imageutil

package
v0.72.7 Latest Latest
Warning

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

 Go to latest Published: Jan 31, 2026 License: MIT Imports: 24 Imported by: 12

Documentation

Index

Constants

View Source 
const (
	AlignTop    = "top"
	AlignCenter = "center"
	AlignBottom = "bottom"
	AlignLeft   = "left"
	AlignRight  = "right"
)
View Source 
const (
	AlgNearestNeighbor = "nearestneighbor"
	AlgApproxBiLinear  = "approxbilinear"
	AlgBiLinear        = "bilinear"
	AlgCatmullRom      = "catmullrom"
)
View Source 
const (
	LocUpper      = "upper"
	LocMiddle     = "middle"
	LocLower      = "lower"
	LocLeft       = "left"
	LocCenter     = "center"
	LocRight      = "right"
	LocUpperLeft  = "upperleft"
	LocUpperRight = "upperright"
	LocLowerLeft  = "lowerleft"
	LocLowerRight = "lowerright"
)
View Source 
const (
	FileExtensionWebp = ".webp"

	FormatNameJPG  = "jpeg"
	FormatNamePNG  = "png"
	FormatNameWEBP = "webp"
)
View Source 
const (
	JPEGExt            = ".jpeg"
	JPEGExtJPG         = ".jpg"
	JPEGQualityDefault = jpeg.DefaultQuality // 75
	JPEGQualityMax     = 100
	JPEGQualityMin     = 1
	JPEGMarkerPrefix   = 0xff
	JPEGMarkerExif     = 0xe1
	JPEGMarkerSOI      = 0xd8
)

Variables

View Source 
var (
	ErrImageNotSet  = errors.New("image not set")
	ErrWriterNotSet = errors.New("writer not set")
)
View Source 
var (
	ErrSrcDirNotDefined = errors.New("source directory not defined")
	ErrOutDirNotDefined = errors.New("output directory not defined")
	ErrSrcDirNotDir     = errors.New("source directory is not a directory")
	ErrOutDirNotDir     = errors.New("output directory is not a directory")
)
View Source 
var JPEGEncodeOptionsQualityMax = &JPEGEncodeOptions{
	Options: &jpeg.Options{
		Quality: JPEGQualityMax}}
View Source 
var RxFileExtensionJPG = regexp.MustCompile(`(?i)^.*\.*jpe?g$`)

Functions

func AddBackgroundColor 

func AddBackgroundColor(img image.Image, clr color.Color) draw.Image

AddBackgroundColor adds a background of `color.Color` to an image. It is is useful when the image has a transparent background. Use `colornames` for more colors, e.g. `colornames.Blue`. This returns a `draw.Image` so it can be used as an input to `draw.Draw()`.

func AddBackgroundWhite 

func AddBackgroundWhite(img image.Image) image.Image

AddBackgroundWhite adds a white background which is usable when the image has a transparent background.

func AddBorder added in v0.35.7 

func AddBorder(img draw.Image, clr color.Color, width int) draw.Image

AddBorder adds a border to a `draw.Image`. If you have an `image.Image`, first convert it with `ImageToRGBA(img)`.

func AddBorderAverageColor added in v0.49.0 

func AddBorderAverageColor(img image.Image, width int) image.Image

func Aspect 

func Aspect(width, height int) float64

func Bleach added in v0.70.9 

func Bleach(img image.Image) image.Image

Bleach modifies near-white values to true-white.

func BuildGIFAnimationSimple added in v0.70.12 

func BuildGIFAnimationSimple(src *gif.GIF, delay int, imgs []image.Image, f ToPalettedFunc) *gif.GIF

BuildGifAnimationSimple assembles a set of images in an animated GIF file. Set `delay` to `0`.

func BuildGIFAnimationSimpleRead added in v0.70.12 

func BuildGIFAnimationSimpleRead(src *gif.GIF, delay int, names []string, f ToPalettedFunc, consistentSize bool) (*gif.GIF, error)

func ColsFilteredColor added in v0.33.3 

func ColsFilteredColor(img image.Image, c ...color.Color) []int

func Crop added in v0.35.0 

func Crop(src image.Image, retain image.Rectangle) image.Image

Crop takes an image and crops it to the specified rectangle.

