image

package
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 Go to latest Published: Jan 10, 2024 License: Apache-2.0 Imports: 16 Imported by: 1

Documentation

Overview

Package image contains functions that mostly operate on image.Gray.

Logical Operations 

And
Or
Xor
Not
Sub
Equal
Copy

Morphological Operations 

Dilate
Erode
Open
Close
TopHat
BotHat
HitOrMiss
Thin
Skeleton
LJSkeleton
LJReconstitute

Remap Operations 

ColorConvert
RemapGray
RemapRGBA

Channel Operations 

ExtractChannel
ReplaceChannel
SwitchChannels
CombineChannels

Various metrics 

Histogram
CDF
Variance

Image types: 

Patch - replicates a patch of colors across the plane like Uniform does for a single color
Tile - replicates an image across the plane

Index

Constants

This section is empty.

Variables

View Source 
var (

	// Z0 the point itself
	Z0 = [][]bool{
		{true},
	}

	// Z4 3x3 Von Neumann 4-way
	Z4 = [][]bool{
		{false, true, false},
		{true, true, true},
		{false, true, false},
	}

	// X4 3x3 X
	X4 = [][]bool{
		{true, false, true},
		{false, true, false},
		{true, false, true},
	}

	// Z8 3x3 Moore 8-way
	Z8 = [][]bool{
		{true, true, true},
		{true, true, true},
		{true, true, true},
	}

	// Cross5x5 5x5 cross
	Cross5x5 = [][]bool{
		{false, false, true, false, false},
		{false, false, true, false, false},
		{true, true, true, true, true},
		{false, false, true, false, false},
		{false, false, true, false, false},
	}

	// X5 5x5 X
	X5 = [][]bool{
		{true, false, false, false, true},
		{false, true, false, true, false},
		{false, false, true, false, false},
		{false, true, false, true, false},
		{true, false, false, false, true},
	}

	// Star5x5 5x5 star
	Star5x5 = [][]bool{
		{true, false, true, false, true},
		{false, true, true, true, false},
		{true, true, true, true, true},
		{false, true, true, true, false},
		{true, false, true, false, true},
	}

	// Diamond5x5 5x5 diamond
	Diamond5x5 = [][]bool{
		{false, false, true, false, false},
		{false, true, true, true, false},
		{true, true, true, true, true},
		{false, true, true, true, false},
		{false, false, true, false, false},
	}

	// Ball5x5 5x5 ball
	Ball5x5 = [][]bool{
		{false, true, true, true, false},
		{true, true, true, true, true},
		{true, true, true, true, true},
		{true, true, true, true, true},
		{false, true, true, true, false},
	}

	// All5x5 5x5 block
	All5x5 = [][]bool{
		{true, true, true, true, true},
		{true, true, true, true, true},
		{true, true, true, true, true},
		{true, true, true, true, true},
		{true, true, true, true, true},
	}

	C11 = [][]bool{
		{false, false, false},
		{false, true, false},
		{true, true, true},
	}
	D11 = [][]bool{
		{true, true, true},
		{false, false, false},
		{false, false, false},
	}

	C12 = [][]bool{
		{true, false, false},
		{true, true, false},
		{true, false, false},
	}
	D12 = [][]bool{
		{false, false, true},
		{false, false, true},
		{false, false, true},
	}

	C13 = [][]bool{
		{true, true, true},
		{false, true, false},
		{false, false, false},
	}
	D13 = [][]bool{
		{false, false, false},
		{false, false, false},
		{true, true, true},
	}

	C14 = [][]bool{
		{false, false, true},
		{false, true, true},
		{false, false, true},
	}
	D14 = [][]bool{
		{true, false, false},
		{true, false, false},
		{true, false, false},
	}

	C21 = [][]bool{
		{false, false, false},
		{true, true, false},
		{true, true, false},
	}
	D21 = [][]bool{
		{false, true, true},
		{false, false, true},
		{false, false, false},
	}

	C22 = [][]bool{
		{true, true, false},
		{true, true, false},
		{false, false, false},
	}
	D22 = [][]bool{
		{false, false, false},
		{false, false, true},
		{false, true, true},
	}

	C23 = [][]bool{
		{false, true, true},
		{false, true, true},
		{false, false, false},
	}
	D23 = [][]bool{
		{false, false, false},
		{true, false, false},
		{true, true, false},
	}

