package png

Import Path
	image/png (on golang.org and go.dev)

Dependency Relation
	imports 10 packages, and imported by 0 packages

Involved Source Files paeth.go Package png implements a PNG image decoder and encoder. The PNG specification is at https://www.w3.org/TR/PNG/. writer.go
Code Examples package main import ( "encoding/base64" "fmt" "image/color" "image/png" "io" "log" "strings" ) const gopher = `iVBORw0KGgoAAAANSUhEUgAAAEsAAAA8CAAAAAALAhhPAAAFfUlEQVRYw62XeWwUVRzHf2+OPbo9d7tsWyiyaZti6eWGAhISoIGKECEKCAiJJkYTiUgTMYSIosYYBBIUIxoSPIINEBDi2VhwkQrVsj1ESgu9doHWdrul7ba73WNm3vOPtsseM9MdwvvrzTs+8/t95ze/33sI5BqiabU6m9En8oNjduLnAEDLUsQXFF8tQ5oxK3vmnNmDSMtrncks9Hhtt/qeWZapHb1ha3UqYSWVl2ZmpWgaXMXGohQAvmeop3bjTRtv6SgaK/Pb9/bFzUrYslbFAmHPp+3WhAYdr+7GN/YnpN46Opv55VDsJkoEpMrY/vO2BIYQ6LLvm0ThY3MzDzzeSJeeWNyTkgnIE5ePKsvKlcg/0T9QMzXalwXMlj54z4c0rh/mzEfr+FgWEz2w6uk8dkzFAgcARAgNp1ZYef8bH2AgvuStbc2/i6CiWGj98y2tw2l4FAXKkQBIf+exyRnteY83LfEwDQAYCoK+P6bxkZm/0966LxcAAILHB56kgD95PPxltuYcMtFTWw/FKkY/6Opf3GGd9ZF+Qp6mzJxzuRSractOmJrH1u8XTvWFHINNkLQLMR+XHXvfPPHw967raE1xxwtA36IMRfkAAG29/7mLuQcb2WOnsJReZGfpiHsSBX81cvMKywYZHhX5hFPtOqPGWZCXnhWGAu6lX91ElKXSalcLXu3UaOXVay57ZSe5f6Gpx7J2MXAsi7EqSp09b/MirKSyJfnfEEgeDjl8FgDAfvewP03zZ+AJ0m9aFRM8eEHBDRKjfcreDXnZdQuAxXpT2NRJ7xl3UkLBhuVGU16gZiGOgZmrSbRdqkILuL/yYoSXHHkl9KXgqNu3PB8oRg0geC5vFmLjad6mUyTKLmF3OtraWDIfACyXqmephaDABawfpi6tqqBZytfQMqOz6S09iWXhktrRaB8Xz4Yi/8gyABDm5NVe6qq/3VzPrcjELWrebVuyY2T7ar4zQyybUCtsQ5Es1FGaZVrRVQwAgHGW2ZCRZshI5bGQi7HesyE972pOSeMM0dSktlzxRdrlqb3Osa6CCS8IJoQQQgBAbTAa5l5epO34rJszibJI8rxLfGzcp1dRosutGeb2VDNgqYrwTiPNsLxXiPi3dz7LiS1WBRBDBOnqEjyy3aQb+/bLiJzz9dIkscVBBLxMfSEac7kO4Fpkngi0ruNBeSOal+u8jgOuqPz12nryMLCniEjtOOOmpt+KEIqsEdocJjYXwrh9OZqWJQyPCTo67LNS/TdxLAv6R5ZNK9npEjbYdT33gRo4o5oTqR34R+OmaSzDBWsAIPhuRcgyoteNi9gF0KzNYWVItPf2TLoXEg+7isNC7uJkgo1iQWOfRSP9NR11RtbZZ3OMG/VhL6jvx+J1m87+RCfJChAtEBQkSBX2PnSiihc/Twh3j0h7qdYQAoRVsRGmq7HU2QRbaxVGa1D6nIOqaIWRjyRZpHMQKWKpZM5feA+lzC4ZFultV8S6T0mzQGhQohi5I8iw+CsqBSxhFMuwyLgSwbghGb0AiIKkSDmGZVmJSiKihsiyOAUs70UkywooYP0bii9GdH4sfr1UNysd3fUyLLMQN+rsmo3grHl9VNJHbbwxoa47Vw5gupIqrZcjPh9R4Nye3nRDk199V+aetmvVtDRE8/+cbgAAgMIWGb3UA0MGLE9SCbWX670TDy1y98c3D27eppUjsZ6fql3jcd5rUe7+ZIlLNQny3Rd+E5Tct3WVhTM5RBCEdiEK0b6B+/ca2gYU393nFj/n1AygRQxPIUA043M42u85+z2SnssKrPl8Mx76NL3E6eXc3be7OD+H4WHbJkKI8AU8irbITQjZ+0hQcPEgId/Fn/pl9crKH02+5o2b9T/eMx7pKoskYgAAAABJRU5ErkJggg==` // gopherPNG creates an io.Reader by decoding the base64 encoded image data string in the gopher constant. func gopherPNG() io.Reader { return base64.NewDecoder(base64.StdEncoding, strings.NewReader(gopher)) } func