Documentation ¶
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: http://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 = ` /9j/4AAQSkZJRgABAQIAHAAcAAD/2wBDABALDA4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdA SFxOQERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVGC8aGi9jQjhCY2NjY2NjY2NjY2Nj Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2P/wAARCABnAJYDASIAAhEBAxEB/8QA HwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQRBRIh MUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RFRkdISUpTVFVW V1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ipqrKztLW2t7i5usLDxMXG x8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEAAwEBAQEBAQEBAQAAAAAAAAECAwQF BgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAV YnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOE hYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq 8vP09fb3+Pn6/9oADAMBAAIRAxEAPwDlwKMD0pwzSiuK57QzGDxS7D6in8Y5ximnAPUfSlcq4m3ilUYp 2OKXHvRcVxnTtS7c07HNFK4DQPakC4PNOA+tOx70XAjK/So5gBGP94fzqfvUVx/qxx/EP51UXqRP4WSE cmgjilP3jSEZqS0IO/NGDnpUiocDg/McDjvV6HTPOdVWYgsM5KcfzzQ2JySM2jp6VYu7SWzmMUwG4cgj kMPUVBjjtTGtRu0Zopw+lFFxhinrGzuqqMsxAA9yaXFSRv5cqSEcIwYj6GpuZ30O30fSLKzhUpbpNMv3 5XGTn29BV28jt7pPLuIVljPBBFVreYx+VbqAjycgt3x14zRcNOxGyVFHQkIc/wA61exyKLbuzjdZ046d ftEuTEw3Rk9SPT8P8Kpbea3tchbyVae4JkjbbGpGdwOM89Af6ViFTWUtGdcXoM2+woK1JtpNtTcoZt+l Jt7ZqTbRtouFyPFRXI/c9D94fzqzioLsfuD/ALw/nVReqIn8LJCOTSY+tSMOTmkIpXLRu+F0t5pJxPHG wjjUAuBjJJz1+laD6Pai+WaK9SBX6puzn6ZP+NV/Dkdtc6ZNbyAFwxLAHDYPv6VoQ21nPNEEiQGEFRtk Gf0NaWTOeW7Of8QwGG4MRZnEbYXPJwRnOR0zWNXW+KrqBLUWi5EjbWCgcAA9c/gRXKYqZaGlK/LqMH0F FLtHvRSNiYD2pSDTgpp6p0ywUHoTULXYxcktzrdCf7Xo8LP/AKyEmMNjJ46dfbFWJ5TDGNwB9lFUvDV9 YrbfYGbyrjcWG88S57g+vtV26ZIvMlumKwwjLZ6V0WfU54yTvYwtbubea2WNWbzg4bYQeBgj8OtYeKhj u4y2HQxqxOD1xzxmrWAQCCGB6EGsaikndmsJxeiYzBo280/Z7UbayuaXGY5oIp+2lx9KLjIsVDeD/Rj/ ALy/zq1t96r3y4tT/vL/ADq4P3kRP4WSleTSFKkkKoCW4GaqNcMxIjXj1pxjKT0FKrGC1Nrw3vGrKkYz 5kTAr6455/HH510UdwPtRgWCbzF5+YYUf4Vwun39xpmoR3qASMmQUJwGU9Rnt/8AWrpbrxhb8/ZdOmaQ gAGZwFH5ZJrpVKVlY5ZYhN6kXiu2eO/ikZlIljAAB5yM549OawSOOlPuLqe+umuLqTfM4OSOAo7ADsKh hl/cRsTuJHPv7mlKi3sVTxNtGP20VJhThgSQaK52mnZnUqsWrpkyeUrr5pABOAPU1AGaXUCWJISHGPfP P8qL7BiKnsMg46H3qrbzupbj5mPTPTpXVSglG551SpzSsXJ4/MBUgYIxyKpySyGBYJriV1D7kRpCVH4V bSeNJ4xchni3DeqnBI+td7F4b0mKIRjT45VbktJlzk455+n6VtYzv2PNwFZWBHBGKVJDGVC54/nXQeMN NttLNkba1jgWVWDmM8bhg4/nzXLSSbXVj6fyNKUdNRp21RtIRJGrjuM0u3FQ2DbodvcEkfQmrW2vLqLl