	C24 = [][]bool{
		{false, false, false},
		{false, true, true},
		{false, true, true},
	}
	D24 = [][]bool{
		{true, true, false},
		{true, false, false},
		{false, false, false},
	}
)

Functions

func AlphaAnd 

func AlphaAnd(img1, img2 *image.Alpha, offs image.Point) *image.Alpha

AlphaAnd returns img1 & img2 (intersection). For a pair of pixels, p1 & p2 returns min(p1, p2).

func AlphaCopy 

func AlphaCopy(img *image.Alpha) *image.Alpha

AlphaCopy returns a deep copy of img.

func AlphaEqual 

func AlphaEqual(img1, img2 *image.Alpha, offs image.Point) bool

AlphaEqual returns true if two images are the same.

func AlphaNot 

func AlphaNot(img *image.Alpha) *image.Alpha

AlphaNot returns 1 - img.

func AlphaOr 

func AlphaOr(img1, img2 *image.Alpha, offs image.Point) *image.Alpha

AlphaOr returns img1 | img2 (union). For a pair of pixels, p1 | p2 returns max(p1, p2).

func AlphaSub 

func AlphaSub(img1, img2 *image.Alpha, offs image.Point) *image.Alpha

AlphaSub returns img1 - img2 (img1 minus the intersection of img1 and img2). For a pair of pixels, p1 - p2 returns min(p1, 1-p2).

func AlphaToGray 

func AlphaToGray(a *image.Alpha) *image.Gray

AlphaToGray does a shallow copy (vs going through the ColorModel).

func AlphaXor 

func AlphaXor(img1, img2 *image.Alpha, offs image.Point) *image.Alpha

AlphaXor returns img1 ^ img2 (union - intersection). For a pair of pixels, p1 ^ p2 returns min(max(p1, p2), 1-min(p1, p2)).

func And 

func And(img1, img2 image.Image, offs image.Point) *image.Gray

And returns the result of ANDing img1 with img2, offset by offs (intersection). The images are converted to image.Gray if not already so. For a pair of pixels, p1 & p2 returns min(p1, p2).

func AvgOp 

func AvgOp(values [][]uint8, support [][]bool) uint8

AvgOp finds the average value (rounded down) of all the values that have the support set.

func BotHat 

func BotHat(img image.Image, support [][]bool) *image.Gray

BotHat is the subtraction of the original from a close.

func CDF 

func CDF(hist []int) []float64

CDF computes the normalized cummulative distribution function of the histogram.

func Close 

func Close(img image.Image, support [][]bool) *image.Gray

Close applies an erosion to a prior dilation.

func ColorConvert 

func ColorConvert(img *image.NRGBA, xfm *Aff5) *image.NRGBA

ColorConvert runs NRGBA through the supplied affine transform.

func CombineChannels 

func CombineChannels(chR, chG, chB, chA *image.Gray, scale bool) *image.RGBA

CombineChannels combines mono-channel images into a single image. The R, G, B channels will be scaled by alpha if scale is true.

func Copy 

func Copy(img image.Image) *image.Gray

Copy creates a grayscale copy of img

func CopyAlpha 

func CopyAlpha(in *image.Alpha) *image.Alpha

CopyAlpha clones an Alpha image.

func CopyGray 

func CopyGray(in *image.Gray) *image.Gray

CopyGray clones a Gray image.

func CopyGray16 

func CopyGray16(in *image.Gray16) *image.Gray16

CopyGray16 clones a Gray16 image.

func CopyRGBA 

func CopyRGBA(in *image.RGBA) *image.RGBA

CopyRGBA clones an RGBA image.

func CreateLutFromValues 

func CreateLutFromValues(values []float64) []uint8

CreateLutFromValues maps a series of values in [0,1] to [0,255] Note - no checking on values range

func Dilate 

func Dilate(img image.Image, support [][]bool) *image.Gray

Dilate replaces each pixel with the max of the pixels in its support.

func Displace 

func Displace(img draw.Image, r image.Rectangle, xchan image.Image, xoffs image.Point, xscale float64,
	ychan image.Image, yoffs image.Point, yscale float64)

Displace displaces the image within the rectangle by the amounts referenced in the other two images (one each for X and Y) scaled. If the displaced location exceeds the bounds of the rectangle, it is wrapped. Black maps to scale * -0.5 and white to scale * 0.5.

