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Package image

Overview

Package image implements a basic 2-D image library.

The fundamental interface is called Image. An Image contains colors, which are described in the image/color package.

Values of the Image interface are created either by calling functions such as NewRGBA and NewPaletted, or by calling Decode on an io.Reader containing image data in a format such as GIF, JPEG or PNG. Decoding any particular image format requires the prior registration of a decoder function. Registration is typically automatic as a side effect of initializing that format's package so that, to decode a PNG image, it suffices to have

import _ "image/png"

in a program's main package. The _ means to import a package purely for its initialization side effects.

See "The Go image package" for more details: https://golang.org/doc/articles/image_package.html

Example

// This example demonstrates decoding a JPEG image and examining its pixels.
package main

import (
	"encoding/base64"
	"fmt"
	"image"
	"log"
	"strings"

	// Package image/jpeg is not used explicitly in the code below,
	// but is imported for its initialization side-effect, which allows
	// image.Decode to understand JPEG formatted images. Uncomment these
	// two lines to also understand GIF and PNG images:
	// _ "image/gif"
	// _ "image/png"
	_ "image/jpeg"
)

func main() {
	// Decode the JPEG data. If reading from file, create a reader with
	//
	// reader, err := os.Open("testdata/video-001.q50.420.jpeg")
	// if err != nil {
	//     log.Fatal(err)
	// }
	// defer reader.Close()
	reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
	m, _, err := image.Decode(reader)
	if err != nil {
		log.Fatal(err)
	}
	bounds := m.Bounds()

	// Calculate a 16-bin histogram for m's red, green, blue and alpha components.
	//
	// An image's bounds do not necessarily start at (0, 0), so the two loops start
	// at bounds.Min.Y and bounds.Min.X. Looping over Y first and X second is more
	// likely to result in better memory access patterns than X first and Y second.
	var histogram [16][4]int
	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
		for x := bounds.Min.X; x < bounds.Max.X; x++ {
			r, g, b, a := m.At(x, y).RGBA()
			// A color's RGBA method returns values in the range [0, 65535].
			// Shifting by 12 reduces this to the range [0, 15].
			histogram[r>>12][0]++
			histogram[g>>12][1]++
			histogram[b>>12][2]++
			histogram[a>>12][3]++
		}
	}

	// Print the results.
	fmt.Printf("%-14s %6s %6s %6s %6s\n", "bin", "red", "green", "blue", "alpha")
	for i, x := range histogram {
		fmt.Printf("0x%04x-0x%04x: %6d %6d %6d %6d\n", i<<12, (i+1)<<12-1, x[0], x[1], x[2], x[3])
	}
}

const data = `
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`

Index

Examples

Package

Package files

format.go geom.go image.go names.go ycbcr.go

Variables

var (
        // Black is an opaque black uniform image.
        Black = NewUniform(color.Black)
        // White is an opaque white uniform image.
        White = NewUniform(color.White)
        // Transparent is a fully transparent uniform image.
        Transparent = NewUniform(color.Transparent)
        // Opaque is a fully opaque uniform image.
        Opaque = NewUniform(color.Opaque)
)

ErrFormat indicates that decoding encountered an unknown format.

var ErrFormat = errors.New("image: unknown format")

func RegisterFormatSource

func RegisterFormat(name, magic string, decode func(io.Reader) (Image, error), decodeConfig func(io.Reader) (Config, error))

RegisterFormat registers an image format for use by Decode. Name is the name of the format, like "jpeg" or "png". Magic is the magic prefix that identifies the format's encoding. The magic string can contain "?" wildcards that each match any one byte. Decode is the function that decodes the encoded image. DecodeConfig is the function that decodes just its configuration.

type AlphaSource

Alpha is an in-memory image whose At method returns color.Alpha values.

type Alpha struct {
        // Pix holds the image's pixels, as alpha values. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewAlphaSource

func NewAlpha(r Rectangle) *Alpha

NewAlpha returns a new Alpha image with the given bounds.