k0ejCXNFMj2/jQV9qkxSYNRcsZiq2oI32N2CkhWXJxwOe9XMcVt6hoPn6dFaW0wgRpNzvKDlz6+/0rai ryv2Jm9LHJai+ZRGCBjnr71ErdAxAY9B611t1Y2cunbbaOQ3FvKZI3UqGlZMbiWwfcfhV231iwvLSM3U lt5Uq52TuZG+hGMA12xXJGxxzjzybOQtNOvb5j9ktZJhnBIHyg+5PFX38JayqK/2eLJIBUTgkDA9q7ex itrSHFpGsUbndhRgc+g7VNIyfZJAoJZUbb3I46CtFJMylBo8sdWhmYMuCnylc9wef5VUT7+1chc5NS7h sUZO5RtIPUH3pkBDOxxxmqM9TQtn+WilhHfHaik43KTG3Z4IyPyrNVjGCsZ+dmwv6V3cXhSG8sYpJLud JJIwxChdoJGcYx/Wkg8DafA4knvLiQr/ALqj+VQpKw3FtnFFfvbiSMgZJ6/jXp2n3d9cQRBTFsKD96EP oOxPU/8A68VVtbbRtMVntbePKDLTSHJH/Aj/AEqHTvE66rq72VugMMcbSGTnL4wMAfjT5n0HyW3L+s6b baxaJBdzN+7bcrxkAhun0rz3VNCv7e7lgigknWI43xLu6jjIHTjtXqfkpPGVYsBkghTikgsYIN/lhgXb cxLkknp/ShczQ7xtY8vtEmhkj8yGRBuCnehUcnHcVtmwfJ/fQ8e7f/E12txZW91C0U6b42xlST2OR/Ko Bo1gM/uW55/1jf41nOipu7LhV5FZHIGzI6zwj/vr/Ck+yr3uYf8Ax7/CutbQdMb71tn/ALaN/jSf8I/p X/PoP++2/wAan6rAr6wzkWt0II+1Rc/7Lf4Vd1eeCSKBbdZDdShYoiZNoyfY10P/AAj2lf8APmP++2/x oPh/SjKspsozIuNrZORjp3qo0FHYPb3OZt7ae3SzjuItsiRSAgnccl/UA+3Q1yNjKLR4ZZYY5VD7tkv3 WwO/+e1evPp9nI257aJm6bioz1z1+tY+s6Hplnot9PbWMMcqwOFcLyOO1bJWMZSTOPHi+9w3mosrlyd2 9lCj02g9P/1e9a3hzxAbl2ikZRcdQueHHt7j864Y8Z4I4oRzG6urFWU5BHBB7HNJxTFGbR6he6Vpmtgm eLy5zwZI/lb8fX8azIvBUUTHdfSFP4QsYB/HNZ+k+KEnRY75hHOvAk6K/v7H9K6yyvlnQBmDZ6GsnzR0 N0oy1RzOtaN/Y1tHNFO06u+zYy4I4Jzx9KKveJblXuordSGES5b6n/62PzorKVdp2LjQTVyWz8UWEWlq jSgyxfJt6EgdDzWTdeLIZGO7zHI/hVajGmWWP+PWL8qwlAIURrhpMAHHJA71pRcZrToZzcoEuo6heakA GHk245CZ6/X1qPTLq40q+W5t2QybSpDAkEEc55/zilk5k2r91eKhLDzWz2rpsczbbuemeD76fUNG865I MiysmQMZAAwa3a5j4ftu0ByP+fh/5CulkLLG7INzhSVHqe1Fh3uOoqn9qQQxyhndmHIxwOmSR2xQ13KD KoiBZOV9JBnt707MVy5RWdNdy7wRGf3bfMinnO1jg+vY03WXLaJO3mhQ20b0zwpYf0qlG7S7icrJs08U VwumgC+YiQyeVtZH567hzj8aSL949oGhE/2v5pJCDkksQwBHC4/+vXQ8LZ2uYxxCavY7us/xCcaBfn0h b+VP0bnSrb94ZMJgOecj1rl/GfidUE2k2gy5+SeQjgA/wj3rlas2jdao48qrjLAGkSKPk4Gc1WMj92I+ lIJnU8OfxPWo5inBokmtQTmM4OOh71b0q6vbFmWCbaxHyqQGAP0PT8KhSTzVyo5ocSKA5VfTOTmqsmRd pl99XjPzThzK3zOeOSeveirNmkgg/fIpYsTkYORxRXmzlTjJqx6EVUcU7mhkKCzdAK59QI9zYxtG1fYU UVtgtmY4nZEa8Ak9aqFv3rfSiiu1nMeifDv/AJF+T/r4f+QrqqKKQwzQenNFFMCOKFIgNuThdoJ5OPSk ubeK6t3gnXdG4wwziiii/UTKMOg6dbzJLFE4dSCP3rEdeOM8805tDsGMvySgSsS6rM6gk9eAcUUVftZt 3uyVGNthuq3Eei6DK8H7sRR7YuMgHtXkc8rzTNLM26RyWY+p70UVnLY0iEsUipG7rhZBlDkc1HgYoorM 0HwyBXGeRjmrcUhMg2ghezd//rUUVcTKW5s2jZtY/QDaOKKKK8ip8bPRj8KP/9k= `