func Equal 

func Equal(img1, img2 image.Image, offs image.Point) bool

Equal returns true if img1 within img2 at offset offs, matches.

func Erode 

func Erode(img image.Image, support [][]bool) *image.Gray

Erode replaces each pixel with the min of the pixels in its support.

func ExtractChannel 

func ExtractChannel(img *image.RGBA, ch int) *image.Gray

ExtractChannel returns an image with just the selected channel. The returned image is scaled by 1/alpha, if not the alpha channel.

func GrayToAlpha 

func GrayToAlpha(a *image.Gray) *image.Alpha

GrayToAlpha does a shallow copy (vs going through the ColorModel).

func GrayToSupport 

func GrayToSupport(img *image.Gray) [][]bool

GrayToSupport converts a gray scale image to a support.

func Histogram 

func Histogram(img *image.Gray) ([]int, int, int)

Histogram computes the histogram of the image and the first and last non-zero entry positions

func HitOrMiss 

func HitOrMiss(img image.Image, support1, support2 [][]bool) *image.Gray

HitOrMiss keeps support1 and not support2 in the image. It requires that the intersection of the two supports be empty.

func LJReconstitute 

func LJReconstitute(skels []*image.Gray, b [][]bool) *image.Gray

LJReconstitute turns a set of skeletons back into the opened version of the original image using the support.

func LJSkeleton 

func LJSkeleton(img image.Image, b [][]bool, n int) []*image.Gray

LJSkeleton calculates the skeletons of the image using Lanuejoul's formula over n iterations with support b. Each skeleton is formed from the tophat of the image eroded by the support b dilated by itself n times. The last skeleton is the union of the previous skeletons. See https://en.wikipedia.org/wiki/Morphological_skeleton

func MaxOp 

func MaxOp(values [][]uint8, support [][]bool) uint8

MaxOp finds the highest value in values that has the support set.

func MedOp 

func MedOp(values [][]uint8, support [][]bool) uint8

MedOp finds the midway value of all the values, sorted, that have the support set.

func MinOp 

func MinOp(values [][]uint8, support [][]bool) uint8

MinOp finds the lowest value in values that has the support set.

func Morphological 

func Morphological(img image.Image, op func([][]uint8, [][]bool) uint8, support [][]bool, def uint8) *image.Gray

Morphological runs op over the image img using support and supplying def when a location falls outside of the image boundary. The support dimensions must be odd (not checked for).

func NLExpansionLut 

func NLExpansionLut(n, start, end int, f util.NonLinear) []uint8

NLExpansionLut generates a lut [start,end), normalized and mapped through f. For example NLExpansionLut(256, 0, 256, &NLSin{}) will generate a Sin ramp.

func NewAlpha 

func NewAlpha(w, h int, col color.Color) *image.Alpha

NewAlpha is a wrapper for image.Alpha which returns a new image of the desired size filled with color.

func NewAlphaVal 

func NewAlphaVal(w, h int, a uint8) *image.Alpha

NewAlphaVal is a wrapper for image.Alpha which returns a new image of the desired size filled with color.

func NewGray 

func NewGray(w, h int, col color.Color) *image.Gray

NewGray is a wrapper for image.Gray which returns a new image of the desired size filled with color.

func NewGray16 

func NewGray16(w, h int, col color.Color) *image.Gray16

NewGray16 is a wrapper for image.Gray16 which returns a new image of the desired size filled with color.

func NewGray16Val 

func NewGray16Val(w, h int, g uint16) *image.Gray16

NewGray16Val is a wrapper for image.Gray which returns a new image of the desired size filled with color.

func NewGrayVal 

func NewGrayVal(w, h int, g uint8) *image.Gray

NewGrayVal is a wrapper for image.Gray which returns a new image of the desired size filled with color.

func NewRGBA 

func NewRGBA(w, h int, col color.Color) *image.RGBA

NewRGBA is a wrapper for image.RGBA which returns a new image of the desired size filled with color.

func NewRGBAVal 

func NewRGBAVal(w, h int, r, g, b, a uint8) *image.RGBA

NewRGBAVal is a wrapper for image.RGBA which returns a new image of the desired size filled with color.

func Not 

func Not(img image.Image) *image.Gray

Not returns 1 - img.

