image

package module
v0.0.3 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Jul 6, 2024 License: BSD-3-Clause Imports: 8 Imported by: 0

README

image

Image, an updated version of the Go standard image libraries

Features

Metadata support

This package supports reading and writing image metadata. This ranges from things as simple as comment blocks in GIF files to ICC color profiles and XMP data.

Size and time safety

Code can set limits on the amount of wall time or memory that encoding or decoding an image can use, which allows code to read files with more safety guarantees than the standard library.

Updated API

A new, unified API exists that allows access to the image metadata, control over encoding and decoding, and the writing of image files with metadata.

The existing API has been maintained for drop-in compatibility with the current standard library.

Deferred image decoding

Image files may be read in without decoding the actual image data, and these deferred images may be written out without incurring the expense and potential image loss of decoding or encoding them. This is useful for code which only wants to examine image metadata, but it also allows programs that want to mutate an image's metadata without mutating the image itself to do so inexpensively and without altering image quality.

This is especially useful for lossy image formats such as jpeg -- deferred image reading and writing allows programs to update jpeg metadata without having to re-encode the image.

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: https://golang.org/doc/articles/image_package.html

Example 
package main

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

	"github.com/rmamba/image"

	// 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"
	_ "github.com/rmamba/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()
	ctx := context.TODO()
	reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
	m, _, err := image.DecodeImage(ctx, 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:    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) 
package main

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

	"github.com/rmamba/image"

	// 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"
	_ "github.com/rmamba/image/jpeg"
)

func main() {
	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)
}

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:

Index

Examples

Constants

This section is empty.

Variables

View Source 
var (
	OptionDecodeImage    = DataDecodeOptions{DecodeData, DiscardData}
	OptionDecodeMetadata = DataDecodeOptions{DiscardData, DecodeData}
)

Sadly Go doesn't support constant structs or this would be a const

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

ErrFormat indicates that decoding encountered an unknown format.

View Source 
var ErrOption = errors.New("image: invalid options")

OptionError indicates that the read or write options provided to a call are invalid.

Functions

func DecodeWithOptions 

func DecodeWithOptions(ctx context.Context, r io.Reader, opts ...ReadOption) (Image, Metadata, string, error)

DecodeWithOptions decodes an image in a registered format, its metadata, and its config. 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.

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.

This function is deprecated, and should only be used by image format decoders that don't support metadata decoding.

func RegisterFormatExtended 

func RegisterFormatExtended(name, magic string, decode func(context.Context, io.Reader, ...ReadOption) (Image, Metadata, error))

RegisterFormatExtended 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, its metadata, and its configuration information.

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 NewAlpha 

func NewAlpha(r Rectangle) *Alpha

NewAlpha returns a new Alpha image with the given bounds.

func (*Alpha) AlphaAt 

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) 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) 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 

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.Alpha16 values.

func NewAlpha16 

func NewAlpha16(r Rectangle) *Alpha16

NewAlpha16 returns a new Alpha16 image with the given bounds.

func (*Alpha16) Alpha16At 

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) 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) 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 

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
}

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

func NewCMYK 

func NewCMYK(r Rectangle) *CMYK

NewCMYK returns a new CMYK image with the given bounds.

func (*CMYK) At 

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

func (*CMYK) Bounds 

func (p *CMYK) Bounds() Rectangle

func (*CMYK) CMYKAt 

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

func (*CMYK) ColorModel 

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

func (*CMYK) Opaque 

func (p *CMYK) Opaque() bool

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

func (*CMYK) PixOffset 

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) Set 

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

func (*CMYK) SetCMYK 

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

func (*CMYK) SubImage 

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 

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

Config holds an image's color model and dimensions.

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.

This function has been deprecated; use DecodeWithOptions or DecodeMetadata and extract the info you need from the metadata returned.

type DamageHandlingOptions 

type DamageHandlingOptions struct {
	// AllowTrailingData, if set to true, means that image file readers
	// won't consider extra data after the end of an image to be an
	// error.
	AllowTrailingData bool
	// SkipDamagedSections indicates that an image decoder should skip
	// damaged data instead of treating it as an error. Image readers
	// will ignore sections with format or checksum issues rather than
	// erroring out, and will skip damaged image data where possible.
	//
	// Even with this set images may still not decode, depending on what
	// kind of damage the image file has.
	SkipDamagedData bool
	// AllowMisorderedSections indicates that image decoders should
	// allow misordered data in image files if at all possible. This
	// does not guarantee that any random ordering of image data is
	// allowed -- image decoders may, for example, stop reading data
	// when the end-of-image marker is encountered (if the image file
	// format has one). Images may decode poorly in this case and
	// integrity or proper decoding isn't guaranteed.
	AllowMisorderedData bool
}

