bmcv_image_pyramid_down

该接口实现图像高斯金字塔操作中的向下采样。

接口形式：

bm_status_t bmcv_image_pyramid_down(
         bm_handle_t handle,
         bm_image input,
         bm_image output);

参数说明：

bm_handle_t handle

输入参数。 bm_handle 句柄。
bm_image input

输入参数。输入图像 bm_image，bm_image 需要外部调用 bmcv_image_create 创建。bm_image 的内存可以使用 bm_image_alloc_dev_mem 或者bm_image_copy_host_to_device 来开辟新的内存，或者使用 bmcv_image_attach 来 attach 已有的内存。
bm_image output

输出参数。输出图像 bm_image，bm_image 需要外部调用 bmcv_image_create 创建。bm_image的内存可以使用 bm_image_alloc_dev_mem 或者bm_image_copy_host_to_device 来开辟新的内存，或者使用 bmcv_image_attach 来 attach 已有的内存。

返回值说明：

BM_SUCCESS: 成功
其他:失败

格式支持：

该接口目前支持以下 image_format与data_type:

num	image_format	data_type
1	FORMAT_GRAY	DATA_TYPE_EXT_1N_BYTE

代码示例：

int height = 1080;
int width = 1920;
int ow = height / 2;
int oh = width / 2;
int channel = 1;
unsigned char* input_data = new unsigned char [width * height * channel];
unsigned char* output_tpu = new unsigned char [ow * oh * channel];
unsigned char* output_ocv = new unsigned char [ow * oh * channel];

for (int i = 0; i < height * channel; i++) {
    for (int j = 0; j < width; j++) {
        input_data[i * width + j] = rand() % 100;
    }
}

bm_handle_t handle;
bm_status_t ret = bm_dev_request(&handle, 0);
if (ret != BM_SUCCESS) {
    printf("Create bm handle failed. ret = %d\n", ret);
    return -1;
}
bm_image_format_ext fmt = FORMAT_GRAY;
bm_image img_i;
bm_image img_o;
bm_image_create(handle, height, width, fmt, DATA_TYPE_EXT_1N_BYTE, &img_i);
bm_image_create(handle, oh, ow, fmt, DATA_TYPE_EXT_1N_BYTE, &img_o);
bm_image_alloc_dev_mem(img_i);
bm_image_alloc_dev_mem(img_o);
bm_image_copy_host_to_device(img_i, (void **)(&input));

struct timeval t1, t2;
gettimeofday_(&t1);
bmcv_image_pyramid_down(handle, img_i, img_o);
gettimeofday_(&t2);
cout << "pyramid down TPU using time: " << ((t2.tv_sec - t1.tv_sec) * 1000000 + t2.tv_usec - t1.tv_usec) << "us" << endl;

bm_image_copy_device_to_host(img_o, (void **)(&output));
bm_image_destroy(img_i);
bm_image_destroy(img_o);
bm_dev_free(handle);