com.intel.analytics.bigdl.dataset.image.Lighting.scala Maven / Gradle / Ivy
/*
* Copyright 2016 The BigDL Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.intel.analytics.bigdl.dataset.image
import com.intel.analytics.bigdl.dataset.Transformer
import com.intel.analytics.bigdl.tensor.{Storage, Tensor}
import com.intel.analytics.bigdl.utils.RandomGenerator.RNG
import scala.collection.Iterator
object Lighting {
def apply(): Lighting = {
new Lighting()
}
}
/**
* Lighting noise for data augmentation
*
* Krizhevsky et al. proposed fancy PCA when training the famous Alex-Net in 2012
* Fancy PCA alters the intensities of the RGB channels in training images
* For each training image, add the corresponding quantity to each RGB image pixel
*/
class Lighting extends Transformer[LabeledBGRImage, LabeledBGRImage] {
val alphastd = 0.1f
val eigval = Tensor[Float](Storage(Array(0.2175f, 0.0188f, 0.0045f)), 1, Array(3))
val eigvec = Tensor[Float](Storage(Array(-0.5675f, 0.7192f, 0.4009f,
-0.5808f, -0.0045f, -0.8140f,
-0.5836f, -0.6948f, 0.4203f)), 1, Array(3, 3))
def lighting(input: Array[Float]): Unit = {
if (alphastd != 0) {
val alpha = Tensor[Float](3).apply1(_ => RNG.uniform(0, alphastd).toFloat)
val rgb = eigvec.clone
.cmul(alpha.view(1, 3).expand(Array(3, 3)))
.cmul(eigval.view(1, 3).expand(Array(3, 3)))
.sum(2).squeeze
var i = 0
while (i < input.length) {
input(i) = input(i) + rgb.storage().array()(0)
input(i + 1) = input(i + 1) + rgb.storage().array()(1)
input(i + 2) = input(i + 2) + rgb.storage().array()(2)
i += 3
}
}
}
override def apply(prev: Iterator[LabeledBGRImage]): Iterator[LabeledBGRImage] = {
prev.map(img => {
lighting(img.content)
img
})
}
}