func TestAdjustGamma(t *testing.T) {
src := image.NewGray(image.Rect(0, 0, 256, 1))
dst := image.NewGray(image.Rect(0, 0, 256, 1))
for i := 0; i <= 255; i++ {
src.Pix[i] = uint8(i)
}
ag := Gamma(2.0)
ag.Draw(dst, src, nil)
for i := 100; i <= 150; i++ {
if dst.Pix[i] <= src.Pix[i] {
t.Errorf("Gamma unexpected color")
}
}
ag = Gamma(0.5)
ag.Draw(dst, src, nil)
for i := 100; i <= 150; i++ {
if dst.Pix[i] >= src.Pix[i] {
t.Errorf("Gamma unexpected color")
}
}
ag = Gamma(1.0)
ag.Draw(dst, src, nil)
for i := 100; i <= 150; i++ {
if dst.Pix[i] != src.Pix[i] {
t.Errorf("Gamma unexpected color")
}
}
}
// DrawPicture .
func DrawPicture(src image.Image, width int, height int) *image.Gray {
rect := image.Rect(0, 0, width, height)
img := image.NewGray(rect)
rander := rander()
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
var c color.Gray
if IsBlack(src, x, y) {
if y > 1 && IsNotBlack(src, x, y-1) {
c = borderColor(rander)
} else {
c = insideColor(rander)
}
} else {
c = outsideColor(rander)
}
x1, y1 := transformCurve(x, y, width, height)
//c = color.Gray{c.Y + ScaledLuminanceAt(90, src, x, y)}
img.Set(x1, y1, c)
}
}
g := gift.New(
//gift.GaussianBlur(2),
)
img2 := image.NewGray(rect)
g.Draw(img2, img)
return img2
}
func MakeComputeMaker(src image.Image) *ComMaker {
b := src.Bounds()
sz := b.Size()
width := sz.X / 8
height := sz.Y / 8
smallB := image.Rect(0, 0, width, height)
cm := ComMaker{
width: sz.X / 8,
height: sz.Y / 8,
bound: smallB,
}
// Make Grey Img
gSrc := image.NewGray(b)
draw.Draw(gSrc, b, src, image.ZP, draw.Src)
// Make Smaller
gDst := image.NewGray(smallB)
// Prep Conversion
cfg, err := rez.PrepareConversion(gDst, gSrc)
if err != nil {
log.Println(err)
return nil
}
cm.rConv, err = rez.NewConverter(cfg, rez.NewBilinearFilter())
if err != nil {
log.Println(err)
return nil
}
return &cm
}
func TestEdgeOps(t *testing.T) {
src, err := loadImage("../../testdata/gopher-100x150.png")
if err != nil {
t.Fatal(err)
}
for _, ot := range opTests {
mag := image.NewGray(src.Bounds())
dir := image.NewGray(src.Bounds())
if err := ot.fn(mag, dir, src); err != nil {
t.Fatalf("%s: %v", ot.name, err)
}
magFile := fmt.Sprintf("../../testdata/%s-mag.png", ot.name)
cmp, err := loadImage(magFile)
if err != nil {
t.Fatalf("%s mag: %v", ot.name, err)
}
if err = imageWithinTolerance(mag, cmp, 0x101); err != nil {
t.Fatalf("%s mag: %v", ot.name, err)
}
dirFile := fmt.Sprintf("../../testdata/%s-dir.png", ot.name)
cmp, err = loadImage(dirFile)
if err != nil {
t.Fatalf("%s dir: %v", ot.name, err)
}
if err = imageWithinTolerance(dir, cmp, 0x101); err != nil {
t.Fatalf("%s dir: %v", ot.name, err)
}
}
}
func ToComputeImageManual(src image.Image) *image.Gray {
fullBound := src.Bounds()
m := image.NewGray(fullBound)
draw.Draw(m, fullBound, src, image.ZP, draw.Src)
// Smaller Image