func (*Alpha) AlphaAtSource

func (p *Alpha) AlphaAt(x, y int) color.Alpha

func (*Alpha) AtSource

func (p *Alpha) At(x, y int) color.Color

func (*Alpha) BoundsSource

func (p *Alpha) Bounds() Rectangle

func (*Alpha) ColorModelSource

func (p *Alpha) ColorModel() color.Model

func (*Alpha) OpaqueSource

func (p *Alpha) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Alpha) PixOffsetSource

func (p *Alpha) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*Alpha) SetSource

func (p *Alpha) Set(x, y int, c color.Color)

func (*Alpha) SetAlphaSource

func (p *Alpha) SetAlpha(x, y int, c color.Alpha)

func (*Alpha) SubImageSource

func (p *Alpha) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type Alpha16Source

Alpha16 is an in-memory image whose At method returns color.Alpha16 values.

type Alpha16 struct {
        // Pix holds the image's pixels, as alpha values in big-endian format. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewAlpha16Source

func NewAlpha16(r Rectangle) *Alpha16

NewAlpha16 returns a new Alpha16 image with the given bounds.

func (*Alpha16) Alpha16AtSource

func (p *Alpha16) Alpha16At(x, y int) color.Alpha16

func (*Alpha16) AtSource

func (p *Alpha16) At(x, y int) color.Color

func (*Alpha16) BoundsSource

func (p *Alpha16) Bounds() Rectangle

func (*Alpha16) ColorModelSource

func (p *Alpha16) ColorModel() color.Model

func (*Alpha16) OpaqueSource

func (p *Alpha16) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Alpha16) PixOffsetSource

func (p *Alpha16) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*Alpha16) SetSource

func (p *Alpha16) Set(x, y int, c color.Color)

func (*Alpha16) SetAlpha16Source

func (p *Alpha16) SetAlpha16(x, y int, c color.Alpha16)

func (*Alpha16) SubImageSource

func (p *Alpha16) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type CMYKSource

CMYK is an in-memory image whose At method returns color.CMYK values.

type CMYK struct {
        // Pix holds the image's pixels, in C, M, Y, K order. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewCMYKSource

func NewCMYK(r Rectangle) *CMYK

NewCMYK returns a new CMYK image with the given bounds.

func (*CMYK) AtSource

func (p *CMYK) At(x, y int) color.Color

func (*CMYK) BoundsSource

func (p *CMYK) Bounds() Rectangle

func (*CMYK) CMYKAtSource

func (p *CMYK) CMYKAt(x, y int) color.CMYK

func (*CMYK) ColorModelSource

func (p *CMYK) ColorModel() color.Model

func (*CMYK) OpaqueSource

func (p *CMYK) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*CMYK) PixOffsetSource

func (p *CMYK) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*CMYK) SetSource

func (p *CMYK) Set(x, y int, c color.Color)

func (*CMYK) SetCMYKSource

func (p *CMYK) SetCMYK(x, y int, c color.CMYK)

func (*CMYK) SubImageSource

func (p *CMYK) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type ConfigSource

Config holds an image's color model and dimensions.

type Config struct {
        ColorModel    color.Model
        Width, Height int
}

func DecodeConfigSource

func DecodeConfig(r io.Reader) (Config, string, error)

DecodeConfig decodes the color model and dimensions of an image that has been encoded in a registered format. The string returned is the format name used during format registration. Format registration is typically done by an init function in the codec-specific package.

type GraySource

Gray is an in-memory image whose At method returns color.Gray values.

type Gray struct {
        // Pix holds the image's pixels, as gray values. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewGraySource

func NewGray(r Rectangle) *Gray

NewGray returns a new Gray image with the given bounds.

func (*Gray) AtSource

func (p *Gray) At(x, y int) color.Color

func (*Gray) BoundsSource

func (p *Gray) Bounds() Rectangle

func (*Gray) ColorModelSource

func (p *Gray) ColorModel() color.Model

func (*Gray) GrayAtSource

func (p *Gray) GrayAt(x, y int) color.Gray

func (*Gray) OpaqueSource

func (p *Gray) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Gray) PixOffsetSource

func (p *Gray) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*Gray) SetSource

func (p *Gray) Set(x, y int, c color.Color)

func (*Gray) SetGraySource

func (p *Gray) SetGray(x, y int, c color.Gray)

func (*Gray) SubImageSource

func (p *Gray) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type Gray16Source

Gray16 is an in-memory image whose At method returns color.Gray16 values.

type Gray16 struct {
        // Pix holds the image's pixels, as gray values in big-endian format. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewGray16Source

func NewGray16(r Rectangle) *Gray16

NewGray16 returns a new Gray16 image with the given bounds.

