risp4ml/isp_stages/dg.c

/*
 * Copyright 2023 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.
 */

#include "risp4ml/isp_stages/dg.h"

#include "risp4ml/common/utils.h"

static const uint16_t kDgFractional = kRawPipelineFraction;
static const uint16_t kDgUnityGain = 1 << kDgFractional;
static DgParams dg_params = {
    .enable = true,
    .gains = {kDgUnityGain, kDgUnityGain, kDgUnityGain, kDgUnityGain}};

void set_dg_params(DgParams* params) { dg_params = *params; }

void dg_process(Image* img) {
  if (!dg_params.enable) return;

  for (uint16_t y = 0; y < img->height; ++y) {
    pixel_type_t* line = image_row(img, 0, y);

    for (uint16_t x = 0; x < img->width; ++x) {
      BayerIndex bayer_index = GetBayerIndex(kBayerType, x, y);
      // + (1 << (kDgFractional -1)) adds 0.5 for more accurate rounding
      uint32_t scaled_pixel = (uint32_t)line[x] * dg_params.gains[bayer_index] +
                              (1 << (kDgFractional - 1));

      line[x] = (pixel_type_t)Clamp(scaled_pixel >> kDgFractional, 0,
                                    kRawPipelineMaxVal);
    }
  }
}