1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "ip.rsh"
18#pragma rs_fp_relaxed
19
20rs_allocation histogramValues;
21static float3 scale;
22
23static uchar4 estimateWhite() {
24    int min_r = -1, min_g = -1, min_b = -1;
25    int max_r =  0, max_g =  0, max_b =  0;
26    int sum_r =  0, sum_g =  0, sum_b =  0;
27
28    for (int i = 1; i < 255; i++) {
29        int4 hv = rsGetElementAt_int4(histogramValues, i);
30        int r = hv.r;
31        int g = hv.g;
32        int b = hv.b;
33        sum_r += r;
34        sum_g += g;
35        sum_b += b;
36
37        if (r>0){
38            if (min_r < 0) min_r = i;
39            max_r = i;
40        }
41        if (g>0){
42            if (min_g < 0) min_g = i;
43            max_g = i;
44        }
45        if (b>0){
46            if (min_b < 0) min_b = i;
47            max_b = i;
48        }
49    }
50
51    int sum15r = 0, sum15g = 0, sum15b = 0;
52    int count15r = 0, count15g = 0, count15b = 0;
53    int tmp_r = 0, tmp_g = 0, tmp_b = 0;
54
55    for (int i = 254; i >0; i--) {
56        int4 hv = rsGetElementAt_int4(histogramValues, i);
57        int r = hv.r;
58        int g = hv.g;
59        int b = hv.b;
60        tmp_r += r;
61        tmp_g += g;
62        tmp_b += b;
63
64        if ((tmp_r > sum_r/20) && (tmp_r < sum_r/5)) {
65            sum15r += r*i;
66            count15r += r;
67        }
68        if ((tmp_g > sum_g/20) && (tmp_g < sum_g/5)) {
69            sum15g += g*i;
70            count15g += g;
71        }
72        if ((tmp_b > sum_b/20) && (tmp_b < sum_b/5)) {
73            sum15b += b*i;
74            count15b += b;
75        }
76
77    }
78
79    uchar4 out;
80
81    if ((count15r>0) && (count15g>0) && (count15b>0) ){
82        out.r = sum15r/count15r;
83        out.g = sum15g/count15g;
84        out.b = sum15b/count15b;
85    }else {
86        out.r = out.g = out.b = 255;
87    }
88
89    return out;
90
91}
92
93void prepareWhiteBalance() {
94    uchar4 estimation = estimateWhite();
95    int minimum = min(estimation.r, min(estimation.g, estimation.b));
96    int maximum = max(estimation.r, max(estimation.g, estimation.b));
97    float avg = (minimum + maximum) / 2.f;
98
99    scale.r =  avg / estimation.r;
100    scale.g =  avg / estimation.g;
101    scale.b =  avg / estimation.b;
102}
103
104uchar4 RS_KERNEL whiteBalanceKernel(uchar4 in) {
105    float3 t = convert_float3(in.rgb);
106    t *= scale;
107    t = min(t, 255.f);
108
109    uchar4 out;
110    out.rgb = convert_uchar3(t);
111    out.a = 255;
112    return out;
113}
114