smallBound := image.Rect(0, 0, fullBound.Dx()/4, fullBound.Dy()/4)
smallImg := image.NewGray(smallBound)
swid := smallBound.Dx()
wid := fullBound.Dx()
for o, o2, omax := 0, 0, len(smallImg.Pix); o < omax; o, o2 = o+1, o2+4 {
if (o % swid) == 0 {
o2 = (o / swid) * wid * 4
}
smallImg.Pix[o] = uint8((int(m.Pix[o2+0]) +
int(m.Pix[o2+3]) +
int(m.Pix[o2+2+wid]) +
int(m.Pix[o2+1+wid*2]) +
int(m.Pix[o2+0+wid*3]) +
int(m.Pix[o2+3+wid*3])) / 6)
}
return smallImg
}
func main() {
flag.Parse()
reader, err := os.Open(*in)
if err != nil {
log.Fatal(err)
}
defer reader.Close()
i, _, err := image.Decode(reader)
if err != nil {
log.Fatal(err)
}
b := i.Bounds()
m := image.NewGray(b) // monochrome
draw.Draw(m, b, i, b.Min, draw.Src)
o := image.NewGray(image.Rect(0, 0, 256, 256))
white := color.RGBA{0xff, 0xff, 0xff, 0xff}
black := color.RGBA{0x00, 0x00, 0x00, 0xff}
draw.Draw(o, o.Bounds(), &image.Uniform{white}, image.ZP, draw.Src)
delta := []int{-16, -1, 1, 16}
ud := []int{-6, 0, 0, 6}
lr := []int{0, -6, 6, 0}
for j := 0; j < 16; j++ {
for i := 0; i < 16; i++ {
cx := int(19 + 20.5333*float64(i))
cy := int(19 + 20.5333*float64(j))
s := []uint32{0, 0, 0, 0}
best := uint32(50000)
bestK := 0
for k := 0; k < 4; k++ {
for sx := -1; sx < 2; sx++ {
for sy := -1; sy < 2; sy++ {
r, g, b, _ := m.At(cx+lr[k]+sx, cy+ud[k]+sy).RGBA()
s[k] += (r + g + b) / 3
}
}
if k == 0 || s[k] < best {
best = s[k]
bestK = k
}
}
src := 16*j + i
dst := (src + delta[bestK] + 256) % 256
fmt.Printf("%v\n", dst)
o.Set(src, dst, black)
}
}
writer, err := os.Create(*out)
if err != nil {
log.Fatal(err)
}
png.Encode(writer, o)
writer.Close()
}
func TestRotate270(t *testing.T) {
img0 := image.NewGray(image.Rect(-1, -1, 3, 1))
img0.Pix = []uint8{
1, 2, 3, 4,
5, 6, 7, 8,
}
img1Exp := image.NewGray(image.Rect(0, 0, 2, 4))
img1Exp.Pix = []uint8{
5, 1,
6, 2,
7, 3,
8, 4,
}
f := Rotate270()
img1 := image.NewGray(f.Bounds(img0.Bounds()))
f.Draw(img1, img0, nil)
if img1.Bounds().Size() != img1Exp.Bounds().Size() {
t.Errorf("expected %v got %v", img1Exp.Bounds().Size(), img1.Bounds().Size())
}
if !comparePix(img1Exp.Pix, img1.Pix) {
t.Errorf("expected %v got %v", img1Exp.Pix, img1.Pix)
}
}
// Canny detects and returns edges from the given image.
// Each dst pixel is given one of three values:
// 0xff: an edge
// 0x80: possibly an edge
// 0x00: not an edge
func Canny(dst *image.Gray, src image.Image) error {
if dst == nil {
return errors.New("edge: dst is nil")
}
if src == nil {
return errors.New("edge: src is nil")
}
b := src.Bounds()
srcGray, ok := src.(*image.Gray)
if !ok {
srcGray = image.NewGray(b)
draw.Draw(srcGray, b, src, b.Min, draw.Src)
}
if err := graphics.Blur(srcGray, srcGray, nil); err != nil {
return err
}
mag, dir := image.NewGray(b), image.NewGray(b)
if err := Sobel(mag, dir, srcGray); err != nil {
return err
}
// Non-maximum supression.