func CropPadding added in v0.64.6 

func CropPadding(src image.Image, isPadding padding.IsPaddingFunc, retainPaddingWidth uint32) image.Image

func CropX added in v0.35.2 

func CropX(src image.Image, width int, align string) image.Image

CropX crops an image by its width horizontally.

func CropY added in v0.35.2 

func CropY(src image.Image, height int, align string) image.Image

CropY crops an image by its height vertically.

func DecodeBytes added in v0.51.0 

func DecodeBytes(data []byte) (image.Image, string, error)

DecodeBytes wraps Decode which 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.

func DecodeConfigFile added in v0.64.0 

func DecodeConfigFile(filename string) (image.Config, string, error)

func DecodeWebP added in v0.64.0 

func DecodeWebP(r io.Reader) (image.Image, string, error)

func EncodeJPEGWithExif added in v0.69.2 

func EncodeJPEGWithExif(w io.Writer, img image.Image, opts *jpeg.Options, exif []byte) error

EncodeJPEGWithExif encodes a JPEG image, inserts Exif data after the SOI marker, and writes to w.

func GammaCorrect added in v0.70.9 

func GammaCorrect(src image.Image, gamma float64) *image.RGBA

func ImageAspect 

func ImageAspect(img image.Image) float64

func ImageToPaletted added in v0.36.0 

func ImageToPaletted(src image.Image, p color.Palette) *image.Paletted

ImageToPaletted is used for GIF conversion.

func ImageToPalettedPlan9 added in v0.36.0 

func ImageToPalettedPlan9(src image.Image) *image.Paletted

ImageToPalettedPlan9 converts an image to `*image.Paletted`. See the go implementation here: https://github.com/golang/go/blob/master/src/image/gif/writer.go

func ImageToPalettedWebSafe added in v0.36.5 

func ImageToPalettedWebSafe(src image.Image) *image.Paletted

ImageToPalettedWebSafe uses the 216 color palette created by Netscape. This is only necessary for legacy/old applications. See more here: https://en.wikipedia.org/wiki/Web_colors#Web-safe_colors

func ImageToRGBA 

func ImageToRGBA(src image.Image) *image.RGBA

func IsImageExt 

func IsImageExt(imagePath string) bool

func IsNilOrEmpty 

func IsNilOrEmpty(img image.Image) bool

func JPEGMarker added in v0.49.0 

func JPEGMarker(b byte) []byte

func MergeXRGBA added in v0.36.5 

func MergeXRGBA(imgs []image.Image) image.Image

MergeXRGBA returns an image that is composed of non-overlapping imagers in ImageMetaSet. The code here is adapted from https://stackoverflow.com/a/35965499/1908967

func MergeXSameY 

func MergeXSameY(images []image.Image, larger bool) image.Image

func MergeXSameYRead 

func MergeXSameYRead(locations []string, larger bool) (image.Image, error)

func MergeYSameX 

func MergeYSameX(images []image.Image, larger bool) image.Image

func MergeYSameXRead 

func MergeYSameXRead(locations []string, larger bool) (image.Image, error)

func NewRGBAColor 

func NewRGBAColor(rect image.Rectangle, clr color.RGBA) *image.RGBA

func NewRGBATransparent 

func NewRGBATransparent(rect image.Rectangle) *image.RGBA

func NewRGBAWhite 

func NewRGBAWhite(rect image.Rectangle) *image.RGBA

func Overlay added in v0.35.1 

func Overlay(src, overlay image.Image, offset image.Point) image.Image

func OverlayMore added in v0.35.6 

func OverlayMore(src, overlay image.Image, overlayLocation string, padX, padY int) image.Image

func OverlayOffset added in v0.35.7 

func OverlayOffset(src, overlay image.Rectangle, overlayLocation string, padX, padY int) image.Point

func PaintBorder added in v0.35.7 

func PaintBorder(img draw.Image, clr color.Color, width int)

PaintBorder colorizes a border of size `width` in the existing canvas, overwriting any colors in that space.

