Parameter Description

OCR Language Codes

The ocrRecognitionLang parameter specifies the OCR recognition language code. The current API uses the original OCR model language codes. Defaults to AUTO (automatic detection).

Code	Language
AUTO	Auto Detect
CHINESE	Simplified Chinese
CHINESE_TRAD	Traditional Chinese
ENGLISH	English
KOREAN	Korean
JAPANESE	Japanese
LATIN	Latin script
DEVANAGARI	Devanagari script
CYRILLIC	Cyrillic script
ARABIC	Arabic script
TAMIL	Tamil
TELUGU	Telugu
KANNADA	Kannada
THAI	Thai
GREEK	Greek
ESLAV	East Slavic languages

Compression Parameters

optimizeFlags specifies which optimization actions to apply when compressing a PDF. When calling the PDF Compression API, you can pass multiple flags. In Try it, enter one flag per line; the request is submitted as a list.

You can also enter a JSON array, for example:

["RMNOTUSE", "RMEPTOBJ", "BCOMPRESSIMAGE"]

Flag	Description
RMNOTUSE	Remove unused objects
RMEPTOBJ	Remove empty objects
RMSPEATTR	Remove special attributes
RMEMBFONT	Remove embedded fonts
RMINVALINK	Remove invalid links
RMINVABK	Remove invalid bookmarks
BCOMPRESSIMAGE	Compress images
RMBK	Remove bookmarks
RMANNOT	Remove annotations
RMFORM	Remove forms
RMMULMEDIA	Remove multimedia content
RMDOCINFO	Remove document information
RMMEDTADATA	Remove metadata
RMOBJDATA	Remove object data
RMFILEATTACHMENT	Remove file attachments
RMEXTERNCROSSREF	Remove external cross-references
RMOTHERAPPDATA	Remove other application data
RMHIDERLAYER	Remove hidden layers
MERGEVISIBLELAYER	Merge visible layers
USEFLATE	Use Flate compression
FLAT_REPLACELZW	Replace LZW compression with Flate
RMUNUSEDTARGET	Remove unused targets
OPTIMIZEPAGECONTENT	Optimize page content
OPTIMIZEPDFFASTWEBVIEW	Optimize for Fast Web View (linearization)
RMFORMCOMMITIMPORTRESETACTION	Remove form submit/import/reset actions
RMJSACTION	Remove JavaScript actions
RMPAGETHUMBNAIL	Remove page thumbnails
RMREPLACEIMAGE	Replace images
RMLABEL	Remove page labels
RMPRINTSETTINGS	Remove print settings
RMSEARCHINDEX	Remove search index

Image Quality

The imageQuality parameter (0-100) controls the lossy nature of JPEG compression, directly affecting image quality and file size. It can be passed as a parameter when calling the PDF Compression API.

Parameter Range	Technical Meaning	Actual Effect
0	Maximum Quantization (Highest Compression)	Severe distortion, resulting in solid color blocks
50	Medium Quantization	Visible quality loss, suitable for web thumbnails
75-80	Default Recommended Value	Good balance (quality/size), suitable for most scenarios
95-100	Minimal Quantization (Near Lossless)	Close to original image quality, but file size increases significantly

Compressed images do not decrease linearly with quality parameters. The size reduction from 90 to 80 is much greater than from 60 to 50. Therefore, when using this parameter, you should choose the highest image quality within an acceptable size range to ensure display quality.

Color Image Quality

colorImageQuality Color image quality parameter (0-100) controls the lossy nature of JPEG compression, directly affecting image quality and file size. This parameter can be controlled when calling the PDF Compression API.

Parameter Range	Technical Meaning	Actual Effect
0	Maximum quantization (highest compression)	Severe distortion, resulting in solid color blocks
50	Medium quantization	Visible quality loss, suitable for web thumbnails
75-80	Default recommended value	Good balance (quality/size), suitable for most scenarios
95-100	Minimum quantization (near lossless)	Close to original image quality, but file size increases significantly

The compressed image does not decrease linearly with the quality parameter. The size reduction from 90 to 80 is much greater than from 60 to 50. Therefore, when using this parameter, you should choose the highest image quality within an acceptable size range to ensure display quality.

uaConfig.language Values

Pass the case-sensitive SDK enum constant name from CPDFUAConfig.UALanguage. If omitted, the value defaults to unspecified.

Enum Value	Description
unspecified	Unspecified language
cs_CZ	Czech (Czech Republic)
de_DE	German (Germany)
en_GB	English (United Kingdom)
en_US	English (United States)
es_ES	Spanish (Spain)
fi_FI	Finnish (Finland)
fr_FR	French (France)
hu_HU	Hungarian (Hungary)
it_IT	Italian (Italy)
ja_JP	Japanese (Japan)
ko_KR	Korean (South Korea)
nl_BE	Dutch (Belgium)
nl_NL	Dutch (Netherlands)
no_NO	Norwegian (Norway)
pl_PL	Polish (Poland)
pt_BR	Portuguese (Brazil)
pt_PT	Portuguese (Portugal)
ru_RU	Russian (Russia)
sk_SK	Slovak (Slovakia)
sv_SE	Swedish (Sweden)
tr_TR	Turkish (Turkey)
zh_CN	Chinese (Mainland China)
zh_HK	Chinese (Hong Kong, China)
zh_MO	Chinese (Macao, China)
zh_TW	Chinese (Taiwan, China)