DataAugmentation
"""
AdjustBrightness(δ = 0.2)
AdjustBrightness(distribution)
Adjust the brightness of an image by a factor chosen uniformly
from `f ∈ [1-δ, 1+δ]` by multiplying each color channel by `f`.
You can also pass any `Distributions.Sampleable` from which the
factor is selected.
Pixels are clamped to [0,1] unless `clamp=false` is passed.
## Example
{cell=AdjustBrightness}
```julia
using DataAugmentation, TestImages
item = Image(testimage("lighthouse"))
tfm = AdjustBrightness(0.2)
titems = [apply(tfm, item) for _ in 1:8]
showgrid(titems; ncol = 4, npad = 16)
```
"""
struct
AdjustBrightness
{
S
<:
Sampleable
}
<:
Transform
dist
::
S
clamp
::
Bool
end
AdjustBrightness
(
f
::
Real
;
clamp
::
Bool
=
true
)
=
AdjustBrightness
(
Uniform
(
max
(
0
,
1
-
f
)
,
1
+
f
)
,
clamp
)
getrandstate
(
tfm
::
AdjustBrightness
)
=
rand
(
tfm
.
dist
)
function
apply
(
tfm
::
AdjustBrightness
,
item
::
Image
;
randstate
=
getrandstate
(
tfm
)
)
factor
=
randstate
return
setdata
(
item
,
adjustbrightness
(
itemdata
(
item
)
,
factor
,
tfm
.
clamp
)
)
end
function
apply!
(
buf
,
tfm
::
AdjustBrightness
,
item
::
Image
;
randstate
=
getrandstate
(
tfm
)
)
factor
=
randstate
adjustbrightness!
(
itemdata
(
buf
)
,
itemdata
(
item
)
,
factor
,
tfm
.
clamp
)
return
buf
end
function
adjustbrightness
(
img
,
factor
,
clamp
)
return
adjustbrightness!
(
copy
(
img
)
,
factor
,
clamp
)
end
adjustbrightness!
(
img
,
factor
,
clamp
)
=
adjustbrightness!
(
img
,
img
,
factor
,
clamp
)TODO: add methods for non-RGB/Gray images
function
adjustbrightness!
(
dst
::
AbstractArray
{
U
}
,
img
::
AbstractArray
{
T
}
,
factor
,
clamp
)
where
{
T
,
U
}
map!
(
dst
,
img
)
do
x
convert
(
U
,
clamp
?
clamp01
(
x
*
factor
)
:
x
*
factor
)
end
end
"""
AdjustContrast(factor = 0.2)
AdjustContrast(distribution)
Adjust the contrast of an image by a factor chosen uniformly
from `f ∈ [1-δ, 1+δ]`.
Pixels `c` are transformed `c + μ*(1-f)` where `μ` is the mean color
of the image.
You can also pass any `Distributions.Sampleable` from which the
factor is selected.
Pixels are clamped to [0,1] unless `clamp=false` is passed.
## Example
{cell=AdjustBrightness}
```julia
using DataAugmentation, TestImages
item = Image(testimage("lighthouse"))
tfm = AdjustContrast(0.2)
titems = [apply(tfm, item) for _ in 1:8]
showgrid(titems; ncol = 4, npad = 16)
```
"""
struct
AdjustContrast
{
S
<:
Sampleable
}
<:
Transform
dist
::
S
clamp
::
Bool
end
AdjustContrast
(
f
::
Real
;
clamp
::
Bool
=
true
)
=
AdjustContrast
(
Uniform
(
max
(
0
,
1
-
f
)
,
1
+
f
)
,
clamp
)
getrandstate
(
tfm
::
AdjustContrast
)
=
rand
(
tfm
.
dist
)
function
apply
(
tfm
::
AdjustContrast
,
item
::
Image
;
randstate
=
getrandstate
(
tfm
)
)
factor
=
randstate
return
setdata
(
item
,
adjustcontrast
(
itemdata
(
item
)
,
factor
,
tfm
.
clamp
)
)
end
function
apply!
(
buf
,
tfm
::
AdjustContrast
,
item
::
Image
;
randstate
=
getrandstate
(
tfm
)
)
factor
=
randstate
adjustcontrast!
(
itemdata
(
buf
)
,
itemdata
(
item
)
,
factor
,
tfm
.
clamp
)
return
buf
end
function
adjustcontrast
(
img
,
factor
,
clamp
)
return
adjustcontrast!
(
copy
(
img
)
,
factor
,
clamp
)
endTODO: add methods for non-RGB/Gray images
function
adjustcontrast!
(
dst
::
AbstractArray
{
U
}
,
img
::
AbstractArray
{
T
}
,
factor
,
clamp
)
where
{
T
,
U
}
μ
=
mean
(
img
)
map!
(
dst
,
img
)
do
x
convert
(
U
,
clamp
?
clamp01
(
x
+
μ
*
(
1
-
factor
)
)
:
x
+
μ
*
(
1
-
factor
)
)
end
end
adjustcontrast!
(
img
,
factor
,
clamp
)
=
adjustcontrast!
(
img
,
img
,
factor
,
clamp
)