Run Format

Package jpeg

import "image/jpeg"

Overview ▾

Package jpeg implements a JPEG image decoder and encoder.

JPEG is defined in ITU-T T.81: http://www.w3.org/Graphics/JPEG/itu-t81.pdf.


const DefaultQuality = 75

DefaultQuality is the default quality encoding parameter.

func Decode

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

Decode reads a JPEG image from r and returns it as an image.Image.

func DecodeConfig

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

DecodeConfig returns the color model and dimensions of a JPEG image without decoding the entire image.

func Encode

func Encode(w io.Writer, m image.Image, o *Options) error

Encode writes the Image m to w in JPEG 4:2:0 baseline format with the given options. Default parameters are used if a nil *Options is passed.

type FormatError

type FormatError string

A FormatError reports that the input is not a valid JPEG.

func (FormatError) Error

func (e FormatError) Error() string

type Options

type Options struct {
        Quality int

Options are the encoding parameters. Quality ranges from 1 to 100 inclusive, higher is better.

type Reader

type Reader interface {
        ReadByte() (c byte, err error)

If the passed in io.Reader does not also have ReadByte, then Decode will introduce its own buffering.

type UnsupportedError

type UnsupportedError string

An UnsupportedError reports that the input uses a valid but unimplemented JPEG feature.

func (UnsupportedError) Error

func (e UnsupportedError) Error() string