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
d := dir.Pix[(y-b.Min.Y)*dir.Stride+(x-b.Min.X)*1]
var m0, m1 uint8
switch d {
case 0: // west and east
m0 = atOrZero(mag, x-1, y)
m1 = atOrZero(mag, x+1, y)
case 45: // north-east and south-west
m0 = atOrZero(mag, x+1, y-1)
m1 = atOrZero(mag, x-1, y+1)
case 90: // north and south
m0 = atOrZero(mag, x, y-1)
m1 = atOrZero(mag, x, y+1)
case 135: // north-west and south-east
m0 = atOrZero(mag, x-1, y-1)
m1 = atOrZero(mag, x+1, y+1)
default:
return fmt.Errorf("edge: bad direction (%d, %d): %d", x, y, d)
}
m := mag.Pix[(y-b.Min.Y)*mag.Stride+(x-b.Min.X)*1]
if m > m0 && m > m1 {
m = 0xff
} else if m > m0 || m > m1 {
m = 0x80
} else {
m = 0x00
}
dst.Pix[(y-b.Min.Y)*dst.Stride+(x-b.Min.X)*1] = m
}
}
return nil
}
func diffOp(mag, dir *image.Gray, src image.Image, opX, opY *convolve.SeparableKernel) error {
if src == nil {
return errors.New("graphics: src is nil")
}
b := src.Bounds()
srcg, ok := src.(*image.Gray)
if !ok {
srcg = image.NewGray(b)
draw.Draw(srcg, b, src, b.Min, draw.Src)
}
mx := image.NewGray(b)
if err := convolve.Convolve(mx, srcg, opX); err != nil {
return err
}
my := image.NewGray(b)
if err := convolve.Convolve(my, srcg, opY); err != nil {
return err
}
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
off := (y-mx.Rect.Min.Y)*mx.Stride + (x-mx.Rect.Min.X)*1
cx := float64(mx.Pix[off])
cy := float64(my.Pix[off])
if mag != nil {
off = (y-mag.Rect.Min.Y)*mag.Stride + (x-mag.Rect.Min.X)*1
mag.Pix[off] = uint8(math.Sqrt(cx*cx + cy*cy))
}
if dir != nil {
off = (y-dir.Rect.Min.Y)*dir.Stride + (x-dir.Rect.Min.X)*1
angle := math.Atan(cy / cx)
// Round the angle to 0, 45, 90, or 135 degrees.
angle = math.Mod(angle, 2*math.Pi)
var degree uint8
if angle <= math.Pi/8 {
degree = 0
} else if angle <= math.Pi*3/8 {
degree = 45
} else if angle <= math.Pi*5/8 {
degree = 90
} else if angle <= math.Pi*7/8 {
degree = 135
} else {
degree = 0
}
dir.Pix[off] = degree
}
}
}
return nil
}
func (cm *ComMaker) Convert(src image.Image) *image.Gray {
// Make Grey Img
b := src.Bounds()
gSrc := image.NewGray(b)
draw.Draw(gSrc, b, src, image.ZP, draw.Src)
// Make Smaller
gDst := image.NewGray(cm.bound)
cm.rConv.Convert(gDst, gSrc)
return gDst
}
func TestGrayPlanes(t *testing.T) {
w, h := 256, 256
src := readImage(t, "testdata/gray.png")
ref := image.NewGray(src.Bounds())
err := Convert(ref, src, nil)
expect(t, err, nil)
raw := image.NewGray(image.Rect(0, 0, w*2, h*2))
dst := raw.SubImage(image.Rect(7, 7, 7+w, 7+h))
err = Convert(dst, src, NewBicubicFilter())
expect(t, err, nil)
err = Convert(src, dst, NewBicubicFilter())
expect(t, err, nil)
checkPsnrs(t, ref, src, image.Rectangle{}, []float64{38})
}
func TestSobel(t *testing.T) {
testData := []struct {
desc string
srcb, dstb image.Rectangle
srcPix, dstPix []uint8
}{
{
"sobel 0x0",
image.Rect(0, 0, 0, 0),
image.Rect(0, 0, 0, 0),
[]uint8{},
[]uint8{},
},
{
"sobel 6x6",
image.Rect(-1, -1, 5, 5),
image.Rect(0, 0, 6, 6),
[]uint8{
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x99, 0x99, 0x99, 0x99,
0x00, 0x00, 0x99, 0x99, 0x99, 0x99,
0x00, 0x00, 0x99, 0x99, 0x99, 0x99,
0x00, 0x00, 0x99, 0x99, 0x99, 0x99,
},
[]uint8{
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0xd8, 0xff, 0xff, 0xff, 0xff,
0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
0x00, 0xff, 0xff, 0x00, 0x00, 0x00,
0x00, 0xff, 0xff, 0x00, 0x00, 0x00,
0x00, 0xff, 0xff, 0x00, 0x00, 0x00,
},
},
}
for _, d := range testData {
src := image.NewGray(d.srcb)
src.Pix = d.srcPix
f := Sobel()
dst := image.NewGray(f.Bounds(src.Bounds()))
f.Draw(dst, src, nil)
if !checkBoundsAndPix(dst.Bounds(), d.dstb, dst.Pix, d.dstPix) {
t.Errorf("test [%s] failed: %#v, %#v", d.desc, dst.Bounds(), dst.Pix)
}
}
}
func TestInvert(t *testing.T) {
src := image.NewGray(image.Rect(0, 0, 256, 1))
for i := 0; i <= 255; i++ {
src.Pix[i] = uint8(i)
}
g := New(Invert())
dst := image.NewGray(g.Bounds(src.Bounds()))
g.Draw(dst, src)
for i := 0; i <= 255; i++ {
if dst.Pix[i] != 255-src.Pix[i] {
t.Errorf("InvertColors: index %d: expected %d got %d", i, 255-src.Pix[i], dst.Pix[i])
}
}
}
// newIntegrals returns the integral and the squared integral.