main() { // This example uses png.Decode which can only decode PNG images. // Consider using the general image.Decode as it can sniff and decode any registered image format. img, err := png.Decode(gopherPNG()) if err != nil { log.Fatal(err) } levels := []string{" ", "░", "▒", "▓", "█"} for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ { for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ { c := color.GrayModel.Convert(img.At(x, y)).(color.Gray) level := c.Y / 51 // 51 * 5 = 255 if level == 5 { level-- } fmt.Print(levels[level]) } fmt.Print("\n") } } package main import ( "image" "image/color" "image/png" "log" "os" ) func main() { const width, height = 256, 256 // Create a colored image of the given width and height. img := image.NewNRGBA(image.Rect(0, 0, width, height)) for y := 0; y < height; y++ { for x := 0; x < width; x++ { img.Set(x, y, color.NRGBA{ R: uint8((x + y) & 255), G: uint8((x + y) << 1 & 255), B: uint8((x + y) << 2 & 255), A: 255, }) } } f, err := os.Create("image.png") if err != nil { log.Fatal(err) } if err := png.Encode(f, img); err != nil { f.Close() log.Fatal(err) } if err := f.Close(); err != nil { log.Fatal(err) } }
Package-Level Type Names (total 6)
/* sort by: | */
CompressionLevel indicates the compression level. const BestCompression const BestSpeed const DefaultCompression const NoCompression
Encoder configures encoding PNG images. BufferPool optionally specifies a buffer pool to get temporary EncoderBuffers when encoding an image. CompressionLevel CompressionLevel Encode writes the Image m to w in PNG format.
EncoderBuffer holds the buffers used for encoding PNG images. func EncoderBufferPool.Get() *EncoderBuffer func EncoderBufferPool.Put(*EncoderBuffer)
EncoderBufferPool is an interface for getting and returning temporary instances of the EncoderBuffer struct. This can be used to reuse buffers when encoding multiple images. ( T) Get() *EncoderBuffer ( T) Put(*EncoderBuffer)
A FormatError reports that the input is not a valid PNG. ( T) Error() string T : error
An UnsupportedError reports that the input uses a valid but unimplemented PNG feature. ( T) Error() string T : error
Package-Level Functions (total 3)
Decode reads a PNG image from r and returns it as an image.Image. The type of Image returned depends on the PNG contents.
DecodeConfig returns the color model and dimensions of a PNG image without decoding the entire image.
Encode writes the Image m to w in PNG format. Any Image may be encoded, but images that are not image.NRGBA might be encoded lossily.
Package-Level Constants (total 4)