cogger

type Config ¶ added in v0.1.0

type Config struct {
	//Encoding selects big or little endian tiff encoding. Default: little
	Encoding binary.ByteOrder

	//BigTIFF forces bigtiff creation. Default: false, i.e. only if needed
	BigTIFF bool

	// PlanarInterleaving for separate-plane files.
	// Default: nil resulting in {{0,1,...n}} i.e. interleaved planes
	PlanarInterleaving PlanarInterleaving

	//WithGDALGhostArea inserts gdal specific read optimizations
	WithGDALGhostArea bool
}

func DefaultConfig() Config

func (cfg Config) Rewrite(out io.Writer, readers ...tiff.ReadAtReadSeeker) error

func (cfg Config) RewriteIFDHeader(ifd *IFD, out io.Writer) error

func (cfg Config) RewriteIFDTree(ifd *IFD, out io.Writer) error

func (cfg Config) RewriteIFDTreeSplitted(ifd *IFD, headerOut, tileDataOut io.Writer) error

func (cfg Config) RewriteSplitted(headerOut, dataOut io.Writer, readers ...tiff.ReadAtReadSeeker) error

type Dag ¶ added in v0.1.0

type Dag [][]Node

A DAG can be used further optimize parrallel strip computing, by explicitely referencing which parent strips are needed to be used to downsample the given strip of an overview. For advanced usage; it is simpler to process all images of a pyramid level in parallel before moving down to the next level

type ErrInvalidOption ¶ added in v0.1.0

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

func (err ErrInvalidOption) Error() string

type IFD ¶

type IFD struct {
	//Any field added here should also be accounted for in computeStructure and writeIFD
	SubfileType               uint32   `tiff:"field,tag=254"`
	ImageWidth                uint64   `tiff:"field,tag=256"`
	ImageHeight               uint64   `tiff:"field,tag=257"`
	BitsPerSample             []uint16 `tiff:"field,tag=258"`
	Compression               uint16   `tiff:"field,tag=259"`
	PhotometricInterpretation uint16   `tiff:"field,tag=262"`
	DocumentName              string   `tiff:"field,tag=269"`
	SamplesPerPixel           uint16   `tiff:"field,tag=277"`
	PlanarConfiguration       uint16   `tiff:"field,tag=284"`
	Software                  string   `tiff:"field,tag=305"`
	DateTime                  string   `tiff:"field,tag=306"`
	Predictor                 uint16   `tiff:"field,tag=317"`
	Colormap                  []uint16 `tiff:"field,tag=320"`
	TileWidth                 uint16   `tiff:"field,tag=322"`
	TileHeight                uint16   `tiff:"field,tag=323"`
	TileOffsets               []uint64 `tiff:"field,tag=324"`
	TileByteCounts            []uint64 `tiff:"field,tag=325"`
	ExtraSamples              []uint16 `tiff:"field,tag=338"`
	SampleFormat              []uint16 `tiff:"field,tag=339"`
	JPEGTables                []byte   `tiff:"field,tag=347"`

	Copyright              string    `tiff:"field,tag=33432"`
	ModelPixelScaleTag     []float64 `tiff:"field,tag=33550"`
	ModelTiePointTag       []float64 `tiff:"field,tag=33922"`
	ModelTransformationTag []float64 `tiff:"field,tag=34264"`
	GeoKeyDirectoryTag     []uint16  `tiff:"field,tag=34735"`
	GeoDoubleParamsTag     []float64 `tiff:"field,tag=34736"`
	GeoAsciiParamsTag      string    `tiff:"field,tag=34737"`
	GDALMetaData           string    `tiff:"field,tag=42112"`
	NoData                 string    `tiff:"field,tag=42113"`
	LERCParams             []uint32  `tiff:"field,tag=50674"`
	RPCs                   []float64 `tiff:"field,tag=50844"`
	LoadTile               func(idx int, data []byte) error
	// contains filtered or unexported fields
}

func (ifd *IFD) AddMask(msk *IFD) error

func (ifd *IFD) AddOverview(ovr *IFD) error

func (ifd *IFD) NPlanes() int

func (ifd *IFD) NTilesX() int

func (ifd *IFD) NTilesY() int

func (ifd *IFD) SetPlanarInterleaving(pi PlanarInterleaving) error

func (ifd *IFD) TileFromIdx(idx int) (x, y, plane int)

func (ifd *IFD) TileIdx(x, y, plane int) int

type Image ¶ added in v0.1.0

type Image struct {
	Width, Height int
	Strips        []Strip
	// contains filtered or unexported fields
}