func (*Gray16) AtSource

func (p *Gray16) At(x, y int) color.Color

func (*Gray16) BoundsSource

func (p *Gray16) Bounds() Rectangle

func (*Gray16) ColorModelSource

func (p *Gray16) ColorModel() color.Model

func (*Gray16) Gray16AtSource

func (p *Gray16) Gray16At(x, y int) color.Gray16

func (*Gray16) OpaqueSource

func (p *Gray16) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Gray16) PixOffsetSource

func (p *Gray16) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*Gray16) SetSource

func (p *Gray16) Set(x, y int, c color.Color)

func (*Gray16) SetGray16Source

func (p *Gray16) SetGray16(x, y int, c color.Gray16)

func (*Gray16) SubImageSource

func (p *Gray16) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type ImageSource

Image is a finite rectangular grid of color.Color values taken from a color model.

type Image interface {
        // ColorModel returns the Image's color model.
        ColorModel() color.Model
        // Bounds returns the domain for which At can return non-zero color.
        // The bounds do not necessarily contain the point (0, 0).
        Bounds() Rectangle
        // At returns the color of the pixel at (x, y).
        // At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
        // At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.
        At(x, y int) color.Color
}

func DecodeSource

func Decode(r io.Reader) (Image, string, error)

Decode decodes an image that has been encoded in a registered format. The string returned is the format name used during format registration. Format registration is typically done by an init function in the codec- specific package.

type NRGBASource

NRGBA is an in-memory image whose At method returns color.NRGBA values.

type NRGBA struct {
        // Pix holds the image's pixels, in R, G, B, A order. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewNRGBASource

func NewNRGBA(r Rectangle) *NRGBA

NewNRGBA returns a new NRGBA image with the given bounds.

func (*NRGBA) AtSource

func (p *NRGBA) At(x, y int) color.Color

func (*NRGBA) BoundsSource

func (p *NRGBA) Bounds() Rectangle

func (*NRGBA) ColorModelSource

func (p *NRGBA) ColorModel() color.Model

func (*NRGBA) NRGBAAtSource

func (p *NRGBA) NRGBAAt(x, y int) color.NRGBA

func (*NRGBA) OpaqueSource

func (p *NRGBA) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*NRGBA) PixOffsetSource

func (p *NRGBA) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*NRGBA) SetSource

func (p *NRGBA) Set(x, y int, c color.Color)

func (*NRGBA) SetNRGBASource

func (p *NRGBA) SetNRGBA(x, y int, c color.NRGBA)

func (*NRGBA) SubImageSource

func (p *NRGBA) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type NRGBA64Source

NRGBA64 is an in-memory image whose At method returns color.NRGBA64 values.

type NRGBA64 struct {
        // Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewNRGBA64Source

func NewNRGBA64(r Rectangle) *NRGBA64

NewNRGBA64 returns a new NRGBA64 image with the given bounds.

func (*NRGBA64) AtSource

func (p *NRGBA64) At(x, y int) color.Color

func (*NRGBA64) BoundsSource

func (p *NRGBA64) Bounds() Rectangle

func (*NRGBA64) ColorModelSource

func (p *NRGBA64) ColorModel() color.Model

func (*NRGBA64) NRGBA64AtSource

func (p *NRGBA64) NRGBA64At(x, y int) color.NRGBA64

func (*NRGBA64) OpaqueSource

func (p *NRGBA64) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*NRGBA64) PixOffsetSource

func (p *NRGBA64) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*NRGBA64) SetSource

func (p *NRGBA64) Set(x, y int, c color.Color)

func (*NRGBA64) SetNRGBA64Source

func (p *NRGBA64) SetNRGBA64(x, y int, c color.NRGBA64)

func (*NRGBA64) SubImageSource

func (p *NRGBA64) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type NYCbCrASource

NYCbCrA is an in-memory image of non-alpha-premultiplied Y'CbCr-with-alpha colors. A and AStride are analogous to the Y and YStride fields of the embedded YCbCr.

type NYCbCrA struct {
        YCbCr
        A       []uint8
        AStride int
}

func NewNYCbCrASource

func NewNYCbCrA(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *NYCbCrA

NewNYCbCrA returns a new NYCbCrA image with the given bounds and subsample ratio.

func (*NYCbCrA) AOffsetSource

func (p *NYCbCrA) AOffset(x, y int) int

AOffset returns the index of the first element of A that corresponds to the pixel at (x, y).