func newIntegrals(src image.Image) (*integral, *integral) {
b := src.Bounds()
srcg, ok := src.(*image.Gray)
if !ok {
srcg = image.NewGray(b)
draw.Draw(srcg, b, src, b.Min, draw.Src)
}
m := integral{
pix: make([]uint64, b.Max.Y*b.Max.X),
stride: b.Max.X,
rect: b,
}
mSq := integral{
pix: make([]uint64, b.Max.Y*b.Max.X),
stride: b.Max.X,
rect: b,
}
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
os := (y-b.Min.Y)*srcg.Stride + x - b.Min.X
om := (y-b.Min.Y)*m.stride + x - b.Min.X
c := uint64(srcg.Pix[os])
m.pix[om] = c
mSq.pix[om] = c * c
}
}
m.integrate()
mSq.integrate()
return &m, &mSq
}
// from fib_test.go
func BenchmarkFractalGeneration(b *testing.B) {
// run the Fib function b.N times
for n := 0; n < b.N; n++ {
im := image.NewGray(image.Rectangle{image.Point{0, 0}, image.Point{1000, 1000}})
GenerateFractal(im)
}
}
func decodeRawBW(r io.Reader, c PNMConfig) (image.Image, error) {
m := image.NewGray(image.Rect(0, 0, c.Width, c.Height))
byteCount := c.Width / 8
if c.Width%8 != 0 {
byteCount += 1
}
row := make([]byte, byteCount)
pos := 0
for y := 0; y < c.Height; y++ {
if _, err := io.ReadFull(r, row); err != nil {
return nil, err
}
bitsLeft := c.Width
for _, b := range row {
n := bitsLeft
if n > 8 {
n = 8
}
unpackByte(m.Pix[pos:pos+n], b)
bitsLeft -= n
pos += n
}
}
return m, nil
}
// makeTestImages generates an RGBA and a grayscale image and returns
// testImages containing the JPEG encoded form as bytes and the expected color
// model of the image when decoded.
