imageprocessing/geometry/imagetransformation/docs/usecase1.md

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# Copyright (c) 2019-2020 NVIDIA CORPORATION.  All rights reserved.

@page imagetransformation_usecase1 Image Scaling
@tableofcontents

@note SW Release Applicability: This tutorial is applicable to modules in both **NVIDIA DriveWorks** and **NVIDIA DRIVE Software** releases.

This section explains how to utilize the ImageTransformation module to downscale an image's ROI.

@section imagetransformation_usecase1_creating Creating an Image

To create an image for where the output should be copied:

```{cpp}
dwImageProperties imgProperties{};
dwSensorCamera_getImageProperties(&imgProperties, DW_CAMERA_OUTPUT_NATIVE_PROCESSED, camera);

imgProperties.width /= 2;
imgProperties.height /= 2;

dwImageHandle_t imageSmall = DW_NULL_HANDLE;
dwImage_create(&imageSmall, imgProperties, m_context);
```

@section imagetransformation_usecase1_initializing Initializing the ImageTransformation Module

The ::dwImageTransformationHandle_t handle initializes the ImageTransformation module with the following parameters:

For a complete description of all parameters, please refer to ::dwImageTransformationParameters.

```{cpp}
dwImageTransformationHandle_t imageTransformationEngine = DW_NULL_HANDLE;
dwImageTransformationParameters params{};
params.ignoreAspectRatio = false;
dwImageTransformation_initialize(&imageTransformationEngine, params, context);

dwImageTransformation_setBorderMode(DW_IMAGEPROCESSING_BORDER_MODE_ZERO, imageTransformationEngine);
dwImageTransformation_setInterpolationMode(m_interpolation, imageTransformationEngine);
```

@section imagetransformation_usecase1_transforming Performing the Transformation

```{cpp}
dwImageTransformation_copyFullImage(imageSmall, imageInput, imageTransformationEngine);
```

@section imagetransformation_usecase1_releasing_handle Releasing the Handle

To release the handle:

```{.cpp}
    dwImageTransformation_release(imageTransformationEngine);
```

To see a full demonstration of this workflow, please refer to @ref dwx_imagetransformation.