Image Creation and Conversion

Table of Contents

• Creating an Image
  • Basic Creation
  • Creation with Provided Buffer
• Accessing Data Explicitly
• Converting Format

This section demonstrates the different methods to create an Image.

Once an image is created, you can stream it from host (CPU) memory to device (CUDA) memory across:

• A single process and thread.
• Multiple processes.
• Multiple threads.

Creating an Image

Basic Creation

This is the simplest method to create an image.
The ownership for the image is transferred to the application, which is responsible for destroying the object when no longer needed.

dwImageProperties imageProperties{};
imageProperties.type = DW_IMAGE_CPU;
imageProperties.format = DW_IMAGE_FORMAT_RGB_UINT8_PLANAR;
imageProperties.width = 1200;
imageProperties.height = 800;
dwImageHandle_t image;
dwImage_create(&image, imageProperties, ...);
 
// CODE: Use image
dwSomeDriveWorksModule_compute(image,...);
 
dwImage_destroy(&image);

Creation with Provided Buffer

This method is similar to the Basic Creation. In this case, the application provides the memory buffer used to store the image.

uint8_t* buffer[3];
// CODE: Read some data source into buffer
size_t* pitch[3];
// CODE: Calculate pitch
 
dwImageProperties imageProperties{};
imageProperties.type = DW_IMAGE_CPU;
imageProperties.format = DW_IMAGE_FORMAT_RGB_UINT8_PLANAR;
imageProperties.width = 1200;
imageProperties.height = 800;
 
dwImageHandle_t image;
dwImage_createAndBindBuffer(&image, imageProperties, buffer, pitch, ...);
 
// CODE: Use image
dwSomeDriveWorksModule_compute(image,...); // NOTE, buffer might be modified here
 
// Destroy the image handle
dwImage_destroy(&image);
 
// Note, the user provided buffer is still available for usage

Accessing Data Explicitly

After creating an image through the demonstrated methods above, its content can be accessed in the following way:

dwImageCPU *imageCPU;
dwImage_getCPU(&imageCPU, image);
 
size_t planeCount;
dwImage_getPlaneCount(&planeCount, DW_IMAGE_FORMAT_RGB_UINT8_PLANAR);
 
for (uint32_t plane = 0; plane < planeCount; ++p) {
    for (uint32_t i = 0; i < imageProperties.height; ++i) {
        for (uint32_t j = 0; j < imageProperties.width; ++j) {
            imageCPU->data[plane][i * imageCPU->pitch[plane] + j] = ...; // this affects the image
        }
    }
}

Note

This snippet assumes the type of the image created is DW_IMAGE_CPU.

Converting Format

An image's format and properties can be converted in the following way:

dwImageProperties imageProperties{};
imageProperties.type = DW_IMAGE_CUDA;
imageProperties.format = DW_IMAGE_FORMAT_RGBA_UINT8;
imageProperties.width = 1200;
imageProperties.height = 800;
dwImageHandle_t outputImage;
dwImage_create(&outputImage, imageProperties, ...);
 
// CODE: Get some CUDA image
dwImageHandle_t inputImage
dwSomeDriveWorksModule_getImage(inputImage,...);
 
dwImage_copyConvert(outputImage, inputImage,...);
 
// CODE: Use outputImage
...
 
// Destroy the outputing image 
dwImage_destroy(&outputImage);

Note

The input and output images must be of the same type.

This operation applies to DW_IMAGE_CUDA and DW_IMAGE_NVMEDIA only.