func (*NYCbCrA) AtSource

func (p *NYCbCrA) At(x, y int) color.Color

func (*NYCbCrA) ColorModelSource

func (p *NYCbCrA) ColorModel() color.Model

func (*NYCbCrA) NYCbCrAAtSource

func (p *NYCbCrA) NYCbCrAAt(x, y int) color.NYCbCrA

func (*NYCbCrA) OpaqueSource

func (p *NYCbCrA) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*NYCbCrA) SubImageSource

func (p *NYCbCrA) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type PalettedSource

Paletted is an in-memory image of uint8 indices into a given palette.

type Paletted struct {
        // Pix holds the image's pixels, as palette indices. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
        // Palette is the image's palette.
        Palette color.Palette
}

func NewPalettedSource

func NewPaletted(r Rectangle, p color.Palette) *Paletted

NewPaletted returns a new Paletted image with the given width, height and palette.

func (*Paletted) AtSource

func (p *Paletted) At(x, y int) color.Color

func (*Paletted) BoundsSource

func (p *Paletted) Bounds() Rectangle

func (*Paletted) ColorIndexAtSource

func (p *Paletted) ColorIndexAt(x, y int) uint8

func (*Paletted) ColorModelSource

func (p *Paletted) ColorModel() color.Model

func (*Paletted) OpaqueSource

func (p *Paletted) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Paletted) PixOffsetSource

func (p *Paletted) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*Paletted) SetSource

func (p *Paletted) Set(x, y int, c color.Color)

func (*Paletted) SetColorIndexSource

func (p *Paletted) SetColorIndex(x, y int, index uint8)

func (*Paletted) SubImageSource

func (p *Paletted) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type PalettedImageSource

PalettedImage is an image whose colors may come from a limited palette. If m is a PalettedImage and m.ColorModel() returns a color.Palette p, then m.At(x, y) should be equivalent to p[m.ColorIndexAt(x, y)]. If m's color model is not a color.Palette, then ColorIndexAt's behavior is undefined.

type PalettedImage interface {
        // ColorIndexAt returns the palette index of the pixel at (x, y).
        ColorIndexAt(x, y int) uint8
        Image
}

type PointSource

A Point is an X, Y coordinate pair. The axes increase right and down.

type Point struct {
        X, Y int
}

ZP is the zero Point.

var ZP Point

func PtSource

func Pt(X, Y int) Point

Pt is shorthand for Point{X, Y}.

func (Point) AddSource

func (p Point) Add(q Point) Point

Add returns the vector p+q.

func (Point) DivSource

func (p Point) Div(k int) Point

Div returns the vector p/k.

func (Point) EqSource

func (p Point) Eq(q Point) bool

Eq reports whether p and q are equal.

func (Point) InSource

func (p Point) In(r Rectangle) bool

In reports whether p is in r.

func (Point) ModSource

func (p Point) Mod(r Rectangle) Point

Mod returns the point q in r such that p.X-q.X is a multiple of r's width and p.Y-q.Y is a multiple of r's height.

func (Point) MulSource

func (p Point) Mul(k int) Point

Mul returns the vector p*k.

func (Point) StringSource

func (p Point) String() string

String returns a string representation of p like "(3,4)".

func (Point) SubSource

func (p Point) Sub(q Point) Point

Sub returns the vector p-q.

type RGBASource

RGBA is an in-memory image whose At method returns color.RGBA values.

type RGBA struct {
        // Pix holds the image's pixels, in R, G, B, A order. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewRGBASource

func NewRGBA(r Rectangle) *RGBA

NewRGBA returns a new RGBA image with the given bounds.

func (*RGBA) AtSource

func (p *RGBA) At(x, y int) color.Color

func (*RGBA) BoundsSource

func (p *RGBA) Bounds() Rectangle

func (*RGBA) ColorModelSource

func (p *RGBA) ColorModel() color.Model

func (*RGBA) OpaqueSource

func (p *RGBA) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*RGBA) PixOffsetSource

func (p *RGBA) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*RGBA) RGBAAtSource

func (p *RGBA) RGBAAt(x, y int) color.RGBA

func (*RGBA) SetSource

func (p *RGBA) Set(x, y int, c color.Color)

func (*RGBA) SetRGBASource

func (p *RGBA) SetRGBA(x, y int, c color.RGBA)

func (*RGBA) SubImageSource

func (p *RGBA) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type RGBA64Source