func PaintColor added in v0.35.7 

func PaintColor(img draw.Image, clr color.Color, area image.Rectangle)

func ParseScaler 

func ParseScaler(rawInterpolation string) (draw.Scaler, error)

func ReadDirJPEGFiles added in v0.49.0 

func ReadDirJPEGFiles(dir string, rx *regexp.Regexp) (osutil.DirEntries, error)

func ReadImage added in v0.33.3 

func ReadImage(location string) (image.Image, string, error)

func ReadImageFile 

func ReadImageFile(filename string) (image.Image, string, error)

func ReadImageHTTP added in v0.37.1 

func ReadImageHTTP(imageURL string) (image.Image, string, error)

func ReadImages 

func ReadImages(locations []string) ([]image.Image, error)

func RectangleBorderXMax 

func RectangleBorderXMax(rect image.Rectangle, pixels int) image.Rectangle

func RectangleBorderXMin 

func RectangleBorderXMin(rect image.Rectangle, pixels int) image.Rectangle

func RectangleBorderYMax 

func RectangleBorderYMax(rect image.Rectangle, pixels int) image.Rectangle

func RectangleBorderYMin 

func RectangleBorderYMin(rect image.Rectangle, pixels int) image.Rectangle

func RectanglePixelCount added in v0.35.1 

func RectanglePixelCount(r image.Rectangle) int

func Resize 

func Resize(width, height int, src image.Image, scale draw.Scaler) image.Image

Resize scales an image to the provided size units. Use a 0 to scale the aspect ratio. See gitub.com/nfnt/resize for Lanczos3, etc. https://github.com/nfnt/resize .

func ResizeMax 

func ResizeMax(maxWidth, maxHeight int, src image.Image, scale draw.Scaler) image.Image

ResizeMax resizes an image to maximum dimensions. To resize to a maximum of 800 pixels width, the following can be used: `ResizeMax(800, 0, img, nil)`.

func ResizeMaxDimension 

func ResizeMaxDimension(maxDimension int, src image.Image, scale draw.Scaler) image.Image

ResizeMaxDimension resizes an image so that the max dimension matches what is supplied. If `maxDimension` is `0` or less a zero value `image.Image` is returned.

func ResizeMin 

func ResizeMin(minWidth, minHeight int, src image.Image, scale draw.Scaler) image.Image

ResizeMin resizes an image to minimum dimensions. To resize to a minimum of 800 pixels width, the following can be used: `ResizeMin(800, 0, img, nil)`.

func ResizePathJPEG added in v0.51.0 

func ResizePathJPEG(src, out string, x, y int, o *JPEGEncodeOptions) error

func ResizePathJPEGDir added in v0.51.0 

func ResizePathJPEGDir(src, out string, x, y int, o *JPEGEncodeOptions) error

func ResizePathJPEGFile added in v0.51.0 

func ResizePathJPEGFile(src, out string, x, y int, o *JPEGEncodeOptions) error

func ResizeSameX 

func ResizeSameX(images []image.Image, larger bool) []image.Image

func ResizeSameY 

func ResizeSameY(images []image.Image, larger bool) []image.Image

func RowsFilteredColor added in v0.33.2 

func RowsFilteredColor(img image.Image, c color.Color, cmore ...color.Color) []int

func Scale 

func Scale(src image.Image, rect image.Rectangle, scale draw.Scaler) image.Image

Scale will resize the image to the provided rectangle using the provided interpolation function.

func ScalerBest 

func ScalerBest() draw.Scaler

func ScalerDefault 

func ScalerDefault() draw.Scaler

ScalerDefault returns a general best results interpolation algorithm. See more here https://blog.codinghorror.com/better-image-resizing/ , https://support.esri.com/en/technical-article/000005606 , https://stackoverflow.com/questions/384991/what-is-the-best-image-downscaling-algorithm-quality-wise/6171860 .

func SliceXY 

func SliceXY(images []image.Image, maxIdx int) (minX, maxX, minY, maxY, sumX, sumY int)

func WriteGIFFile added in v0.51.0 

func WriteGIFFile(filename string, img *gif.GIF, perm os.FileMode) (err error)

WriteGIFFile writes a `*gif.GIF` to a filename.

