佳能EDSDK如何获得实时视图图像的宽度和高度

Question

我编写了c++代码在监视器上显示实时视图图像。我在stackoverflow上引用了一些代码。最后，我完成了我的代码，但是有一些问题。

我想使用opencv显示实时视图图像，但我不知道如何获得宽度&实时图像的高度。(可能是EDSDK函数检索…)

请回答我。

(我附上了我的代码，我想要合适的回答我的代码)

(看"//libjpegTurbo…//，有手动_width &高度。我想检索使用函数)

---

// Functions_body
bool LiveViewStart() 
{
    EdsError err = EDS_ERR_OK;
    EdsCameraListRef cameraList = NULL;
    EdsCameraRef camera = NULL;
    EdsUInt32    count = 0; 
    bool         isSDKLoaded = false;
    // Initialize SDK
    err = EdsInitializeSDK(); 
    if(err == EDS_ERR_OK) 
    { 
        isSDKLoaded = true; 
    }
    // Acquisition of camera list
    if(err == EDS_ERR_OK)
    {
        err = EdsGetCameraList(&cameraList);
    }
    // Acquisition of number of Cameras
    if(err == EDS_ERR_OK)
    {
        err = EdsGetChildCount(cameraList, &count);
        if(count == 0)
        {
            err = EDS_ERR_DEVICE_NOT_FOUND;
        }
    }
    // Acquisition of camera at the head of the list
    if(err == EDS_ERR_OK)
    {   
        err = EdsGetChildAtIndex(cameraList , 0 , &camera); 
    }
    // Acquisition of camera information
    EdsDeviceInfo deviceInfo;
    if(err == EDS_ERR_OK)
    {   
        err = EdsGetDeviceInfo(camera , &deviceInfo);   
        if(err == EDS_ERR_OK && camera == NULL)
        {
            err = EDS_ERR_DEVICE_NOT_FOUND;
        }
    }
    // Release camera list
    if(cameraList != NULL)
    {
        EdsRelease(cameraList);
    }
    if(err != EDS_ERR_OK)
    {
        ::MessageBox(NULL,"Cannot detect camera",NULL,MB_OK);
        exit(1);
    }
    // Open session with camera 
    if(err == EDS_ERR_OK) 
    { 
        err = EdsOpenSession(camera); 
    } 
    // Start Live view  
    // Get the output device for the live view image
    EdsUInt32 device;
    err = EdsGetPropertyData(camera, kEdsPropID_Evf_OutputDevice, 0, sizeof(device), &device);
    // PC live view starts by setting the PC as the output device for the live view image. 
    if(err == EDS_ERR_OK) 
    { 
        device |= kEdsEvfOutputDevice_PC; 
        err = EdsSetPropertyData(camera, kEdsPropID_Evf_OutputDevice, 0 , sizeof(device), &device);
    } 
    Sleep(2000);
    // Download EvfData
    EdsEvfImageRef evfImage = NULL;
    EdsStreamRef stream = NULL;
    unsigned char* data = NULL;
    unsigned long size = 0;
    // Create memory stream
    err = EdsCreateMemoryStream(0, &stream);
    if (err != EDS_ERR_OK) {
        cout << "Download Live View Image Error in Function EdsCreateMemoryStream: " << err << "n";
        return false;
    }
    // Create EvfImageRef.
    err = EdsCreateEvfImageRef(stream, &evfImage);
    if (err != EDS_ERR_OK) {
        cout << "Download Live View Image Error in Function EdsCreateEvfImageRef: " << err << "n";
        return false;
    }
    // Download live view image data.
    err = EdsDownloadEvfImage(camera, evfImage);
    if (err != EDS_ERR_OK) {
        cout << "Download Live View Image Error in Function EdsDownloadEvfImage: " << err << "n";
        return false;
    }
    //Sleep(1000);
    // Get Pointer of evfStream
    err = EdsGetPointer(stream, (EdsVoid**)& data);
    if (err != EDS_ERR_OK) {
        cout << "Download Live View Image Error in Function EdsGetPointer: " << err << "n";
        return false;
    }
    // Get Length of evfStream
    err = EdsGetLength(stream, &size);
    if (err != EDS_ERR_OK) {
        cout << "Download Live View Image Error in Function EdsGetLength: " << err << "n";
        return false;
    }

    // libjpegTurbo(data, size);
    int JPEG_QUALITY = 75;
    int COLOR_COMPONENTS = 3;
    int _width = 1920;
    int _height = 1080;
    long unsigned int _jpegSize = 0;
    unsigned char *_compressedImage = NULL;
    unsigned char *buffer = new unsigned char [_width * _height * COLOR_COMPONENTS];
    tjhandle _jpegCompressor = tjInitCompress();
    tjCompress2(_jpegCompressor, buffer, _width, 0, _height, TJPF_RGB, &_compressedImage, &_jpegSize, TJSAMP_444, JPEG_QUALITY, TJFLAG_FASTDCT);
    tjDestroy(_jpegCompressor);
    // display RGB image in opencv
    // Release stream
    if (stream != NULL) {
        EdsRelease(stream);
        stream = NULL;
    }
    // Release evfImage
    if (evfImage != NULL) {            
        EdsRelease(evfImage);
        evfImage = NULL;
    }
    data = NULL;
    // End Live view.
    // Get the output device for the live view image
    err = EdsGetPropertyData(camera, kEdsPropID_Evf_OutputDevice, 0, sizeof(device), &device);
    // PC live view ends if the PC is disconneccted from the live view output device.
    if(err == EDS_ERR_OK)
    {
        device &= ~kEdsEvfOutputDevice_PC;
        err = EdsSetPropertyData(camera, kEdsPropID_Evf_OutputDevice, 0, sizeof(device), &device);
    }
    // Close session with camera 
    if(err == EDS_ERR_OK) 
    {
        err = EdsCloseSession(camera); 
    } 
    // Release camera 
    if(camera != NULL) 
    { 
        EdsRelease(camera); 
    } 
    // Terminate SDK 
    if(isSDKLoaded) 
    { 
        EdsTerminateSDK(); 
    } 
    return true;
} 

Answer 1

佳能SDK不提供任何函数来获取实时视图图像的大小。你在代码中面临的问题是，你试图压缩图像，但你需要解压。我建议你仔细阅读一下libjpg turbo的用法。他们提供了很好的文档示例:http://www.libjpeg-turbo.org/Documentation/Documentation

旁注:这是你真正的代码还是只是为了展示?因为实时图像下载必须在循环中反复调用，否则您将只下载一个图像并关闭所有内容。

亲切的问候

Answer 2

如果你有一个evfImage，你可以使用EdsGetPropertyData请求它的kedspropid_evf_coordinatessystem(类型EdsSize)。