func makeTestImages() ([]testImage, error) {
var ims []testImage
w := bytes.NewBuffer(nil)
im1 := image.NewRGBA(image.Rect(0, 0, width, height))
for i := range im1.Pix {
switch {
case i%4 == 3:
im1.Pix[i] = 255
default:
im1.Pix[i] = uint8(i)
}
}
if err := jpeg.Encode(w, im1, nil); err != nil {
return nil, err
}
ims = append(ims, testImage{im: im1, buf: w.Bytes()})
w = bytes.NewBuffer(nil)
im2 := image.NewGray(image.Rect(0, 0, width, height))
for i := range im2.Pix {
im2.Pix[i] = uint8(i)
}
if err := jpeg.Encode(w, im2, nil); err != nil {
return nil, err
}
ims = append(ims, testImage{im: im2, buf: w.Bytes()})
return ims, nil
}
func ExampleDrawer_floydSteinberg() {
const width = 130
const height = 50
im := image.NewGray(image.Rectangle{Max: image.Point{X: width, Y: height}})
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
dist := math.Sqrt(math.Pow(float64(x-width/2), 2)/3+math.Pow(float64(y-height/2), 2)) / (height / 1.5) * 255
var gray uint8
if dist > 255 {
gray = 255
} else {
gray = uint8(dist)
}
im.SetGray(x, y, color.Gray{Y: 255 - gray})
}
}
pi := image.NewPaletted(im.Bounds(), []color.Color{
color.Gray{Y: 255},
color.Gray{Y: 160},
color.Gray{Y: 70},
color.Gray{Y: 35},
color.Gray{Y: 0},
})
draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.ZP)
shade := []string{" ", "░", "▒", "▓", "█"}
for i, p := range pi.Pix {
fmt.Print(shade[p])
if (i+1)%width == 0 {
fmt.Print("\n")
}
}
}
func PlotSpectogram(sr Reader, outpath string, from, to int) error {
d, err := dft(sr, from, to)
if err != nil {
return err
}
// make image
height, width := len(d[0]), len(d)
image := image.NewGray(image.Rect(0, 0, width, height))
// find maximum value in DFT
max := maxAmp(d)
max = math.Log(1 + max)
// plot each point on image
for i, col := range d {
for j, amp := range col {
// Log(Xk+1) will give us a positive value
// Using log here allows low amplitudes to be more visible
bright := uint8(float64(255) * math.Log(1+amp) / max)
image.Set(i, height-j, color.RGBA{bright, bright, bright, 255})
}
}
of, err := os.Create(outpath)
if err != nil {
return err
}
return png.Encode(of, image)
}
func (p *Pane) render(filename string) error {
w := p.w
h := p.h
mtp := 1 / dx
img := image.NewGray(image.Rect(0, 0, w, h))
for y := 0; y < h; y++ {
for x := 0; x < w; x++ {
img.SetGray(x, y, color.Gray{uint8(math.Sqrt(p.coat[y*w+x]) * 80)})
}
}
for _, d := range p.droplets {
drawDroplet(img, d.x*mtp, d.y*mtp, d.r*mtp, d.h*mtp)
}
file, err := os.Create(filename)
if err != nil {
return err
}
defer file.Close()
err = png.Encode(file, img)
if err != nil {
return err
}
return nil
}
func main() {
const order = 8
const width = 1 << order
const margin = 10
bounds := image.Rect(-margin, -margin, width+2*margin, width+2*margin)
im := image.NewGray(bounds)
gBlack := color.Gray{0}
gWhite := color.Gray{255}
draw.Draw(im, bounds, image.NewUniform(gWhite), image.ZP, draw.Src)
for y := 0; y < width; y++ {
for x := 0; x < width; x++ {
if x&y == 0 {
im.SetGray(x, y, gBlack)
}
}
}
f, err := os.Create("sierpinski.png")
if err != nil {
fmt.Println(err)
return
}
if err = png.Encode(f, im); err != nil {
fmt.Println(err)
}
if err = f.Close(); err != nil {
fmt.Println(err)
}
}
// Render draws rune r front the specified font at the specified dpi and scale. It returns a
// grayscale image that is just large enough to contain the rune.