func Open 

func Open(img image.Image, support [][]bool) *image.Gray

Open applies a dilation to a prior erosion.

func Or 

func Or(img1, img2 image.Image, offs image.Point) *image.Gray

Or returns the result of ORing img1 with img2, offset by offs (union). The images are converted to image.Gray if not already so. For a pair of pixels, p1 & p2 returns max(p1, p2).

func PremulLut 

func PremulLut(lut []uint8) [][]uint8

PremulLut creates a slice of luts from lut for every possible value of alpha

func ReadImage 

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

ReadImage is a utility function to read an image from a file.

func RemapGray 

func RemapGray(img *image.Gray, lut []uint8) *image.Gray

RemapGray remaps a color map with a look up table. The lookup table must be 256 long.

func RemapGray2RGBA 

func RemapGray2RGBA(img image.Image, lut []color.Color) *image.RGBA

RemapGray2RGBA remaps a grayscale image to an RGBA one using a look up table. The lookup table must be 256 long.

func RemapRGB 

func RemapRGB(img *image.RGBA, lutR, lutG, lutB []uint8) *image.RGBA

RemapRGB remaps all the color maps with R, G, B look up tables. The lookup tables must all be 256 long. The maps are applied after alpha pre-multiplication.

func RemapRGBSingle 

func RemapRGBSingle(img *image.RGBA, lut []uint8) *image.RGBA

RemapRGBSingle remaps all the color maps with a single look up table. The lookup table must be 256 long. The maps are applied after alpha pre-multiplication.

func ReplaceChannel 

func ReplaceChannel(img *image.RGBA, ch int, rep *image.Gray) *image.RGBA

ReplaceChannel in an image with the one supplied. The supplied image is scaled by alpha, if one of R, G or B. If the alpha channel is replaced then RGB are first scaled by 1/alpha and then by alpha'

func SaveImage 

func SaveImage(img image.Image, name string) error

SaveImage is a utility function to save an image as a .png.

func Skeleton 

func Skeleton(img image.Image) *image.Gray

Skeleton repeatedly thins the image until it's no longer changing. This operation can take a while to converge.

func Sub 

func Sub(img1, img2 image.Image, offs image.Point) *image.Gray

Sub returns the result of subtracting img2 from img1, offset by offs. The images are converted to image.Gray if not already so. For a pair of pixels, p1 & p2 returns max(0, p1-p2).

func SupportToGray 

func SupportToGray(suppt [][]bool) *image.Gray

SupportToGray converts a support to a gray scale image.

func SwitchChannels 

func SwitchChannels(img *image.RGBA, ch1, ch2 int) *image.RGBA

SwitchChannels in an image (not alpha)

func Thin 

func Thin(img image.Image) *image.Gray

Thin thins the image by repeatedly subtracting HitOrMiss with the selected support pairs.

func ThinStep 

func ThinStep(img image.Image, support1, support2 [][]bool) *image.Gray

ThinStep thins the image by subtracting HitOrMiss with a support pair.

func TopHat 

func TopHat(img image.Image, support [][]bool) *image.Gray

TopHat is the subtraction of an open from the original.

func Variance 

func Variance(img1, img2 *image.Gray) (float64, int)

Variance provides a normalized metric on how different two images are. It's not a strict statistical variance but the sum of the differences over the image size and number of differences.

func Xor 

func Xor(img1, img2 image.Image, offs image.Point) *image.Gray

Xor returns of XORing img1 with img2, offset by offs (union - intersection). The images are converted to image.Gray if not already so. For a pair of pixels, p1 ^ p2 returns min(max(p1, p2), 1-min(p1, p2)).

Types

type Aff5 

type Aff5 [20]float64

Aff5 is a 5x5 affine transformation matrix in row major order, where the bottom row is implicitly [0 0 0 0 1].

m[5*r+c] is the element in the r'th row and c'th column.

func Grayscale 

func Grayscale(t float64) *Aff5

Grayscale returns a transform that will create a gray tinted image.

func HueRotate 

func HueRotate(th float64) *Aff5

HueRotate returns a transform that will rotate the hue selection by th radians.

func LuminanceToAlpha 

func LuminanceToAlpha() *Aff5

LuminanceToAlpha returns a transform that will write just the luminance to the alpha channel.

func NewAff5 

func NewAff5() *Aff5

NewAff5 creates the identity transform.

