You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
58 lines
2.2 KiB
58 lines
2.2 KiB
/*
|
|
* Copyright 2021 Google LLC
|
|
*
|
|
* 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.google.ux.material.libmonet.quantize;
|
|
|
|
import java.util.Map;
|
|
import java.util.Set;
|
|
|
|
/**
|
|
* An image quantizer that improves on the quality of a standard K-Means algorithm by setting the
|
|
* K-Means initial state to the output of a Wu quantizer, instead of random centroids. Improves on
|
|
* speed by several optimizations, as implemented in Wsmeans, or Weighted Square Means, K-Means with
|
|
* those optimizations.
|
|
*
|
|
* <p>This algorithm was designed by M. Emre Celebi, and was found in their 2011 paper, Improving
|
|
* the Performance of K-Means for Color Quantization. https://arxiv.org/abs/1101.0395
|
|
*/
|
|
public final class QuantizerCelebi {
|
|
private QuantizerCelebi() {}
|
|
|
|
/**
|
|
* Reduce the number of colors needed to represented the input, minimizing the difference between
|
|
* the original image and the recolored image.
|
|
*
|
|
* @param pixels Colors in ARGB format.
|
|
* @param maxColors The number of colors to divide the image into. A lower number of colors may be
|
|
* returned.
|
|
* @return Map with keys of colors in ARGB format, and values of number of pixels in the original
|
|
* image that correspond to the color in the quantized image.
|
|
*/
|
|
public static Map<Integer, Integer> quantize(int[] pixels, int maxColors) {
|
|
QuantizerWu wu = new QuantizerWu();
|
|
QuantizerResult wuResult = wu.quantize(pixels, maxColors);
|
|
|
|
Set<Integer> wuClustersAsObjects = wuResult.colorToCount.keySet();
|
|
int index = 0;
|
|
int[] wuClusters = new int[wuClustersAsObjects.size()];
|
|
for (Integer argb : wuClustersAsObjects) {
|
|
wuClusters[index++] = argb;
|
|
}
|
|
|
|
return QuantizerWsmeans.quantize(pixels, wuClusters, maxColors);
|
|
}
|
|
}
|