parser

package
v1.0.1 Latest Latest
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 Go to latest Published: Jun 30, 2026 License: MIT Imports: 6 Imported by: 0

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Index

Constants

View Source 
const (
	// JP2SignatureLength is the length of the JP2 file signature (12 bytes at file start)
	// 0x00 0x00 0x00 0x0C 0x6A 0x50 0x20 0x20 0x0D 0x0A 0x87 0x0A
	JP2SignatureLength = 12

	// BoxTypeSignature is the JP2 signature box type identifier (4-byte ASCII code as uint32)
	BoxTypeSignature   = 0x6A502020 // "jP  "
	BoxTypeFileType    = 0x66747970 // "ftyp" - File type box
	BoxTypeJP2Header   = 0x6A703268 // "jp2h" - JP2 header superbox
	BoxTypeImageHeader = 0x69686472 // "ihdr" - Image header box
	BoxTypeColourSpec  = 0x636F6C72 // "colr" - Colour specification box
	BoxTypeCodestream  = 0x6A703263 // "jp2c" - Contiguous codestream box
	BoxTypePalette     = 0x70636C72 // "pclr" - Palette box
	BoxTypeCompMap     = 0x636D6170 // "cmap" - Component mapping box
	BoxTypeChanDef     = 0x63646566 // "cdef" - Channel definition box
	BoxTypeResolution  = 0x72657320 // "res " - Resolution superbox
	BoxTypeBPC         = 0x62706363 // "bpcc" - Bits per component box
	BoxTypeXML         = 0x786D6C20 // "xml " - XML box
	BoxTypeUUID        = 0x75756964 // "uuid" - UUID box
	BoxTypeUUIDInfo    = 0x75696E66 // "uinf" - UUID info box

	// MarkerSOC is the J2K start of codestream marker
	MarkerSOC = 0xFF4F
	MarkerSOT = 0xFF90 // Start of tile-part
	MarkerSOD = 0xFFD9 // Start of data
	MarkerEOC = 0xFFD9 // End of codestream

	// MaxBoxRecursionDepth is the maximum box recursion depth (safety limit)
	MaxBoxRecursionDepth = 16
	MaxBoxLength         = 1 << 30 // 1 GB max box length
	MaxBoxCount          = 1000    // Maximum boxes to parse
	MaxComponentCount    = 16384   // Max components per JPEG 2000
	MinImageDimension    = 1
	MaxImageDimension    = 65535
)

JP2 file format constants

View Source 
const (
	ColourSpaceSRGB = 16 // sRGB
	ColourSpaceGrey = 17 // Greyscale
	ColourSpaceSYCC = 18 // sYCC
)

ColourSpace enumeration values

View Source 
const (
	BrandJP2 = 0x6A703220 // "jp2 " - JP2 format
	BrandJPX = 0x6A707820 // "jpx " - JPX format
)

Common brand identifiers

Variables

View Source 
var (
	ErrInvalidJP2Signature    = errors.New("invalid JP2 signature")
	ErrInvalidBoxLength       = errors.New("invalid box length")
	ErrUnexpectedEOF          = errors.New("unexpected end of file")
	ErrMissingRequiredBox     = errors.New("missing required box")
	ErrInvalidBoxType         = errors.New("invalid box type")
	ErrRecursionDepthExceeded = errors.New("box recursion depth exceeded")
	ErrBoxCountExceeded       = errors.New("maximum box count exceeded")
	ErrInvalidImageHeader     = errors.New("invalid image header")
	ErrInvalidColourSpec      = errors.New("invalid colour specification")
	ErrNoCodestream           = errors.New("no codestream found")
)

Errors

View Source 
var J2KSignature = []byte{0xFF, 0x4F, 0xFF, 0x51}

J2KSignature contains the J2K codestream signature (SOC marker)

View Source 
var JP2Signature = []byte{
	0x00, 0x00, 0x00, 0x0C,
	0x6A, 0x50, 0x20, 0x20,
	0x0D, 0x0A, 0x87, 0x0A,
}

JP2Signature contains the JP2 signature bytes

Functions

This section is empty.

