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
Code:
// 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])
}
Output:
bin red green blue alpha 0x0000-0x0fff: 364 790 7242 0 0x1000-0x1fff: 645 2967 1039 0 0x2000-0x2fff: 1072 2299 979 0 0x3000-0x3fff: 820 2266 980 0 0x4000-0x4fff: 537 1305 541 0 0x5000-0x5fff: 319 962 261 0 0x6000-0x6fff: 322 375 177 0 0x7000-0x7fff: 601 279 214 0 0x8000-0x8fff: 3478 227 273 0 0x9000-0x9fff: 2260 234 329 0 0xa000-0xafff: 921 282 373 0 0xb000-0xbfff: 321 335 397 0 0xc000-0xcfff: 229 388 298 0 0xd000-0xdfff: 260 414 277 0 0xe000-0xefff: 516 428 298 0 0xf000-0xffff: 2785 1899 1772 15450
Example (DecodeConfig)
Code:
reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
config, format, err := image.DecodeConfig(reader)
if err != nil {
log.Fatal(err)
}
fmt.Println("Width:", config.Width, "Height:", config.Height, "Format:", format)
Index
Examples
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 RegisterFormat
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 Alpha
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 NewAlpha
func NewAlpha(r Rectangle) *Alpha
NewAlpha returns a new Alpha image with the given bounds.
func (*Alpha) AlphaAt 1.4
func (p *Alpha) AlphaAt(x, y int) color.Alpha
func (*Alpha) At
func (p *Alpha) At(x, y int) color.Color
func (*Alpha) Bounds
func (p *Alpha) Bounds() Rectangle
func (*Alpha) ColorModel
func (p *Alpha) ColorModel() color.Model
func (*Alpha) Opaque
func (p *Alpha) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Alpha) PixOffset
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) RGBA64At 1.17
func (p *Alpha) RGBA64At(x, y int) color.RGBA64
func (*Alpha) Set
func (p *Alpha) Set(x, y int, c color.Color)
func (*Alpha) SetAlpha
func (p *Alpha) SetAlpha(x, y int, c color.Alpha)
func (*Alpha) SetRGBA64 1.17
func (p *Alpha) SetRGBA64(x, y int, c color.RGBA64)
func (*Alpha) SubImage
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 Alpha16
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 NewAlpha16
func NewAlpha16(r Rectangle) *Alpha16
NewAlpha16 returns a new Alpha16 image with the given bounds.
func (*Alpha16) Alpha16At 1.4
func (p *Alpha16) Alpha16At(x, y int) color.Alpha16
func (*Alpha16) At
func (p *Alpha16) At(x, y int) color.Color
func (*Alpha16) Bounds
func (p *Alpha16) Bounds() Rectangle
func (*Alpha16) ColorModel
func (p *Alpha16) ColorModel() color.Model
func (*Alpha16) Opaque
func (p *Alpha16) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Alpha16) PixOffset
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) RGBA64At 1.17
func (p *Alpha16) RGBA64At(x, y int) color.RGBA64
func (*Alpha16) Set
func (p *Alpha16) Set(x, y int, c color.Color)
func (*Alpha16) SetAlpha16
func (p *Alpha16) SetAlpha16(x, y int, c color.Alpha16)
func (*Alpha16) SetRGBA64 1.17
func (p *Alpha16) SetRGBA64(x, y int, c color.RGBA64)
func (*Alpha16) SubImage
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 CMYK 1.5
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 NewCMYK 1.5
func NewCMYK(r Rectangle) *CMYK
NewCMYK returns a new CMYK image with the given bounds.
func (*CMYK) At 1.5
func (p *CMYK) At(x, y int) color.Color
func (*CMYK) Bounds 1.5
func (p *CMYK) Bounds() Rectangle
func (*CMYK) CMYKAt 1.5
func (p *CMYK) CMYKAt(x, y int) color.CMYK
func (*CMYK) ColorModel 1.5
func (p *CMYK) ColorModel() color.Model
func (*CMYK) Opaque 1.5
func (p *CMYK) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*CMYK) PixOffset 1.5
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) RGBA64At 1.17
func (p *CMYK) RGBA64At(x, y int) color.RGBA64
func (*CMYK) Set 1.5
func (p *CMYK) Set(x, y int, c color.Color)
func (*CMYK) SetCMYK 1.5
func (p *CMYK) SetCMYK(x, y int, c color.CMYK)
func (*CMYK) SetRGBA64 1.17
func (p *CMYK) SetRGBA64(x, y int, c color.RGBA64)
func (*CMYK) SubImage 1.5
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 Config
Config holds an image's color model and dimensions.
