java/tests/ImageProcessing_jb/src/com/android/rs/image/contrast.rs


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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 float brightM = 0.f;
static float brightC = 0.f;

void setBright(float v) {
    brightM = pow(2.f, v / 100.f);
    brightC = 127.f - brightM * 127.f;
}

uchar4 __attribute__((kernel)) contrast(uchar4 in) {
    float3 v = convert_float3(in.rgb) * brightM + brightC;
    uchar4 o;
    o.rgb = convert_uchar3(clamp(v, 0.f, 255.f));
    o.a = 0xff;
    return o;
}