DamageHandlingOptions hold settings that may allow reader code to read damaged or malformed image files. These options should only be provided when code is explicitly trying to read known-damaged image files and should not be used under normal circumstances.

func (DamageHandlingOptions) IsImageReadOption 

func (_ DamageHandlingOptions) IsImageReadOption()

IsImageReadOption is a no-op function which exists to satisfy the ReadOption interface.

type DataDecodeOptions 

type DataDecodeOptions struct {
	// DecodeImage specifies whether the image data should be decoded
	// when an image file is read. Valid options are
	// DefaultDecodeOption, DiscardData, or DecodeData. Default is
	// DecodeData.
	DecodeImage DecodingOption
	// DecodeMetadata specifies whether the image metadata should be
	// decoded when an image is read. Valid options are
	// DefaultDecodeData, DiscardData, DeferData, and
	// DecodeData. Default is DeferData.
	DecodeMetadata DecodingOption
}

DataDecodeOptions notes which

func (DataDecodeOptions) IsImageReadOption 

func (_ DataDecodeOptions) IsImageReadOption()

IsImageReadOption is a no-op function which exists to satisfy the ReadOption interface.

type DecodingOption 

type DecodingOption int

DecodingOption notes when and if data should be decoded. 

const (
	// DefaultDecodeOption means the data should be read, ignored, or
	// deferred as appropriate for the data item.
	DefaultDecodeOption DecodingOption = iota
	// DiscardData indicates the data shouldn't be decoded at all.
	DiscardData
	// DeferData means as much of the data decoding should be deferred
	// as possible until it is used by the calling program Not all
	// decoding can be deferred.
	DeferData
	// DecodeData meads the data should be decoded as the image file is
	// read.
	DecodeData
)

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 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 

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) 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) 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 

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 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 

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) 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) 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 

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.

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. (DEPRECATED)

func DecodeImage 

func DecodeImage(ctx context.Context, r io.Reader, opts ...ReadOption) (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 ImageTransformOptions 

type ImageTransformOptions struct {
	// RotationTransform controls how the image transform metadata
	// should be applied when reading an image. By defaul the image has
	// no rotation transformations applied.
	RotationTransform TransformOption
	// ColorTransform controls how the color metadata should be applied
	// when reading an image. By default the returned image has no color
	// transformations applied.
	ColorTransform TransformOption
	// GammaTransform controls how the gamma metadata should be applied
	// when reading an image. By default the returned image has no gamma
	// transformations applied.
	GammaTransform TransformOption
}

ImageTransformOptions controls how the image transformation metadata embedded in an image file should be interpreted and applied.

For example, when you take a picture with your phone in landscape mode the image file will be saved in portrait orientation (that is, as if your phone was upright) with a metadata annotation noting the image should be rotated 90 degrees. If you read that image without reading the metadata then the image will look as if it's on its side. If you set RotationTransform to ForwardImageTransform, however, the image will be in its proper orientation.

func (ImageTransformOptions) IsImageReadOption 

func (_ ImageTransformOptions) IsImageReadOption()

IsImageReadOption is a no-op finction which exists to satisfy the ReadOption interface.

type LimitOptions 

type LimitOptions struct {
	// MaxImageSize is the maximum size, in bytes, a decoded image can
	// take. Images that decode larger than this will throw an error.
	MaxImageSize int
	// MaxMetadataSize is the maximum size, in bytes, decoded metadata
	// can take. Images with metadata larger than this will throw an
	// error.
	MaxMetadataSize int
}

LimitOptions holds limits for the standard read options.

func (LimitOptions) IsImageReadOption 

func (_ LimitOptions) IsImageReadOption()

IsImageReadOption is a no-op function which exists to satisfy the ReadOption interface.

func (LimitOptions) IsImageWriteOption 

func (_ LimitOptions) IsImageWriteOption()

IsImaegWriteOption allows a LimitOptions struct get passed when writing out an image to allow size limits to be placed on the output file.

type Metadata 

type Metadata interface {
	// ImageMetadataFormat returns the image format for the
	// metadata. This should be the plain name of the format -- for
	// example, "jpeg", "gif", or "png" for jpeg, gif, or png image
	// metadata respectively.
	//
	// This is also appropriate for shared metadata structures, such as
	// XMP or EXIF, which can be applied to multiple image types.
	ImageMetadataFormat() string
	GetConfig() Config
}

Metadata is image-encoding-specific metadata which can be attached to an image.

func DecodeMetadata 

func DecodeMetadata(ctx context.Context, r io.Reader, opts ...ReadOption) (Metadata, string, error)

Decode decodes the metadata for 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.

