Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Make gaussian blur using separable convolution #71

Merged
merged 1 commit into from
Jul 31, 2019
Merged

Make gaussian blur using separable convolution #71

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
27 changes: 13 additions & 14 deletions blur/blur.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -35,19 +35,18 @@ func Gaussian(src image.Image, radius float64) *image.RGBA {
return clone.AsRGBA(src)
}

// Create the 1-d gaussian kernel
length := int(math.Ceil(2*radius + 1))
k := convolution.NewKernel(length, length)

gaussianFn := func(x, y, sigma float64) float64 {
return math.Exp(-(x*x/sigma + y*y/sigma))
}

for x := 0; x < length; x++ {
for y := 0; y < length; y++ {
k.Matrix[y*length+x] = gaussianFn(float64(x)-radius, float64(y)-radius, 4*radius)

}
}

return convolution.Convolve(src, k.Normalized(), &convolution.Options{Bias: 0, Wrap: false, KeepAlpha: false})
k := convolution.NewKernel(length, 1)
for i, x := 0, -radius; i < length; i, x = i+1, x+1 {
k.Matrix[i] = math.Exp(-(x*x/4/radius))
}
normK := k.Normalized()

// Perform separable convolution
options := convolution.Options{Bias: 0, Wrap: false, KeepAlpha: false}
result := convolution.Convolve(src, normK, &options)
result = convolution.Convolve(result, normK.Transposed(), &options)

return result
}
10 changes: 5 additions & 5 deletions blur/blur_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -128,9 +128,9 @@ func TestGaussianBlur(t *testing.T) {
Rect: image.Rect(0, 0, 3, 3),
Stride: 3 * 4,
Pix: []uint8{
0xb1, 0xb1, 0xb1, 0xff, 0xbd, 0xbd, 0xbd, 0xff, 0xcc, 0xcc, 0xcc, 0xff,
0x4d, 0x4d, 0x4d, 0xff, 0x68, 0x68, 0x68, 0xff, 0x8b, 0x8b, 0x8b, 0xff,
0x0, 0x0, 0x0, 0xff, 0x26, 0x26, 0x26, 0xff, 0x59, 0x59, 0x59, 0xff,
0xb1, 0xb1, 0xb1, 0xff, 0xbc, 0xbc, 0xbc, 0xff, 0xcc, 0xcc, 0xcc, 0xff,
0x4d, 0x4d, 0x4d, 0xff, 0x68, 0x68, 0x68, 0xff, 0x8b, 0x8b, 0x8b, 0xff,
0x0, 0x0, 0x0, 0xff, 0x25, 0x25, 0x25, 0xff, 0x58, 0x58, 0x58, 0xff,
},
},
},
Expand All @@ -157,10 +157,10 @@ func TestGaussianBlur(t *testing.T) {
},
}

for _, c := range cases {
for i, c := range cases {
actual := Gaussian(c.value, c.radius)
if !util.RGBAImageEqual(actual, c.expected) {
t.Errorf("%s: expected: %#v, actual: %#v", "GaussianBlur", c.expected, actual)
t.Errorf("%s %d: expected: %#v, actual: %#v", "GaussianBlur", i, c.expected, actual)
}
}
}
16 changes: 16 additions & 0 deletions convolution/kernel.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ type Matrix interface {
Normalized() Matrix
MaxX() int
MaxY() int
Transposed() Matrix
}

// NewKernel returns a kernel of the provided length.
Expand Down Expand Up @@ -63,6 +64,21 @@ func (k *Kernel) At(x, y int) float64 {
return k.Matrix[y*k.Width+x]
}

