OpenExplorer
Guide
Horizon Smart Car Developer Community
Horizon Official Website
Guide
Horizon Smart Car Developer Community
Horizon Official Website
English

Box Filter

The box filter is a low-pass filter that generates pixel values by weighting and averaging the pixels around a pixel point, and is commonly used to eliminate image details, remove noise, and blur edges.

Operator Effect

Input ImageParameterOutput Image
imagekernelHeight = 3
kernelWidth = 3
pointLocX = -1
pointLocY = -1
normalize = 1
borderType = 0		image

Principle

Box filtering uses the following filter kernel, which weights the pixel values within the filter window equally and calculates the pixel values of the output picture.

boxm,n=1mn[11⋯111⋯1⋮⋮⋱⋮11⋯1]\begin{aligned}box_{m,n}=\frac{1}{mn}\begin{bmatrix}1 & 1 & \cdots & 1\\1 & 1 & \cdots & 1\\\vdots & \vdots & \ddots & \vdots\\1 & 1 & \cdots & 1\\\end{bmatrix}\end{aligned}

mm and nn are the filter kernel sizes.

API Interface

int32_t hbVPBoxFilter(hbUCPTaskHandle_t *taskHandle, hbVPImage *dstImg, hbVPImage const *srcImg, hbVPBoxFilterParam const *boxParam);

For detailed interface information, please refer to hbVPBoxFilter.

Usage

// Include the header #include "hobot/hb_ucp.h" #include "hobot/vp/hb_vp.h" #include "hobot/vp/hb_vp_box_filter.h" // init Image, allocate memory for image data hbUCPSysMem src_mem; hbUCPMallocCached(&src_mem, src_stride * src_height, 0); hbVPImage src_img{HB_VP_IMAGE_FORMAT_Y, HB_VP_IMAGE_TYPE_U8C1, src_width, src_height, src_stride, src_mem.virAddr, src_mem.phyAddr, nullptr, 0, 0}; hbUCPSysMem dst_mem; hbUCPMallocCached(&dst_mem, dst_stride * dst_height, 0); hbVPImage dst_img{HB_VP_IMAGE_FORMAT_Y, HB_VP_IMAGE_TYPE_U8C1, dst_width, dst_height, dst_stride, dst_mem.virAddr, dst_mem.phyAddr, nullptr, 0, 0}; // init param hbVPBoxFilterParam box_filter_param; box_filter_param.kernelHeight = 3; box_filter_param.kernelWidth = 3; box_filter_param.pointLocX = -1; box_filter_param.pointLocY = -1; box_filter_param.normalize = 1; box_filter_param.borderType = 0; // init task handle and schedule param hbUCPTaskHandle_t task_handle{nullptr}; hbUCPSchedParam sched_param; HB_UCP_INITIALIZE_SCHED_PARAM(&sched_param); sched_param.backend = HB_UCP_DSP_CORE_0; // create task hbVPBoxFilter(&task_handle, &dst_img, &src_img, &box_filter_param); // submit task hbUCPSubmitTask(task_handle, &sched_param); // wait for task done hbUCPWaitTaskDone(task_handle, 0); // release task handle hbUCPReleaseTask(task_handle); // release memory hbUCPFree(&src_mem); hbUCPFree(&dst_mem);