Types

type Image added in v0.51.0 

type Image struct {
	image.Image
}

func (Image) GIF added in v0.70.8 

func (im Image) GIF() (*gif.GIF, error)

func (Image) GIFBytes added in v0.70.8 

func (im Image) GIFBytes() ([]byte, error)

func (Image) JPEGBytes added in v0.70.8 

func (im Image) JPEGBytes(opt *JPEGEncodeOptions) ([]byte, error)

func (Image) PNGBytes added in v0.70.8 

func (im Image) PNGBytes() ([]byte, error)

func (Image) Paletted added in v0.70.8 

func (im Image) Paletted() (*image.Paletted, error)

func (Image) SplitHorz added in v0.70.7 

func (im Image) SplitHorz(sqLarger bool, bgcolor color.Color) (imgLeft, imgRight image.Image, err error)

func (Image) SquareLarger added in v0.64.6 

func (im Image) SquareLarger(bgcolor color.Color) image.Image

SquareLarger returns a square image that is cropped to where the height and weight are equal to the larger of the source image. Additional padding is added, if necessary.

func (Image) SquareSmaller added in v0.64.6 

func (im Image) SquareSmaller() image.Image

SquareSmaller returns a square image that is cropped to where the height and weight are equal to the smaller of the source image. Source image pixes may be cropped and no additional pixels are added.

func (Image) WriteGIFFile added in v0.70.8 

func (im Image) WriteGIFFile(filename string) (err error)

func (Image) WriteJPEG added in v0.51.0 

func (im Image) WriteJPEG(w io.Writer, opt *JPEGEncodeOptions) error

func (Image) WriteJPEGFile added in v0.51.0 

func (im Image) WriteJPEGFile(filename string, opt *JPEGEncodeOptions) error

func (Image) WriteJPEGFileSimple added in v0.63.11 

func (im Image) WriteJPEGFileSimple(filename string, quality int) error

func (Image) WriteJPEGResponseWriter added in v0.51.0 

func (im Image) WriteJPEGResponseWriter(w http.ResponseWriter, addContentTypeHeader bool, opt *JPEGEncodeOptions) error

func (Image) WritePNG added in v0.51.0 

func (im Image) WritePNG(w io.Writer) error

func (Image) WritePNGFile added in v0.51.0 

func (im Image) WritePNGFile(filename string) error

func (Image) WritePNGResponseWriter added in v0.51.0 

func (im Image) WritePNGResponseWriter(w http.ResponseWriter, addContentTypeHeader bool) error

type ImageMeta 

type ImageMeta struct {
	File       *os.File
	FormatName string
	Image      image.Image
}

func NewImageMeta added in v0.35.0 

func NewImageMeta(img image.Image) ImageMeta

func (*ImageMeta) ColorAverage added in v0.33.2 

func (meta *ImageMeta) ColorAverage() color.Color

func (*ImageMeta) ColorsHistogram added in v0.64.6 

func (meta *ImageMeta) ColorsHistogram() map[string]uint

func (*ImageMeta) ColorsMatrix added in v0.64.6 

func (meta *ImageMeta) ColorsMatrix() [][]color.Color

ColorsMatrix returns colors for an image covering the pixels described in `image.Rectangle`: https://pkg.go.dev/image#Rectangle

type ImageMetaSet 

type ImageMetaSet struct {
	ImageMetas []ImageMeta
}

func NewImageSetFiles 

func NewImageSetFiles(filenames []string) (ImageMetaSet, error)

func (*ImageMetaSet) CloseFilesAll 

func (ims *ImageMetaSet) CloseFilesAll() error

func (*ImageMetaSet) Images added in v0.37.8 

func (ims *ImageMetaSet) Images() []image.Image

func (*ImageMetaSet) MaxX 

func (ims *ImageMetaSet) MaxX() int

func (*ImageMetaSet) MaxY 

func (ims *ImageMetaSet) MaxY() int

func (*ImageMetaSet) Stats 

func (ims *ImageMetaSet) Stats() ImagesStats

func (*ImageMetaSet) SumX 

func (ims *ImageMetaSet) SumX(maxIndexInclusive int) int

func (*ImageMetaSet) SumY 

func (ims *ImageMetaSet) SumY(maxIndexInclusive int) int

type ImageMetadata added in v0.64.5 

type ImageMetadata struct {
	Width  int
	Height int
}

func NewImageMetadata added in v0.64.5 

func NewImageMetadata(img image.Image) ImageMetadata

type Images added in v0.36.5 

type Images []image.Image

func (Images) ConsistentSize added in v0.36.5 

func (imgs Images) ConsistentSize(scale draw.Scaler, yAlign string)