Output: bin red green blue alpha 0x0000-0x0fff: 353 759 7228 0 0x1000-0x1fff: 629 2944 1036 0 0x2000-0x2fff: 1075 2319 984 0 0x3000-0x3fff: 838 2291 988 0 0x4000-0x4fff: 540 1302 542 0 0x5000-0x5fff: 319 971 263 0 0x6000-0x6fff: 316 377 178 0 0x7000-0x7fff: 581 280 216 0 0x8000-0x8fff: 3457 228 274 0 0x9000-0x9fff: 2294 237 334 0 0xa000-0xafff: 938 283 370 0 0xb000-0xbfff: 322 338 401 0 0xc000-0xcfff: 229 386 295 0 0xd000-0xdfff: 263 416 281 0 0xe000-0xefff: 538 433 312 0 0xf000-0xffff: 2758 1886 1748 15450
Index ¶
- Variables
- func RegisterFormat(name, magic string, decode func(io.Reader) (Image, error), ...)
- type Alpha
- func (p *Alpha) At(x, y int) color.Color
- func (p *Alpha) Bounds() Rectangle
- func (p *Alpha) ColorModel() color.Model
- func (p *Alpha) Opaque() bool
- func (p *Alpha) PixOffset(x, y int) int
- func (p *Alpha) Set(x, y int, c color.Color)
- func (p *Alpha) SetAlpha(x, y int, c color.Alpha)
- func (p *Alpha) SubImage(r Rectangle) Image
- type Alpha16
- func (p *Alpha16) At(x, y int) color.Color
- func (p *Alpha16) Bounds() Rectangle
- func (p *Alpha16) ColorModel() color.Model
- func (p *Alpha16) Opaque() bool
- func (p *Alpha16) PixOffset(x, y int) int
- func (p *Alpha16) Set(x, y int, c color.Color)
- func (p *Alpha16) SetAlpha16(x, y int, c color.Alpha16)
- func (p *Alpha16) SubImage(r Rectangle) Image
- type Config
- type Gray
- func (p *Gray) At(x, y int) color.Color
- func (p *Gray) Bounds() Rectangle
- func (p *Gray) ColorModel() color.Model
- func (p *Gray) Opaque() bool
- func (p *Gray) PixOffset(x, y int) int
- func (p *Gray) Set(x, y int, c color.Color)
- func (p *Gray) SetGray(x, y int, c color.Gray)
- func (p *Gray) SubImage(r Rectangle) Image
- type Gray16
- func (p *Gray16) At(x, y int) color.Color
- func (p *Gray16) Bounds() Rectangle
- func (p *Gray16) ColorModel() color.Model
- func (p *Gray16) Opaque() bool
- func (p *Gray16) PixOffset(x, y int) int
- func (p *Gray16) Set(x, y int, c color.Color)
- func (p *Gray16) SetGray16(x, y int, c color.Gray16)
- func (p *Gray16) SubImage(r Rectangle) Image
- type Image
- type NRGBA
- func (p *NRGBA) At(x, y int) color.Color
- func (p *NRGBA) Bounds() Rectangle
- func (p *NRGBA) ColorModel() color.Model
- func (p *NRGBA) Opaque() bool
- func (p *NRGBA) PixOffset(x, y int) int
- func (p *NRGBA) Set(x, y int, c color.Color)
- func (p *NRGBA) SetNRGBA(x, y int, c color.NRGBA)
- func (p *NRGBA) SubImage(r Rectangle) Image
- type NRGBA64
- func (p *NRGBA64) At(x, y int) color.Color
- func (p *NRGBA64) Bounds() Rectangle
