Cvtcolor
The operator converts the input picture from one color space to another,
supporting the conversion of color channels, formats and depths, often
to convert the picture format.
Operator Effect
| Input Image | Parameter | Output Image |
|---|
 | - |  |
Principle
There are a variety of formulas to choose from for the color space conversion process, and one method is listed as belows:
RGB to Gray
Y=0.299∗R+0.587∗G+0.114∗B
RGB/BGR ⇔ YUV420
Y=16+0.257∗R+0.504∗G+0.098∗B
Cb=128−0.148∗R−0.291∗G+0.439∗B
Cr=128+0.439∗R−0.368∗G−0.071∗B
R=1.164∗(Y−16)+1.596∗(Cr−128)
G=1.164∗(Y−16)−0.392∗(Cb−128)−0.812∗(Cr−128)
B=1.164∗(Y−16)+2.016∗(Cb−128)
API Interface
int32_t hbVPCvtColor(hbUCPTaskHandle_t *taskHandle,
hbVPImage *dstImg,
hbVPImage const *srcImg);
For detailed interface information, please refer to hbVPCvtColor.
Usage
// Include the header
#include "hobot/hb_ucp.h"
#include "hobot/vp/hb_vp.h"
#include "hobot/vp/hb_vp_cvt_color.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_RGB,
HB_VP_IMAGE_TYPE_U8C3,
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 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
hbVPCvtColor(&task_handle, &dst_img, &src_img);
// 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);
