jp2info

Documentation

Index

• Variables
• type ColorMethod
• type ColorSpace
  • func (cs ColorSpace) String() string
• type Info
  • func (i *Info) TileHeight() uint32
  • func (i *Info) TileWidth() uint32
• type Scanner
  • func (s *Scanner) Scan(filename string) (*Info, error)

Variables

var (
	IHDR   = []byte{0x69, 0x68, 0x64, 0x72} // "ihdr"
	COLR   = []byte{0x63, 0x6f, 0x6c, 0x72} // "colr"
	SOCSIZ = []byte{0xFF, 0x4F, 0xFF, 0x51}
	COD    = []byte{0xFF, 0x52}
)

Various hard-coded byte values for finding JP2 boxes

var JP2HEADER = []byte{
	0x00, 0x00, 0x00, 0x0c,
	0x6a, 0x50, 0x20, 0x20,
	0x0d, 0x0a, 0x87, 0x0a,
}

JP2HEADER contains the raw bytes for the only JP2 header we currently respect

Types

type ColorMethod

type ColorMethod uint8

ColorMethod tells us how to determine the colorspace

const (
	CMEnumerated    ColorMethod = 1
	CMRestrictedICC             = 2
)

Known color methods

type ColorSpace

type ColorSpace uint8

ColorSpace tells us how to parse color data coming from openjpeg

const (
	CSUnknown ColorSpace = iota
	CSRGB
	CSGrayScale
	CSYCC
)

Known color spaces

func (ColorSpace) String

func (cs ColorSpace) String() string

String reports the ColorSpace in a human-readable way

type Info

type Info struct {
	// Main header info
	Width, Height uint32
	Comps         uint16
	BPC           uint8

	// Color data
	ColorMethod  ColorMethod
	ColorSpace   ColorSpace
	Prec, Approx uint8

	// From SIZ box - this data can replace the main header data and
	// some of the colorspace data if necessary
	LSiz, RSiz     uint16
	XSiz, YSiz     uint32
	XOSiz, YOSiz   uint32
	XTSiz, YTSiz   uint32
	XTOSiz, YTOSiz uint32
	CSiz           uint16

	// From COD box
	LCod   uint16
	SCod   uint8
	SGCod  uint32
	Levels uint8
}

Info stores a variety of data we can easily scan from a jpeg2000 header

func (*Info) TileHeight

func (i *Info) TileHeight() uint32

TileHeight computes height of tiles

func (*Info) TileWidth

func (i *Info) TileWidth() uint32

TileWidth computes width of tiles

type Scanner

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

Scanner reads a Jpeg2000 header and parsing its data into an Info structure

func (*Scanner) Scan

func (s *Scanner) Scan(filename string) (*Info, error)

Scan reads the file and populates an Info pointer