samples/risp4ml/isp_stages/downscale.h

/*
 * Copyright 2022 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.
 */

#ifndef SAMPLES_RISP4ML_ISP_STAGES_DOWNSCALE_H_
#define SAMPLES_RISP4ML_ISP_STAGES_DOWNSCALE_H_

#include "samples/risp4ml/common/image.h"

#ifdef __cplusplus
extern "C" {
#endif  // __cplusplus

typedef struct {
  bool enable;
  // scale_precision is the number of fractional bits used for scale factors and
  // initial offsets
  uint32_t scale_precision;
  // interpolate_precision is the number of fractional bits used for
  // interpolation weights
  uint32_t interpolate_precision;
  // interpolate_shift is the shift for pixel value before interpolation to
  // avoid rounding error.
  uint32_t interpolate_shift;
  uint32_t scale_fixed_one;
  uint32_t scale_fraction_mask;
  uint32_t weight_shift;

  // hor_scale_factor and ver_scale_factor are the downscaling ratios between
  // input size and output size
  // Example: Running the scaler on 4x4 image with hor_scale=2 and ver_scale=2
  // will result in 2x2 image
  // TODO(b/179302796): convert scaling factors to be floats.
  // Use FloatToFixedPoint() to facilitate this.
  uint32_t hor_scale_factor;
  uint32_t ver_scale_factor;

  // hor_initial_offset and ver_initial_offset are the offset of the first
  // output pixel from the first input pixel in each direction respectively
  uint32_t ver_initial_offset;
  uint32_t hor_initial_offset;
} DownscaleParams;

void set_downscale_param(DownscaleParams* params);

void set_downscale_factor(Image* input, ImageU8* output);

void downscale_process(Image* input, ImageU8* output);

#ifdef __cplusplus
}  // extern "C"
#endif  // __cplusplus

#endif  // SAMPLES_RISP4ML_ISP_STAGES_DOWNSCALE_H_