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  • 3.0.31

    • 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 ImageParameterOutput Image
    VP5input_rgb-VP5out_cvtcolor

    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∗BY=0.299*R+0.587*G+0.114*B

    RGB/BGR ⇔\Leftrightarrow YUV420

    Y=16+0.257∗R+0.504∗G+0.098∗BY=16+0.257*R+0.504*G+0.098*B

    Cb=128−0.148∗R−0.291∗G+0.439∗BCb=128-0.148*R-0.291*G+0.439*B

    Cr=128+0.439∗R−0.368∗G−0.071∗BCr=128+0.439*R-0.368*G-0.071*B

    R=1.164∗(Y−16)+1.596∗(Cr−128)R=1.164*(Y-16)+1.596*(Cr-128)

    G=1.164∗(Y−16)−0.392∗(Cb−128)−0.812∗(Cr−128)G=1.164*(Y-16)-0.392*(Cb-128)-0.812*(Cr-128)

    B=1.164∗(Y−16)+2.016∗(Cb−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);