RGBA64 is an in-memory image whose At method returns color.RGBA64 values.

type RGBA64 struct {
        // Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at
        // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8].
        Pix []uint8
        // Stride is the Pix stride (in bytes) between vertically adjacent pixels.
        Stride int
        // Rect is the image's bounds.
        Rect Rectangle
}

func NewRGBA64Source

func NewRGBA64(r Rectangle) *RGBA64

NewRGBA64 returns a new RGBA64 image with the given bounds.

func (*RGBA64) AtSource

func (p *RGBA64) At(x, y int) color.Color

func (*RGBA64) BoundsSource

func (p *RGBA64) Bounds() Rectangle

func (*RGBA64) ColorModelSource

func (p *RGBA64) ColorModel() color.Model

func (*RGBA64) OpaqueSource

func (p *RGBA64) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*RGBA64) PixOffsetSource

func (p *RGBA64) PixOffset(x, y int) int

PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).

func (*RGBA64) RGBA64AtSource

func (p *RGBA64) RGBA64At(x, y int) color.RGBA64

func (*RGBA64) SetSource

func (p *RGBA64) Set(x, y int, c color.Color)

func (*RGBA64) SetRGBA64Source

func (p *RGBA64) SetRGBA64(x, y int, c color.RGBA64)

func (*RGBA64) SubImageSource

func (p *RGBA64) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

type RectangleSource

A Rectangle contains the points with Min.X <= X < Max.X, Min.Y <= Y < Max.Y. It is well-formed if Min.X <= Max.X and likewise for Y. Points are always well-formed. A rectangle's methods always return well-formed outputs for well-formed inputs.

A Rectangle is also an Image whose bounds are the rectangle itself. At returns color.Opaque for points in the rectangle and color.Transparent otherwise.

type Rectangle struct {
        Min, Max Point
}

ZR is the zero Rectangle.

var ZR Rectangle

func RectSource

func Rect(x0, y0, x1, y1 int) Rectangle

Rect is shorthand for Rectangle{Pt(x0, y0), Pt(x1, y1)}. The returned rectangle has minimum and maximum coordinates swapped if necessary so that it is well-formed.

func (Rectangle) AddSource

func (r Rectangle) Add(p Point) Rectangle

Add returns the rectangle r translated by p.

func (Rectangle) AtSource

func (r Rectangle) At(x, y int) color.Color

At implements the Image interface.

func (Rectangle) BoundsSource

func (r Rectangle) Bounds() Rectangle

Bounds implements the Image interface.

func (Rectangle) CanonSource

func (r Rectangle) Canon() Rectangle

Canon returns the canonical version of r. The returned rectangle has minimum and maximum coordinates swapped if necessary so that it is well-formed.

func (Rectangle) ColorModelSource

func (r Rectangle) ColorModel() color.Model

ColorModel implements the Image interface.

func (Rectangle) DxSource

func (r Rectangle) Dx() int

Dx returns r's width.

func (Rectangle) DySource

func (r Rectangle) Dy() int

Dy returns r's height.

func (Rectangle) EmptySource

func (r Rectangle) Empty() bool

Empty reports whether the rectangle contains no points.

func (Rectangle) EqSource

func (r Rectangle) Eq(s Rectangle) bool

Eq reports whether r and s contain the same set of points. All empty rectangles are considered equal.

func (Rectangle) InSource

func (r Rectangle) In(s Rectangle) bool

In reports whether every point in r is in s.

func (Rectangle) InsetSource

func (r Rectangle) Inset(n int) Rectangle

Inset returns the rectangle r inset by n, which may be negative. If either of r's dimensions is less than 2*n then an empty rectangle near the center of r will be returned.

func (Rectangle) IntersectSource

func (r Rectangle) Intersect(s Rectangle) Rectangle

Intersect returns the largest rectangle contained by both r and s. If the two rectangles do not overlap then the zero rectangle will be returned.

func (Rectangle) OverlapsSource

func (r Rectangle) Overlaps(s Rectangle) bool

Overlaps reports whether r and s have a non-empty intersection.

func (Rectangle) SizeSource

func (r Rectangle) Size() Point

Size returns r's width and height.

func (Rectangle) StringSource

func (r Rectangle) String() string

String returns a string representation of r like "(3,4)-(6,5)".