- func (p *NRGBA64) ColorModel() color.Model
- func (p *NRGBA64) Opaque() bool
- func (p *NRGBA64) PixOffset(x, y int) int
- func (p *NRGBA64) Set(x, y int, c color.Color)
- func (p *NRGBA64) SetNRGBA64(x, y int, c color.NRGBA64)
- func (p *NRGBA64) SubImage(r Rectangle) Image
- type Paletted
- func (p *Paletted) At(x, y int) color.Color
- func (p *Paletted) Bounds() Rectangle
- func (p *Paletted) ColorIndexAt(x, y int) uint8
- func (p *Paletted) ColorModel() color.Model
- func (p *Paletted) Opaque() bool
- func (p *Paletted) PixOffset(x, y int) int
- func (p *Paletted) Set(x, y int, c color.Color)
- func (p *Paletted) SetColorIndex(x, y int, index uint8)
- func (p *Paletted) SubImage(r Rectangle) Image
- type PalettedImage
- type Point
- type RGBA
- func (p *RGBA) At(x, y int) color.Color
- func (p *RGBA) Bounds() Rectangle
- func (p *RGBA) ColorModel() color.Model
- func (p *RGBA) Opaque() bool
- func (p *RGBA) PixOffset(x, y int) int
- func (p *RGBA) Set(x, y int, c color.Color)
- func (p *RGBA) SetRGBA(x, y int, c color.RGBA)
- func (p *RGBA) SubImage(r Rectangle) Image
- type RGBA64
- func (p *RGBA64) At(x, y int) color.Color
- func (p *RGBA64) Bounds() Rectangle
- func (p *RGBA64) ColorModel() color.Model
- func (p *RGBA64) Opaque() bool
- func (p *RGBA64) PixOffset(x, y int) int
- func (p *RGBA64) Set(x, y int, c color.Color)
- func (p *RGBA64) SetRGBA64(x, y int, c color.RGBA64)
- func (p *RGBA64) SubImage(r Rectangle) Image
- type Rectangle
- func (r Rectangle) Add(p Point) Rectangle
- func (r Rectangle) Canon() Rectangle
- func (r Rectangle) Dx() int
- func (r Rectangle) Dy() int
- func (r Rectangle) Empty() bool
- func (r Rectangle) Eq(s Rectangle) bool
- func (r Rectangle) In(s Rectangle) bool
- func (r Rectangle) Inset(n int) Rectangle
- func (r Rectangle) Intersect(s Rectangle) Rectangle
- func (r Rectangle) Overlaps(s Rectangle) bool
- func (r Rectangle) Size() Point
- func (r Rectangle) String() string
- func (r Rectangle) Sub(p Point) Rectangle
- func (r Rectangle) Union(s Rectangle) Rectangle
- type Uniform
- type YCbCr
- type YCbCrSubsampleRatio
Examples ¶
Constants ¶
This section is empty.
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) )
var ErrFormat = errors.New("image: unknown format")
ErrFormat indicates that decoding encountered an unknown format.
Functions ¶
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.