An Image is a Width*Height rectangle of pixels (i.e. there are no overviews at this level) and its decompostion into Strips that can be processed concurrently

type Node ¶ added in v0.1.0

type Node struct {
	// Parents are the indexes of the parent strips that will be used to compose the current strip
	Parents []int
	//ParentOffset is the Y position in the parent image of the top-most parent strip
	ParentOffset int
}

A Node represents a single Strip in the Dag

type PlanarInterleaving ¶ added in v0.1.0

type PlanarInterleaving [][]int

PlanarInterleaving describes how the band data should be interleaved for tiffs with more than 1 plane and with PlanarConfiguration=2

This is an advanced usage option that does not modify the actual image data but tweaks the order in which each plane's (i.e. band's) tile is written in the resulting file.

Examples for a 3-band rgb image:

• [[0,1,2]] will result in tiles written in the order r1,g1,b1,r2,g2,b2...rn,gn,bn. This is the default.
• [0],[1],[2]] => r1,r2...rn,g1,g2....gn,b1,b2...bn
• [0],[2],[1]] => r1,r2...rn,b1,b2....bn,g1,g2...gn
• [0,1],[2]] => r1,g1,r2,g2...rn,gn,b1,b2....bn

Examples for a 3-band rgb image with mask:

• [[0,1,2,3]] will result in tiles written in the order r1,g1,b1,m1,r2,g2,b2,m2...rn,gn,bn,mn. This is the default.
• [0],[1],[2],[3]] => r1,r2...rn,g1,g2...gn,b1,b2...bn,m1,m2...mn
• [0],[3],[2],[1]] => r1,r2...rn,m1,m2...m3,b1,b2...bn,g1,g2...gn
• [0,1],[2],[3]] => r1,g1,r2,g2...rn,gn,b1,b2....bn,m1m2...mn

For a n-band image, each band index from 0 to n-1 must appear exactly once in the array. If the image also has a mask, the index n must also appear exactly once and represents the mask position.

type Pyramid ¶ added in v0.1.0

type Pyramid []Image

The Image at index 0 is the full resolution image, and Pyramid[0]'s Strip's Source properties reference the pixel frame of the input image.

The Images at index >0 are the overviews, who's Strip's sources reference the image at the previous index

func (pyr Pyramid) DAG() Dag

type Strip ¶ added in v0.1.0

type Strip struct {
	Width, Height            int
	TopLeftX, TopLeftY       int
	SrcTopLeftX, SrcTopLeftY float64
	SrcWidth, SrcHeight      float64
}

A Strip is the basic building block of an Image, and corresponds to a rectangle of Width*Height pixels who's upper left corner is TopLeftX,TopLeftY. The TopLeftX and TopLeftY properties are informative only and are not needed in order to process an image with this API.

In order to populate the pixels of a given strip, data must be copied or downsampled from a window of a source Image. Depending on the context, the source can either be the original image when creating the full-resolution IFD, or the full-resolution IFD when creating the first overview, or the previous overview when creating another overview. The source window is defined by it's upper left corner (SrcTopLeftX and SrcTopLeftY) and size (SrcWidth and SrcHeight)

In gdal lingo, this strip can be calculated by running

gdal_translate source_dataset.tif strip.tif -srcwin <SrcTopLeftX> <SrcTopLeftY> <SrcWidth> <SrcHeight> -outsize <Width> <Height> -r average

type Stripper ¶ added in v0.1.0

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

A Stripper holds the information to inform how to split an image and its overviews into strips of roughly similar sizes, allowing these strips to be produced outside of the cogger library itself, and ensuring that the internal tiling of these individaul strips will be compatible with a cog reconstruction.