func (Rectangle) SubSource

func (r Rectangle) Sub(p Point) Rectangle

Sub returns the rectangle r translated by -p.

func (Rectangle) UnionSource

func (r Rectangle) Union(s Rectangle) Rectangle

Union returns the smallest rectangle that contains both r and s.

type UniformSource

Uniform is an infinite-sized Image of uniform color. It implements the color.Color, color.Model, and Image interfaces.

type Uniform struct {
        C color.Color
}

func NewUniformSource

func NewUniform(c color.Color) *Uniform

func (*Uniform) AtSource

func (c *Uniform) At(x, y int) color.Color

func (*Uniform) BoundsSource

func (c *Uniform) Bounds() Rectangle

func (*Uniform) ColorModelSource

func (c *Uniform) ColorModel() color.Model

func (*Uniform) ConvertSource

func (c *Uniform) Convert(color.Color) color.Color

func (*Uniform) OpaqueSource

func (c *Uniform) Opaque() bool

Opaque scans the entire image and reports whether it is fully opaque.

func (*Uniform) RGBASource

func (c *Uniform) RGBA() (r, g, b, a uint32)

type YCbCrSource

YCbCr is an in-memory image of Y'CbCr colors. There is one Y sample per pixel, but each Cb and Cr sample can span one or more pixels. YStride is the Y slice index delta between vertically adjacent pixels. CStride is the Cb and Cr slice index delta between vertically adjacent pixels that map to separate chroma samples. It is not an absolute requirement, but YStride and len(Y) are typically multiples of 8, and:

For 4:4:4, CStride == YStride/1 && len(Cb) == len(Cr) == len(Y)/1.
For 4:2:2, CStride == YStride/2 && len(Cb) == len(Cr) == len(Y)/2.
For 4:2:0, CStride == YStride/2 && len(Cb) == len(Cr) == len(Y)/4.
For 4:4:0, CStride == YStride/1 && len(Cb) == len(Cr) == len(Y)/2.
For 4:1:1, CStride == YStride/4 && len(Cb) == len(Cr) == len(Y)/4.
For 4:1:0, CStride == YStride/4 && len(Cb) == len(Cr) == len(Y)/8.
type YCbCr struct {
        Y, Cb, Cr      []uint8
        YStride        int
        CStride        int
        SubsampleRatio YCbCrSubsampleRatio
        Rect           Rectangle
}

func NewYCbCrSource

func NewYCbCr(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr

NewYCbCr returns a new YCbCr image with the given bounds and subsample ratio.

func (*YCbCr) AtSource

func (p *YCbCr) At(x, y int) color.Color

func (*YCbCr) BoundsSource

func (p *YCbCr) Bounds() Rectangle

func (*YCbCr) COffsetSource

func (p *YCbCr) COffset(x, y int) int

COffset returns the index of the first element of Cb or Cr that corresponds to the pixel at (x, y).

func (*YCbCr) ColorModelSource

func (p *YCbCr) ColorModel() color.Model

func (*YCbCr) OpaqueSource

func (p *YCbCr) Opaque() bool

func (*YCbCr) SubImageSource

func (p *YCbCr) SubImage(r Rectangle) Image

SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.

func (*YCbCr) YCbCrAtSource

func (p *YCbCr) YCbCrAt(x, y int) color.YCbCr

func (*YCbCr) YOffsetSource

func (p *YCbCr) YOffset(x, y int) int

YOffset returns the index of the first element of Y that corresponds to the pixel at (x, y).

type YCbCrSubsampleRatioSource

YCbCrSubsampleRatio is the chroma subsample ratio used in a YCbCr image.

type YCbCrSubsampleRatio int
const (
        YCbCrSubsampleRatio444 YCbCrSubsampleRatio = iota
        YCbCrSubsampleRatio422
        YCbCrSubsampleRatio420
        YCbCrSubsampleRatio440
        YCbCrSubsampleRatio411
        YCbCrSubsampleRatio410
)

func (YCbCrSubsampleRatio) StringSource

func (s YCbCrSubsampleRatio) String() string

Subdirectories

Name Synopsis
..
color Package color implements a basic color library.
palette Package palette provides standard color palettes.
draw Package draw provides image composition functions.
gif Package gif implements a GIF image decoder and encoder.
jpeg Package jpeg implements a JPEG image decoder and encoder.
png Package png implements a PNG image decoder and encoder.

© Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
https://golang.org/pkg/image/