// Transposed returns a new Kernel that has the columns as rows and vice versa
func (k *Kernel) Transposed() Matrix {
w := k.Width;
h := k.Height;
nk := NewKernel(h, w)

for x := 0; x<w; x++ {
for y := 0; y<h; y++ {
nk.Matrix[x*h + y] = k.Matrix[y*w + x];
}
}

return nk
}

// String returns the string representation of the matrix.
func (k *Kernel) String() string {
result := ""
Expand Down
80 changes: 80 additions & 0 deletions convolution/kernel_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,86 @@ func TestKernelNormalized(t *testing.T) {
}
}

func TestKernelTransposed(t *testing.T) {
cases := []struct {
desc string
kernel *Kernel
expected *Kernel
}{
{
desc: "all zero",
kernel: &Kernel{[]float64{
0, 0, 0,
0, 0, 0,
0, 0, 0,
}, 3, 3},
expected: &Kernel{[]float64{
0, 0, 0,
0, 0, 0,
0, 0, 0,
}, 3, 3},
},
{
desc: "one element",
kernel: &Kernel{[]float64{
0, 0, 0,
0, 1, 0,
0, 0, 0,
}, 3, 3},
expected: &Kernel{[]float64{
0, 0, 0,
0, 1, 0,
0, 0, 0,
}, 3, 3},
},
{
desc: "diagonal",
kernel: &Kernel{[]float64{
1, 0, 0,
0, 1, 0,
0, 0, 1,
}, 3, 3},
expected: &Kernel{[]float64{
1, 0, 0,
0, 1, 0,
0, 0, 1,
}, 3, 3},
},
{
desc: "3x2",
kernel: &Kernel{[]float64{
1, 1, 1,
0, 1, 0,
}, 3, 2},
expected: &Kernel{[]float64{
1, 0,
1, 1,
1, 0,
}, 2, 3},
},
{
desc: "5x1",
kernel: &Kernel{[]float64{
1, 1, 1, 0, 1,
}, 5, 1},
expected: &Kernel{[]float64{
1,
1,
1,
0,
1,
}, 1, 5},
},
}

for i, c := range cases {
actual := c.kernel.Transposed()
if !kernelEqual(actual.(*Kernel), c.expected) {
t.Errorf("%s case #%d: expected: %#v, actual: %#v", "KernelTransposed "+c.desc, i, c.expected, actual)
}
}
}

func TestKernelString(t *testing.T) {
cases := []struct {
kernel *Kernel
Expand Down
10 changes: 5 additions & 5 deletions effect/effect_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -816,9 +816,9 @@ func TestUnsharpMask(t *testing.T) {
Rect: image.Rect(0, 0, 3, 3),
Stride: 3 * 4,
Pix: []uint8{
0xFF, 0x0, 0x0, 0xFF, 0xFF, 0xFF, 0x0, 0xFF, 0xFF, 0x47, 0x25, 0xFF,
0x0, 0xD2, 0x9A, 0xFF, 0xA9, 0x0, 0xFF, 0xFF, 0x36, 0x4D, 0x93, 0xFF,
0x0, 0x0, 0xDA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x0, 0xD4, 0xFF,
0xFF, 0x0, 0x0, 0xFF, 0xFF, 0xFF, 0x0, 0xFF, 0xFF, 0x48, 0x26, 0xFF,
0x0, 0xD2, 0x9A, 0xFF, 0xAA, 0x0, 0xFF, 0xFF, 0x36, 0x4D, 0x93, 0xFF,
0x0, 0x0, 0xDA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x0, 0xD5, 0xFF,
},
},
},
Expand All @@ -838,8 +838,8 @@ func TestUnsharpMask(t *testing.T) {
Rect: image.Rect(0, 0, 3, 3),
Stride: 3 * 4,
Pix: []uint8{
0xFF, 0x0, 0x0, 0xFF, 0xFF, 0xFF, 0x0, 0xFF, 0xFF, 0x43, 0x32, 0xFF,
0xB, 0xA9, 0x8D, 0xFF, 0xAD, 0x0, 0xFA, 0xFF, 0x5B, 0x46, 0x89, 0xFF,
0xFF, 0x0, 0x0, 0xFF, 0xFF, 0xFF, 0x0, 0xFF, 0xFF, 0x44, 0x33, 0xFF,
0xB, 0xA9, 0x8D, 0xFF, 0xAE, 0x0, 0xFA, 0xFF, 0x5B, 0x46, 0x89, 0xFF,
0x0, 0x0, 0xC2, 0xFF, 0xFF, 0xFF, 0xF3, 0xFF, 0xFF, 0x0, 0xBF, 0xFF,
},
},
Expand Down