type Config struct {
ColorModel color.Model
Width, Height int
}
func DecodeConfig
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 Gray
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 NewGray
func NewGray(r Rectangle) *Gray
NewGray returns a new Gray image with the given bounds.
func (*Gray) At
func (p *Gray) At(x, y int) color.Color
func (*Gray) Bounds
func (p *Gray) Bounds() Rectangle
func (*Gray) ColorModel
func (p *Gray) ColorModel() color.Model
func (*Gray) GrayAt 1.4
func (p *Gray) GrayAt(x, y int) color.Gray
func (*Gray) Opaque
func (p *Gray) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Gray) PixOffset
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) RGBA64At 1.17
func (p *Gray) RGBA64At(x, y int) color.RGBA64
func (*Gray) Set
func (p *Gray) Set(x, y int, c color.Color)
func (*Gray) SetGray
func (p *Gray) SetGray(x, y int, c color.Gray)
func (*Gray) SetRGBA64 1.17
func (p *Gray) SetRGBA64(x, y int, c color.RGBA64)
func (*Gray) SubImage
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 Gray16
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 NewGray16
func NewGray16(r Rectangle) *Gray16
NewGray16 returns a new Gray16 image with the given bounds.
func (*Gray16) At
func (p *Gray16) At(x, y int) color.Color
func (*Gray16) Bounds
func (p *Gray16) Bounds() Rectangle
func (*Gray16) ColorModel
func (p *Gray16) ColorModel() color.Model
func (*Gray16) Gray16At 1.4
func (p *Gray16) Gray16At(x, y int) color.Gray16
func (*Gray16) Opaque
func (p *Gray16) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Gray16) PixOffset
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) RGBA64At 1.17
func (p *Gray16) RGBA64At(x, y int) color.RGBA64
func (*Gray16) Set
func (p *Gray16) Set(x, y int, c color.Color)
func (*Gray16) SetGray16
func (p *Gray16) SetGray16(x, y int, c color.Gray16)
func (*Gray16) SetRGBA64 1.17
func (p *Gray16) SetRGBA64(x, y int, c color.RGBA64)
func (*Gray16) SubImage
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 Image
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 Decode
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 NRGBA
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 NewNRGBA
func NewNRGBA(r Rectangle) *NRGBA
NewNRGBA returns a new NRGBA image with the given bounds.
func (*NRGBA) At
func (p *NRGBA) At(x, y int) color.Color
func (*NRGBA) Bounds
func (p *NRGBA) Bounds() Rectangle
func (*NRGBA) ColorModel
func (p *NRGBA) ColorModel() color.Model
func (*NRGBA) NRGBAAt 1.4
func (p *NRGBA) NRGBAAt(x, y int) color.NRGBA
func (*NRGBA) Opaque
func (p *NRGBA) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*NRGBA) PixOffset
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) RGBA64At 1.17
func (p *NRGBA) RGBA64At(x, y int) color.RGBA64
func (*NRGBA) Set
func (p *NRGBA) Set(x, y int, c color.Color)
func (*NRGBA) SetNRGBA
func (p *NRGBA) SetNRGBA(x, y int, c color.NRGBA)
func (*NRGBA) SetRGBA64 1.17
func (p *NRGBA) SetRGBA64(x, y int, c color.RGBA64)
func (*NRGBA) SubImage
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 NRGBA64
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 NewNRGBA64
func NewNRGBA64(r Rectangle) *NRGBA64
NewNRGBA64 returns a new NRGBA64 image with the given bounds.
func (*NRGBA64) At
func (p *NRGBA64) At(x, y int) color.Color
func (*NRGBA64) Bounds
func (p *NRGBA64) Bounds() Rectangle
func (*NRGBA64) ColorModel
func (p *NRGBA64) ColorModel() color.Model
func (*NRGBA64) NRGBA64At 1.4
func (p *NRGBA64) NRGBA64At(x, y int) color.NRGBA64
func (*NRGBA64) Opaque
func (p *NRGBA64) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*NRGBA64) PixOffset
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) RGBA64At 1.17
func (p *NRGBA64) RGBA64At(x, y int) color.RGBA64
func (*NRGBA64) Set
func (p *NRGBA64) Set(x, y int, c color.Color)
func (*NRGBA64) SetNRGBA64
func (p *NRGBA64) SetNRGBA64(x, y int, c color.NRGBA64)
func (*NRGBA64) SetRGBA64 1.17
func (p *NRGBA64) SetRGBA64(x, y int, c color.RGBA64)
func (*NRGBA64) SubImage
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 NYCbCrA 1.6
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 NewNYCbCrA 1.6
func NewNYCbCrA(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *NYCbCrA
NewNYCbCrA returns a new NYCbCrA image with the given bounds and subsample ratio.