func Render(font *truetype.Font, r rune, dpi, scale float64) (*image.Gray, error) {
glyph := truetype.NewGlyphBuf()
index := font.Index(r)
glyph.Load(font, font.FUnitsPerEm(), index, truetype.FullHinting)
ctx := freetype.NewContext()
boxer := makeBoundingBoxer()
ctx.SetSrc(image.NewUniform(color.White))
ctx.SetDst(boxer)
ctx.SetClip(boxer.largeBounds)
ctx.SetFontSize(250)
ctx.SetDPI(dpi)
ctx.SetFont(font)
if err := glyph.Load(font, font.FUnitsPerEm(), font.Index(r), truetype.FullHinting); err != nil {
return nil, fmt.Errorf("Unable to load glyph: %v\n", err)
}
var rp raster.Point
rp.X = ctx.PointToFix32(0)
rp.Y = ctx.PointToFix32(100)
ctx.DrawString(string(r), rp)
boxer.complete()
g := gift.New(
gift.Resize(int(float64(boxer.Bounds().Dx())*scale+0.5), int(float64(boxer.Bounds().Dy())*scale+0.5), gift.CubicResampling),
)
dst := image.NewGray(g.Bounds(boxer.Bounds()))
g.Draw(dst, boxer)
return dst, nil
}
func NewImageOfTypeRect(src image.Image, bounds image.Rectangle) image.Image {
switch i := src.(type) {
case *image.Alpha:
return image.NewAlpha(bounds)
case *image.Alpha16:
return image.NewAlpha16(bounds)
case *image.Gray:
return image.NewGray(bounds)
case *image.Gray16:
return image.NewGray16(bounds)
case *image.NRGBA:
return image.NewNRGBA(bounds)
case *image.NRGBA64:
return image.NewNRGBA64(bounds)
case *image.Paletted:
return image.NewPaletted(bounds, i.Palette)
case *image.RGBA:
return image.NewRGBA(bounds)
case *image.RGBA64:
return image.NewRGBA64(bounds)
case *image.YCbCr:
return image.NewYCbCr(bounds, i.SubsampleRatio)
}
panic("Unknown image type")
}
func TestHoughLines(t *testing.T) {
timg := image.NewGray(image.Rect(0, 0, 700, 500))
timg.SetGray(10, 10, color.Gray{1})
timg.SetGray(200, 10, color.Gray{1})
timg.SetGray(400, 10, color.Gray{1})
timg.SetGray(10, 200, color.Gray{1})
timg.SetGray(10, 400, color.Gray{1})
lines := houghLines(*timg, nil, 0, 10)
if !assert.Len(t, lines, 6) {
t.FailNow()
}
expectedLines := []polarLine{
polarLine{Theta: 1.570796, Distance: 10, Count: 3},
polarLine{Theta: 0.000000, Distance: 10, Count: 3},
polarLine{Theta: 0.785398, Distance: 148, Count: 2},
polarLine{Theta: 0.453786, Distance: 184, Count: 2},
polarLine{Theta: 1.117011, Distance: 184, Count: 2},
polarLine{Theta: 0.785398, Distance: 290, Count: 2},
}
for i, line := range lines {
expected := expectedLines[i]
thetaOk := assert.InDelta(t, expected.Theta, line.Theta, 0.0001)
distanceOk := assert.Equal(t, expected.Distance, line.Distance)
countOk := assert.Equal(t, expected.Count, line.Count)
if !thetaOk || !distanceOk || !countOk {
t.Fatalf("%v expected to equal %v", line, expected)
}
}
}
func writeToJP() {
imgRect := image.Rect(0, 0, gridSize*10, gridSize*10)
img := image.NewGray(imgRect)
draw.Draw(img, img.Bounds(), &image.Uniform{color.White}, image.ZP, draw.Src)
for x := 0; x < gridSize; x++ {
for y := 0; y < gridSize; y++ {
fill := &image.Uniform{color.White}
if Env[x][y] == -1 {
fill = &image.Uniform{color.Black}
} else if Env[x][y] > 1 {
c := color.Gray{uint8(Env[x][y] * 20)}
fill = &image.Uniform{c}
}
draw.Draw(img, image.Rect((x-1)*10, (y-1)*10, x*10, y*10), fill, image.ZP, draw.Src)
}
}
buf := bytes.Buffer{}
// ok, write out the data into the new JPEG file
err := gif.Encode(&buf, img, nil)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
tmpimg, err := gif.Decode(&buf)
if err != nil {
log.Printf("Skipping frame due to weird error reading the temporary gif :%s", err)
}
frames = append(frames, tmpimg.(*image.Paletted))
}
// DifferenceHash computes the difference hash of an image.
func DifferenceHash(source image.Image) uint64 {
const sw, sh, hw, hh = 9, 8, 8, 8
// Convert the image to the grayscale colourspace.
bounds := source.Bounds()
width, height := bounds.Max.X, bounds.Max.Y
gray := image.NewGray(source.Bounds())
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
gray.Set(x, y, source.At(x, y))
}
}
// Resize the image.
shrunk := resize.Resize(sw, sh, gray, resize.NearestNeighbor).(*image.Gray)
// Compute the difference hash.
var hash uint64
for y := 0; y < hh; y++ {
for x := 0; x < hw; x++ {
if shrunk.GrayAt(x, y).Y < shrunk.GrayAt(x+1, y).Y {
hash |= 1 << uint64((y*hw)+x)
}
}
}
return hash
}
// TestWriteGrayscale tests that a grayscale images survives a round-trip
// through encode/decode cycle.
