true	true	true	true
`removeAnnots`	false	false	false	false
`flattenForms`	false	false	false	false
`flattenLinks`	false	false	false	false
`removeSignatures`	false	false	false	false
`removeStructTree`	false	false	false	false
`removeThreads`	false	false	true	false
`removeThumbnails`	true	true	true	true
`removeAppData`	true	true	true	true
`removeSpiderInfo`	false	false	true	false
`removeOutputIntents`	false	false	false	false
`preserveConformance`	false	false	false	false
`brotli`	false	false	false	false

Options reference ​

Images ​

Rasterization ​

Fonts ​

Structure and interactivity ​

Metadata and cleanup ​

Output format ​

Preset values ​