func (*NYCbCrA) AOffset 1.6
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) At 1.6
func (p *NYCbCrA) At(x, y int) color.Color
func (*NYCbCrA) ColorModel 1.6
func (p *NYCbCrA) ColorModel() color.Model
func (*NYCbCrA) NYCbCrAAt 1.6
func (p *NYCbCrA) NYCbCrAAt(x, y int) color.NYCbCrA
func (*NYCbCrA) Opaque 1.6
func (p *NYCbCrA) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*NYCbCrA) RGBA64At 1.17
func (p *NYCbCrA) RGBA64At(x, y int) color.RGBA64
func (*NYCbCrA) SubImage 1.6
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 Paletted
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 NewPaletted
func NewPaletted(r Rectangle, p color.Palette) *Paletted
NewPaletted returns a new Paletted image with the given width, height and palette.
func (*Paletted) At
func (p *Paletted) At(x, y int) color.Color
func (*Paletted) Bounds
func (p *Paletted) Bounds() Rectangle
func (*Paletted) ColorIndexAt
func (p *Paletted) ColorIndexAt(x, y int) uint8
func (*Paletted) ColorModel
func (p *Paletted) ColorModel() color.Model
func (*Paletted) Opaque
func (p *Paletted) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Paletted) PixOffset
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) RGBA64At 1.17
func (p *Paletted) RGBA64At(x, y int) color.RGBA64
func (*Paletted) Set
func (p *Paletted) Set(x, y int, c color.Color)
func (*Paletted) SetColorIndex
func (p *Paletted) SetColorIndex(x, y int, index uint8)
func (*Paletted) SetRGBA64 1.17
func (p *Paletted) SetRGBA64(x, y int, c color.RGBA64)
func (*Paletted) SubImage
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 PalettedImage
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 Point
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.
Deprecated: Use a literal image.Point{} instead.
var ZP Point
func Pt
func Pt(X, Y int) Point
Pt is shorthand for Point{X, Y}.
func (Point) Add
func (p Point) Add(q Point) Point
Add returns the vector p+q.
func (Point) Div
func (p Point) Div(k int) Point
Div returns the vector p/k.
func (Point) Eq
func (p Point) Eq(q Point) bool
Eq reports whether p and q are equal.
func (Point) In
func (p Point) In(r Rectangle) bool
In reports whether p is in r.
func (Point) Mod
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) Mul
func (p Point) Mul(k int) Point
Mul returns the vector p*k.
func (Point) String
func (p Point) String() string
String returns a string representation of p like "(3,4)".
func (Point) Sub
func (p Point) Sub(q Point) Point
Sub returns the vector p-q.
type RGBA
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 NewRGBA
func NewRGBA(r Rectangle) *RGBA
NewRGBA returns a new RGBA image with the given bounds.
func (*RGBA) At
func (p *RGBA) At(x, y int) color.Color
func (*RGBA) Bounds
func (p *RGBA) Bounds() Rectangle
func (*RGBA) ColorModel
func (p *RGBA) ColorModel() color.Model
func (*RGBA) Opaque
func (p *RGBA) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*RGBA) PixOffset
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) RGBA64At 1.17
func (p *RGBA) RGBA64At(x, y int) color.RGBA64
func (*RGBA) RGBAAt 1.4
func (p *RGBA) RGBAAt(x, y int) color.RGBA
func (*RGBA) Set
func (p *RGBA) Set(x, y int, c color.Color)
func (*RGBA) SetRGBA
func (p *RGBA) SetRGBA(x, y int, c color.RGBA)
func (*RGBA) SetRGBA64 1.17
func (p *RGBA) SetRGBA64(x, y int, c color.RGBA64)
func (*RGBA) SubImage
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 RGBA64
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 NewRGBA64
func NewRGBA64(r Rectangle) *RGBA64
NewRGBA64 returns a new RGBA64 image with the given bounds.