The usual workflow is to create a Stripper matching the input image's dimensions, rough size of each strip to be processed, and output cog parameters (namely internal tiling size)

For a full example, see the cmd/pcogger utility

// let's imagine we have an input.jp2 file of size 12345x23456 pixels, that we want to convert to a cog
//
// we will do this in parallel using gdal and cogger, using the stripper class to subdivide the task

inputFile := os.Getenv("STRIPPER_INPUT")
if inputFile == "" {
	inputFile = "input.jp2"
}
width, _ := strconv.Atoi(os.Getenv("STRIPPER_WIDTH"))
if width == 0 {
	width = 12345
}
height, _ := strconv.Atoi(os.Getenv("STRIPPER_HEIGHT"))
if height == 0 {
	height = 23456
}

stripper, _ := NewStripper(width, height)

pyr := stripper.Pyramid()

tx, ty := stripper.InternalTileSize()
copts := fmt.Sprintf("-co TILED=YES -co COMPRESS=LZW -co BLOCKXSIZE=%d -co BLOCKYSIZE=%d", tx, ty)

srcStrips := [][]tiff.ReadAtReadSeeker{} //used to accumulate the readers of intermediate strips. the ordering must be identical to Pyramid/Pyramid.Strips

vrt_accum := []string{}
for l := range pyr {
	fmt.Printf("\nbatch %d\n\n", l+1)
	infile := inputFile
	if l > 0 {
		// if we are in an overview level, optionally build a vrt file making a single gdal image from the all the strips created at the previous level
		if len(vrt_accum) > 1 {
			infile = fmt.Sprintf("l_%d.vrt", l-1)
			fmt.Printf("gdalbuildvrt %s %s\n", infile, strings.Join(vrt_accum, " "))
		} else {
			infile = vrt_accum[0]
		}
		vrt_accum = []string{}
	}

	lStrips := []tiff.ReadAtReadSeeker{}
	for s, strip := range pyr[l].Strips {
		stripname := fmt.Sprintf("tmp_%d_%d.tif", l, s)
		vrt_accum = append(vrt_accum, stripname)
		resizeOpts := ""
		if l > 0 {
			resizeOpts = fmt.Sprintf("-outsize %d %d -r average", strip.Width, strip.Height)
		}
		fmt.Printf("gdal_translate %s %s %s %s -srcwin 0 %g %g %g\n", infile, stripname, copts, resizeOpts,
			strip.SrcTopLeftY, strip.SrcWidth, strip.SrcHeight)
		rs, _ := os.Open(stripname)
		lStrips = append(lStrips, rs)
	}
	srcStrips = append(srcStrips, lStrips)
}

outcog, _ := os.Create("stripper-example-output.tif")
//defer os.Remove(outcog.Name())

ifdtree, _ := stripper.AssembleStrips(srcStrips)
_ = ifdtree

DefaultConfig().RewriteIFDTree(ifdtree, outcog)
outcog.Close()

////output: foo

func NewStripper(width, height int, options ...StripperOption) (Stripper, error)

func (t Stripper) AssembleStrips(srcStrips [][]tiff.ReadAtReadSeeker) (*IFD, error)

func (s Stripper) FullresStripHeightMultiple() int

func (s Stripper) InternalTileSize() (int, int)

func (s Stripper) MinOverviewSize() int

func (s Stripper) OverviewCount() int

func (t Stripper) Pyramid() Pyramid

func (s Stripper) Size() (int, int)

func (s Stripper) TargetPixelCount() int

type StripperOption ¶ added in v0.1.0

type StripperOption func(t *Stripper) error

func FullresStripHeightMultiple(heightBase int) StripperOption

func InternalTileSize(width, height int) StripperOption

func MinOverviewSize(size int) StripperOption

func OverviewCount(count int) StripperOption

func TargetPixelCount(count int) StripperOption