Types ¶
type Alpha ¶
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 }
Alpha is an in-memory image whose At method returns color.Alpha values.
func (*Alpha) ColorModel ¶
type Alpha16 ¶
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 }
Alpha16 is an in-memory image whose At method returns color.Alpha64 values.
func NewAlpha16 ¶
NewAlpha16 returns a new Alpha16 with the given bounds.
func (*Alpha16) ColorModel ¶
type Config ¶
Config holds an image's color model and dimensions.
func DecodeConfig ¶
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 ¶
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 }
Gray is an in-memory image whose At method returns color.Gray values.
func (*Gray) ColorModel ¶
type Gray16 ¶
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 }
Gray16 is an in-memory image whose At method returns color.Gray16 values.
func (*Gray16) ColorModel ¶
type Image ¶
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 }
Image is a finite rectangular grid of color.Color values taken from a color model.
type NRGBA ¶
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 }
NRGBA is an in-memory image whose At method returns color.NRGBA values.
func (*NRGBA) ColorModel ¶
type NRGBA64 ¶
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 }
NRGBA64 is an in-memory image whose At method returns color.NRGBA64 values.
func NewNRGBA64 ¶
NewNRGBA64 returns a new NRGBA64 with the given bounds.
func (*NRGBA64) ColorModel ¶
type Paletted ¶
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 }
Paletted is an in-memory image of uint8 indices into a given palette.
func NewPaletted ¶
NewPaletted returns a new Paletted with the given width, height and palette.
func (*Paletted) ColorIndexAt ¶
func (*Paletted) ColorModel ¶
func (*Paletted) PixOffset ¶
PixOffset returns the index of the first element of Pix that corresponds to the pixel at (x, y).
func (*Paletted) SetColorIndex ¶
type PalettedImage ¶
type PalettedImage interface { // ColorIndexAt returns the palette index of the pixel at (x, y). ColorIndexAt(x, y int) uint8 Image }
PalettedImage is an image whose colors may come from a limited palette. If m is a PalettedImage and m.ColorModel() returns a PalettedColorModel p, then m.At(x, y) should be equivalent to p[m.ColorIndexAt(x, y)]. If m's color model is not a PalettedColorModel, then ColorIndexAt's behavior is undefined.
type Point ¶
type Point struct {
X, Y int
}
A Point is an X, Y coordinate pair. The axes increase right and down.
var ZP Point
ZP is the zero Point.
func (Point) Mod ¶
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.
type RGBA ¶
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 }
RGBA is an in-memory image whose At method returns color.RGBA values.
func (*RGBA) ColorModel ¶
type RGBA64 ¶
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 }
RGBA64 is an in-memory image whose At method returns color.RGBA64 values.
func (*RGBA64) ColorModel ¶
type Rectangle ¶
type Rectangle struct {
Min, Max Point
}
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.
var ZR Rectangle
ZR is the zero Rectangle.
func (Rectangle) Canon ¶
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) Inset ¶
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 ¶
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.
type Uniform ¶
Uniform is an infinite-sized Image of uniform color. It implements the color.Color, color.Model, and Image interfaces.
func NewUniform ¶
func (*Uniform) ColorModel ¶
type YCbCr ¶
type YCbCr struct {
Y, Cb, Cr []uint8
YStride int
CStride int
SubsampleRatio YCbCrSubsampleRatio
Rect Rectangle
}
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.
func NewYCbCr ¶
func NewYCbCr(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr
NewYCbCr returns a new YCbCr with the given bounds and subsample ratio.
func (*YCbCr) COffset ¶
COffset returns the index of the first element of Cb or Cr that corresponds to the pixel at (x, y).
func (*YCbCr) ColorModel ¶
type YCbCrSubsampleRatio ¶
type YCbCrSubsampleRatio int
YCbCrSubsampleRatio is the chroma subsample ratio used in a YCbCr image.
const ( YCbCrSubsampleRatio444 YCbCrSubsampleRatio = iota YCbCrSubsampleRatio422 YCbCrSubsampleRatio420 YCbCrSubsampleRatio440 )
func (YCbCrSubsampleRatio) String ¶
func (s YCbCrSubsampleRatio) String() string
Directories ¶
Path | Synopsis |
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Package color implements a basic color library.
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Package color implements a basic color library. |
Package draw provides image composition functions.
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Package draw provides image composition functions. |
Package gif implements a GIF image decoder and encoder.
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Package gif implements a GIF image decoder and encoder. |
Package jpeg implements a JPEG image decoder and encoder.
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Package jpeg implements a JPEG image decoder and encoder. |
Package png implements a PNG image decoder and encoder.
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Package png implements a PNG image decoder and encoder. |