func TestWriteGrayscale(t *testing.T) {
m0 := image.NewGray(image.Rect(0, 0, 32, 32))
for i := range m0.Pix {
m0.Pix[i] = uint8(i)
}
var buf bytes.Buffer
if err := Encode(&buf, m0, nil); err != nil {
t.Fatal(err)
}
m1, err := Decode(&buf)
if err != nil {
t.Fatal(err)
}
if m0.Bounds() != m1.Bounds() {
t.Fatalf("bounds differ: %v and %v", m0.Bounds(), m1.Bounds())
}
if _, ok := m1.(*image.Gray); !ok {
t.Errorf("got %T, want *image.Gray", m1)
}
// Compare the average delta to the tolerance level.
want := int64(2 << 8)
if got := averageDelta(m0, m1); got > want {
t.Errorf("average delta too high; got %d, want <= %d", got, want)
}
}
func main() {
flag.Parse()
rand.Seed(time.Now().UTC().UnixNano())
out, err := os.Create(*outfile)
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %v\n", err)
os.Exit(1)
}
imgRect := image.Rect(0, 0, 200, 200)
img := image.NewGray(imgRect)
draw.Draw(img, img.Bounds(), &image.Uniform{color.White}, image.ZP, draw.Src)
for y := 0; y < 200; y += 10 {
for x := 0; x < 200; x += 10 {
fill := &image.Uniform{color.Black}
if rand.Intn(10)%2 == 0 {
fill = &image.Uniform{color.White}
}
draw.Draw(img, image.Rect(x, y, x+10, y+10), fill, image.ZP, draw.Src)
}
}
err = png.Encode(out, img)
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %v\n", err)
os.Exit(2)
}
fmt.Printf("Wrote random image to \"%s\"\n", *outfile)
os.Exit(0)
}
func hough(im image.Image, ntx, mry int) draw.Image {
nimx := im.Bounds().Max.X
mimy := im.Bounds().Max.Y
mry = int(mry/2) * 2
him := image.NewGray(image.Rect(0, 0, ntx, mry))
draw.Draw(him, him.Bounds(), image.NewUniform(color.White),
image.ZP, draw.Src)
rmax := math.Hypot(float64(nimx), float64(mimy))
dr := rmax / float64(mry/2)
dth := math.Pi / float64(ntx)
for jx := 0; jx < nimx; jx++ {
for iy := 0; iy < mimy; iy++ {
col := color.GrayModel.Convert(im.At(jx, iy)).(color.Gray)
if col.Y == 255 {
continue
}
for jtx := 0; jtx < ntx; jtx++ {
th := dth * float64(jtx)
r := float64(jx)*math.Cos(th) + float64(iy)*math.Sin(th)
iry := mry/2 - int(math.Floor(r/dr+.5))
col = him.At(jtx, iry).(color.Gray)
if col.Y > 0 {
col.Y--
him.SetGray(jtx, iry, col)
}
}
}
}
return him
}
// makeImg allocates and initializes the destination image.
func (d *decoder) makeImg(h0, v0, mxx, myy int) {
if d.nComp == nGrayComponent {
d.img1 = image.NewGray(8*mxx, 8*myy)
d.img1.Rect = image.Rect(0, 0, d.width, d.height)
return
}
var subsampleRatio ycbcr.SubsampleRatio
n := h0 * v0
switch n {
case 1:
subsampleRatio = ycbcr.SubsampleRatio444
case 2:
subsampleRatio = ycbcr.SubsampleRatio422
case 4:
subsampleRatio = ycbcr.SubsampleRatio420
default:
panic("unreachable")
}
b := make([]byte, mxx*myy*(1*8*8*n+2*8*8))
d.img3 = &ycbcr.YCbCr{
Y: b[mxx*myy*(0*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+0*8*8)],
Cb: b[mxx*myy*(1*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+1*8*8)],
Cr: b[mxx*myy*(1*8*8*n+1*8*8) : mxx*myy*(1*8*8*n+2*8*8)],
SubsampleRatio: subsampleRatio,
YStride: mxx * 8 * h0,
CStride: mxx * 8,
Rect: image.Rect(0, 0, d.width, d.height),
}
}