func (*RGBA64) At
func (p *RGBA64) At(x, y int) color.Color
func (*RGBA64) Bounds
func (p *RGBA64) Bounds() Rectangle
func (*RGBA64) ColorModel
func (p *RGBA64) ColorModel() color.Model
func (*RGBA64) Opaque
func (p *RGBA64) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*RGBA64) PixOffset
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) RGBA64At 1.4
func (p *RGBA64) RGBA64At(x, y int) color.RGBA64
func (*RGBA64) Set
func (p *RGBA64) Set(x, y int, c color.Color)
func (*RGBA64) SetRGBA64
func (p *RGBA64) SetRGBA64(x, y int, c color.RGBA64)
func (*RGBA64) SubImage
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 RGBA64Image 1.17
RGBA64Image is an Image whose pixels can be converted directly to a color.RGBA64.
type RGBA64Image interface {
// RGBA64At returns the RGBA64 color of the pixel at (x, y). It is
// equivalent to calling At(x, y).RGBA() and converting the resulting
// 32-bit return values to a color.RGBA64, but it can avoid allocations
// from converting concrete color types to the color.Color interface type.
RGBA64At(x, y int) color.RGBA64
Image
} type Rectangle
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.
Deprecated: Use a literal image.Rectangle{} instead.
var ZR Rectangle
func Rect
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) Add
func (r Rectangle) Add(p Point) Rectangle
Add returns the rectangle r translated by p.
func (Rectangle) At 1.5
func (r Rectangle) At(x, y int) color.Color
At implements the Image interface.
func (Rectangle) Bounds 1.5
func (r Rectangle) Bounds() Rectangle
Bounds implements the Image interface.
func (Rectangle) Canon
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) ColorModel 1.5
func (r Rectangle) ColorModel() color.Model
ColorModel implements the Image interface.
func (Rectangle) Dx
func (r Rectangle) Dx() int
Dx returns r's width.
func (Rectangle) Dy
func (r Rectangle) Dy() int
Dy returns r's height.
func (Rectangle) Empty
func (r Rectangle) Empty() bool
Empty reports whether the rectangle contains no points.
func (Rectangle) Eq
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) In
func (r Rectangle) In(s Rectangle) bool
In reports whether every point in r is in s.
func (Rectangle) Inset
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) Intersect
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) Overlaps
func (r Rectangle) Overlaps(s Rectangle) bool
Overlaps reports whether r and s have a non-empty intersection.
func (Rectangle) RGBA64At 1.17
func (r Rectangle) RGBA64At(x, y int) color.RGBA64
RGBA64At implements the RGBA64Image interface.
func (Rectangle) Size
func (r Rectangle) Size() Point
Size returns r's width and height.
func (Rectangle) String
func (r Rectangle) String() string
String returns a string representation of r like "(3,4)-(6,5)".
func (Rectangle) Sub
func (r Rectangle) Sub(p Point) Rectangle
Sub returns the rectangle r translated by -p.
func (Rectangle) Union
func (r Rectangle) Union(s Rectangle) Rectangle
Union returns the smallest rectangle that contains both r and s.
type Uniform
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 NewUniform
func NewUniform(c color.Color) *Uniform
NewUniform returns a new Uniform image of the given color.
func (*Uniform) At
func (c *Uniform) At(x, y int) color.Color
func (*Uniform) Bounds
func (c *Uniform) Bounds() Rectangle
func (*Uniform) ColorModel
func (c *Uniform) ColorModel() color.Model
func (*Uniform) Convert
func (c *Uniform) Convert(color.Color) color.Color
func (*Uniform) Opaque
func (c *Uniform) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*Uniform) RGBA
func (c *Uniform) RGBA() (r, g, b, a uint32)
func (*Uniform) RGBA64At 1.17
func (c *Uniform) RGBA64At(x, y int) color.RGBA64
type YCbCr
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 NewYCbCr
func NewYCbCr(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr
NewYCbCr returns a new YCbCr image with the given bounds and subsample ratio.
func (*YCbCr) At
func (p *YCbCr) At(x, y int) color.Color
func (*YCbCr) Bounds
func (p *YCbCr) Bounds() Rectangle
func (*YCbCr) COffset
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) ColorModel
func (p *YCbCr) ColorModel() color.Model
func (*YCbCr) Opaque
func (p *YCbCr) Opaque() bool
func (*YCbCr) RGBA64At 1.17
func (p *YCbCr) RGBA64At(x, y int) color.RGBA64
func (*YCbCr) SubImage
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) YCbCrAt 1.4
func (p *YCbCr) YCbCrAt(x, y int) color.YCbCr
func (*YCbCr) YOffset
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 YCbCrSubsampleRatio
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) String
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.
http://golang.org/pkg/image/