Types

type Box 

type Box struct {
	Type     uint32 // 4-byte box type
	Length   uint64 // Box length (including header)
	Offset   int64  // Offset in file
	Data     []byte // Box content (excluding header)
	Children []*Box // Child boxes for superboxes
}

Box represents a JP2 box structure

func (*Box) TypeString 

func (b *Box) TypeString() string

TypeString returns the box type as a 4-character string

type ColourSpec 

type ColourSpec struct {
	Method     uint8  // Specification method (1=enumerated, 2=ICC profile)
	Precedence uint8  // Precedence
	Approx     uint8  // Colourspace approximation
	EnumCS     uint32 // Enumerated colourspace (if method=1)
	ICCProfile []byte // ICC profile data (if method=2)
}

ColourSpec contains colour specification box data

type FileType 

type FileType struct {
	Brand         uint32   // Brand identifier
	MinorVersion  uint32   // Minor version
	Compatibility []uint32 // Compatibility list
}

FileType contains file type box data

type ImageHeader 

type ImageHeader struct {
	Height          uint32 // Image height
	Width           uint32 // Image width
	NumComponents   uint16 // Number of components
	BitsPerComp     uint8  // Bits per component (7-bit value)
	CompressionType uint8  // Compression type (7 = wavelet)
	UnknownColour   uint8  // Unknown colourspace flag
	IntellProp      uint8  // Intellectual property flag
}

ImageHeader contains JP2 image header box data

type JP2File 

type JP2File struct {
	Signature  *Box       // Signature box
	FileType   *FileType  // File type box
	Header     *JP2Header // JP2 header
	Codestream []byte     // Raw codestream data
	Boxes      []*Box     // All top-level boxes
	IsRawJ2K   bool       // True if raw J2K without JP2 wrapper
}

JP2File represents a parsed JP2 file

type JP2Header 

type JP2Header struct {
	ImageHeader *ImageHeader // Image header (ihdr)
	ColourSpec  *ColourSpec  // Colour specification (colr)
	Palette     *Box         // Palette box (pclr) - optional
	CompMap     *Box         // Component mapping (cmap) - optional
	ChanDef     *Box         // Channel definition (cdef) - optional
	Resolution  *Box         // Resolution (res ) - optional
	BPC         *Box         // Bits per component (bpcc) - optional
}

JP2Header contains the parsed JP2 header superbox content

type Parser 

type Parser struct {
	// contains filtered or unexported fields
}

Parser handles JP2/J2K file parsing

func NewParser 

func NewParser() *Parser

NewParser creates a new JP2/J2K parser

func (*Parser) IsJP2 

func (p *Parser) IsJP2(data []byte) bool

IsJP2 checks if data starts with JP2 signature

func (*Parser) IsRawJ2K 

func (p *Parser) IsRawJ2K(data []byte) bool

IsRawJ2K checks if data starts with J2K codestream (SOC marker)

func (*Parser) Parse 

func (p *Parser) Parse(r io.Reader) (*JP2File, error)

Parse parses a JP2 or raw J2K file

func (*Parser) ParseBox 

func (p *Parser) ParseBox(r io.ReadSeeker, offset int64, _ int) (*Box, error)

ParseBox parses a single box from the reader

func (*Parser) ParseColourSpec 

func (p *Parser) ParseColourSpec(box *Box) (*ColourSpec, error)

ParseColourSpec parses a colour specification box (colr)

func (*Parser) ParseFileType 

func (p *Parser) ParseFileType(box *Box) (*FileType, error)

ParseFileType parses a file type box (ftyp)

func (*Parser) ParseImageHeader 

func (p *Parser) ParseImageHeader(box *Box) (*ImageHeader, error)

ParseImageHeader parses an image header box (ihdr)

func (*Parser) ParseJP2Header 

func (p *Parser) ParseJP2Header(box *Box) (*JP2Header, error)

ParseJP2Header parses a JP2 header superbox

func (*Parser) ParseSuperboxChildren 

func (p *Parser) ParseSuperboxChildren(box *Box, depth int) error

ParseSuperboxChildren parses child boxes within a superbox

func (*Parser) Reset 

func (p *Parser) Reset()

Reset resets the parser state for reuse

func (*Parser) ValidateSignature 

func (p *Parser) ValidateSignature(data []byte) error

ValidateSignature validates the JP2 12-byte signature

Source Files

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