func Saturate 

func Saturate(s float64) *Aff5

Saturate returns a transform that will modify the saturation of an image by s (0, 1)

func Sepia 

func Sepia(t float64) *Aff5

Sepia returns a transform that will create a sepia tinted image.

func (*Aff5) Apply 

func (a *Aff5) Apply(pts ...[]float64) [][]float64

Apply applies the transform to the set of supplied points.

func (*Aff5) Identity 

func (a *Aff5) Identity() bool

Identity returns true if the transform is the identity.

func (*Aff5) Transform 

func (a *Aff5) Transform(tup []uint8) []uint8

Transform transforms an r, g, b, a tuple into r', g', b', a' according to the values in a.

type Bit 

type Bit struct {
	Bits   datastruct.Bits
	SetC   color.RGBA // color returned when bit is set
	ClearC color.RGBA // color returned when bit is clear
	Stride int
	Thresh uint32 // threshold above which a bit is set in the RGB conversion
	Rect   image.Rectangle
}

Bit image uses a bit array to store data. The default colors assigned to bit values are color.White for set and color.Black for clear. These can be modified.

func NewBit 

func NewBit(r image.Rectangle) *Bit

NewTile creates a new image with the supplied bounds.

func (*Bit) At 

func (b *Bit) At(x, y int) color.Color

At implements the At function in the Image interface.

func (*Bit) Bounds 

func (b *Bit) Bounds() image.Rectangle

Bounds implements the Bounds function in the Image interface.

func (*Bit) ColorModel 

func (b *Bit) ColorModel() color.Model

ColorModel implements the ColorModel function in the Image interface.

func (*Bit) Set 

func (b *Bit) Set(x, y int, c color.Color)

Set implements the Set function in the draw.Image interface.

type Colorizer 

type Colorizer struct {
	Img  image.Image
	Rect image.Rectangle
	Lut  []color.RGBA
	G16  bool
}

Colorizer uses the gray or red channel of an image to create an image tinted with a lerp'd gradient between two or more colors.

func NewColorizer 

func NewColorizer(img image.Image, c1, c2 color.Color, stops []int, colors []color.Color, post bool) *Colorizer

NewColorizer creates a new Colorizer and creates the internal lut. c1 and c2 are the colors at the start and end of the colorizer. The stops (in range [1,254] and colors values determine any intermediate points and can be nil. The post flag turns off the lerping between colors and yields a posterized image.

func (*Colorizer) At 

func (c *Colorizer) At(x, y int) color.Color

At implements the At function in the Image interface.

func (*Colorizer) Bounds 

func (c *Colorizer) Bounds() image.Rectangle

Bounds implements the Bounds function in the Image interface.

func (*Colorizer) ColorModel 

func (c *Colorizer) ColorModel() color.Model

ColorModel implements the ColorModel function in the Image interface.

type Patch 

type Patch struct {
	Colors [][]color.RGBA
	Width  int
	Height int
	OffsX  int
	OffsY  int
}

Patch is an infinite image covered with a patch of colors.

func NewPatch 

func NewPatch(colors [][]color.Color) (*Patch, error)

NewPatch creates a new image with the supplied patch.

func (*Patch) At 

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

At implements the At function in the Image interface.

func (*Patch) Bounds 

func (p *Patch) Bounds() image.Rectangle

Bounds implements the Bounds function in the Image interface.

func (*Patch) ColorModel 

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

ColorModel implements the ColorModel function in the Image interface.

type Tile 

type Tile struct {
	TileImg *image.RGBA
	Width   int
	Height  int
	OffsX   int
	OffsY   int
	StagX   int
	StagY   int
}

Tile is an infinite image covered with a tile.

func NewTile 

func NewTile(img image.Image) *Tile

NewTile creates a new image with the supplied image tile.

func (*Tile) At 

func (t *Tile) At(x, y int) color.Color

At implements the At function in the Image interface.

func (*Tile) Bounds 

func (t *Tile) Bounds() image.Rectangle

Bounds implements the Bounds function in the Image interface.

func (*Tile) ColorModel 

func (t *Tile) ColorModel() color.Model

ColorModel implements the ColorModel function in the Image interface.

Source Files

View all Source files

Directories

Path Synopsis
Package texture contains functions that populate images with texture.
 Package texture contains functions that populate images with texture.

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