ConsistentSize resizes and crops the images so that they have all the same size. It prioritize resizing images to max Dx and then cropping Dy so they are consistent.

func (Images) Dimensions added in v0.37.8 

func (imgs Images) Dimensions() []image.Point

func (Images) DxMax added in v0.36.5 

func (imgs Images) DxMax() int

func (Images) DxMin added in v0.36.5 

func (imgs Images) DxMin() int

func (Images) DxSum added in v0.36.5 

func (imgs Images) DxSum(maxIndexInclusive int) int

DxSum returns the sum of widths up to and including `maxIndexInclusive`. Use a negative value for `maxIndexInclusive` to include all elements.

func (Images) Dxs added in v0.36.5 

func (imgs Images) Dxs() []int

func (Images) DyMax added in v0.36.5 

func (imgs Images) DyMax() int

func (Images) DyMin added in v0.36.5 

func (imgs Images) DyMin() int

func (Images) DySum added in v0.36.5 

func (imgs Images) DySum(maxIndexInclusive int) int

DySum returns the sum of heights up to and including `maxIndexInclusive`. Use a negative value for `maxIndexInclusive` to include all elements.

func (Images) Dys added in v0.36.5 

func (imgs Images) Dys() []int

func (Images) Stats added in v0.36.5 

func (imgs Images) Stats() ImagesStats

type ImagesStats added in v0.36.5 

type ImagesStats struct {
	Dxs   []int
	DxMax int
	DxMin int
	DxSum int
	Dys   []int
	DyMax int
	DyMin int
	DySum int
}

type JPEGEncodeOptions added in v0.49.0 

type JPEGEncodeOptions struct {
	Options            *jpeg.Options
	Exif               []byte
	ReadFilenameRegexp *regexp.Regexp
	WriteExtension     string
}

func (JPEGEncodeOptions) ReadFilenameRegexpOrDefault added in v0.49.0 

func (opts JPEGEncodeOptions) ReadFilenameRegexpOrDefault() *regexp.Regexp

func (JPEGEncodeOptions) WriteExtensionOrDefault added in v0.49.0 

func (opts JPEGEncodeOptions) WriteExtensionOrDefault() string

type Matrix 

type Matrix [][]image.Image

func MatrixRead 

func MatrixRead(imglocations [][]string) (Matrix, error)

func (Matrix) AddBackgroundColor 

func (matrix Matrix) AddBackgroundColor(clr color.Color)

AddBackgroundColor adds a background of `color.Color` to the images. It is is useful when the image has a transparent background. Use `colornames` for more colors, e.g. `colornames.Blue`.

func (Matrix) AddBackgroundColorHex 

func (matrix Matrix) AddBackgroundColorHex(hexcolor string) error

func (Matrix) Dimensions added in v0.37.8 

func (matrix Matrix) Dimensions() [][]image.Point

func (Matrix) DxSumMax added in v0.37.8 

func (matrix Matrix) DxSumMax() int

func (Matrix) DxSumMin added in v0.37.8 

func (matrix Matrix) DxSumMin() int

func (Matrix) Merge 

func (matrix Matrix) Merge(largerX, largerY bool) image.Image

Merge combines a set of images resizing each row element's height for consistent rows, an each row's width for consistent widths.

type SOIFilterWriter added in v0.69.2 

type SOIFilterWriter struct {
	// contains filtered or unexported fields
}

SOIFilterWriter is a writer that filters out the SOI marker (0xFF 0xD8) from JPEG data.

func NewSOIFilterWriter added in v0.69.2 

func NewSOIFilterWriter(w io.Writer) *SOIFilterWriter

func (*SOIFilterWriter) Close added in v0.69.2 

func (s *SOIFilterWriter) Close() error

Close implements io.Closer

func (*SOIFilterWriter) Write added in v0.69.2 

func (s *SOIFilterWriter) Write(p []byte) (n int, err error)

type ToPalettedFunc added in v0.36.5 

type ToPalettedFunc func(src image.Image) *image.Paletted

Source Files

View all Source files

Directories

Path Synopsis
cmd
resize_jpeg command
webp2jpeg command

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.