Note that if you need both the image and the metadata for an image it's more efficient to call DecodeWithOption and extract both simiultaneously.

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 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 

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) 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) 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 

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 

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 

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) 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) 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 

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

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.

func NewNYCbCrA 

func NewNYCbCrA(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *NYCbCrA

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

func (*NYCbCrA) AOffset 

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 

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

func (*NYCbCrA) ColorModel 

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

func (*NYCbCrA) NYCbCrAAt 

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

func (*NYCbCrA) Opaque 

func (p *NYCbCrA) Opaque() bool

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

func (*NYCbCrA) SubImage 

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 

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 

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) 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) 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 

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 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 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.

Deprecated: Use a literal image.Point{} instead.

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 

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 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) RGBAAt 

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) 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 

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 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 

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 ReadOption 

type ReadOption interface {
	IsImageReadOption()
}

ReadOption is an option that controls how an image file is read. There are multiple different kinds of read options and individual image formats may declare their own as necessary.

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.

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. 

var ZR Rectangle

ZR is the zero Rectangle.

Deprecated: Use a literal image.Rectangle{} instead.

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 

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

At implements the Image interface.

func (Rectangle) Bounds 

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 

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) 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 TransformOption 

type TransformOption int
const (
	// ForwardImageTransform indicates the raw image data has not had
	// the metadata transformation applied, and that transformation
	// should be applied when the image is read.
	ForwardImageTransform TransformOption = 1
	// ReverseImageTransform indicates the raw image has already had the
	// metadata transform applied, and that transformation should be
	// reversed when the image is read.
	ReverseImageTransform TransformOption = -1
	// NoImageTransform indicates that the raw image data should not be
	// transformed.
	NoImageTransform TransformOption = 0
)

type Uniform 

type Uniform struct {
	C color.Color
}

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

func NewUniform 

func NewUniform(c color.Color) *Uniform

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)

type WriteOption 

type WriteOption interface {
	IsImageWriteOption()
}

WriteOption holds options for writing image data out. Each image package may implement its own write options but should support the core image package's write options.

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.
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.

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) 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 

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 

type YCbCrSubsampleRatio int

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

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

func (YCbCrSubsampleRatio) String 

func (s YCbCrSubsampleRatio) String() string

Source Files

View all Source files

Directories

Path Synopsis
Package color implements a basic color library.
 Package color implements a basic color library.
palette
Package palette provides standard color palettes.
 Package palette provides standard color palettes.
Package draw provides image composition functions.
 Package draw provides image composition functions.
example
forgiving
This program demonstrates loading in a potentally broken image to try and extract as much information as possible from it.
 This program demonstrates loading in a potentally broken image to try and extract as much information as possible from it.
metadata
This program takes an image file as an argument and dumps out some of the metadata information contained inside it.
 This program takes an image file as an argument and dumps out some of the metadata information contained inside it.
png_no_exif
png_with_exif
spacebound
This program demonstrates reading an image file with a bounded maximum amount of memory allowed for the image.
 This program demonstrates reading an image file with a bounded maximum amount of memory allowed for the image.
timeout
This program demonstrates reading an image file with a context that has a timeout set.
 This program demonstrates reading an image file with a context that has a timeout set.
transform
Transform shows how to load in an image and apply the transforms indicated in its metadata.
 Transform shows how to load in an image and apply the transforms indicated in its metadata.
Package gif implements a GIF image decoder and encoder.
 Package gif implements a GIF image decoder and encoder.
internal
imageutil
Package imageutil contains code shared by image-related packages.
 Package imageutil contains code shared by image-related packages.
Package jpeg implements a JPEG image decoder and encoder.
 Package jpeg implements a JPEG image decoder and encoder.
exif
Package exif encodes and decodes EXIF format image metadata.
 Package exif encodes and decodes EXIF format image metadata.
icc
Package icc encodes and decodes ICC color profiles.
 Package icc encodes and decodes ICC color profiles.
xmp
Package xmp encodes and decodes XMP format image metadata.
 Package xmp encodes and decodes XMP format image metadata.
Package png implements a PNG image decoder and encoder.
 Package png implements a PNG image decoder and encoder.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.