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/*
* Copyright (C) 2012 The Android Open Source Project
*
* 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.
*/
#include "ip.rsh"
#pragma rs_fp_relaxed
static int histR[256] = {0}, histG[256] = {0}, histB[256] = {0};
rs_allocation histogramSource;
uint32_t histogramHeight;
uint32_t histogramWidth;
static float3 scale;
static uchar4 estimateWhite() {
for (int i = 0; i < 256; i++) {
histR[i] = 0; histG[i] = 0; histB[i] = 0;
}
for (uint32_t i = 0; i < histogramHeight; i++) {
for (uint32_t j = 0; j < histogramWidth; j++) {
uchar4 in = rsGetElementAt_uchar4(histogramSource, j, i);
histR[in.r]++;
histG[in.g]++;
histB[in.b]++;
}
}
int min_r = -1, min_g = -1, min_b = -1;
int max_r = 0, max_g = 0, max_b = 0;
int sum_r = 0, sum_g = 0, sum_b = 0;
for (int i = 1; i < 255; i++) {
int r = histR[i];
int g = histG[i];
int b = histB[i];
sum_r += r;
sum_g += g;
sum_b += b;
if (r>0){
if (min_r < 0) min_r = i;
max_r = i;
}
if (g>0){
if (min_g < 0) min_g = i;
max_g = i;
}
if (b>0){
if (min_b < 0) min_b = i;
max_b = i;
}
}
int sum15r = 0, sum15g = 0, sum15b = 0;
int count15r = 0, count15g = 0, count15b = 0;
int tmp_r = 0, tmp_g = 0, tmp_b = 0;
for (int i = 254; i >0; i--) {
int r = histR[i];
int g = histG[i];
int b = histB[i];
tmp_r += r;
tmp_g += g;
tmp_b += b;
if ((tmp_r > sum_r/20) && (tmp_r < sum_r/5)) {
sum15r += r*i;
count15r += r;
}
if ((tmp_g > sum_g/20) && (tmp_g < sum_g/5)) {
sum15g += g*i;
count15g += g;
}
if ((tmp_b > sum_b/20) && (tmp_b < sum_b/5)) {
sum15b += b*i;
count15b += b;
}
}
uchar4 out;
if ((count15r>0) && (count15g>0) && (count15b>0) ){
out.r = sum15r/count15r;
out.g = sum15g/count15g;
out.b = sum15b/count15b;
}else {
out.r = out.g = out.b = 255;
}
return out;
}
void prepareWhiteBalance() {
uchar4 estimation = estimateWhite();
int minimum = min(estimation.r, min(estimation.g, estimation.b));
int maximum = max(estimation.r, max(estimation.g, estimation.b));
float avg = (minimum + maximum) / 2.f;
scale.r = avg/estimation.r;
scale.g = avg/estimation.g;
scale.b = avg/estimation.b;
}
uchar4 RS_KERNEL whiteBalanceKernel(uchar4 in) {
float3 t = convert_float3(in.rgb);
t *= scale;
t = min(t, 255.f);
uchar4 out;
out.rgb = convert_uchar3(t);
out.a = 255;
return out;
}
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