The APIs under this category are used to initialize the decoding parameters as part of the :code:`nvtiffDecodeParams_t` handle.
Once initialized, the handle can be passed as an input to :ref:`nvtiffdecodeimage-label`


.. _nvtiffdecodeparamssetoutputformat-label:

nvtiffDecodeParamsSetOutputFormat()
""""""""""""""""""""""""""""""""""""
Used to set the decode output format. See :ref:`nvtiffdecodeoutputformat-label` for details. The default value is :code:`NVTIFF_OUTPUT_UNCHANGED_I`. 

.. note:: When the photometric interpretation is :code:`NVTIFF_PHOTOMETRIC_YCBCR` and compression is :code:`NVTIFF_COMPRESSION_JPEG`, output format must be set to either :code:`NVTIFF_OUTPUT_RGB_I_UINT8` or :code:`NVTIFF_OUTPUT_RGB_I_UINT16`.

.. note:: When the photometric interpretation is :code:`NVTIFF_PHOTOMETRIC_MASK`, only :code:`NVTIFF_OUTPUT_UNCHANGED_I` can be used.


When setting the output format to :code:`NVTIFF_OUTPUT_UNCHANGED_I`-

the size in bytes of the decode output buffer when bits_per_pixel is a multiple 8, should be
:code:`image_width * image_height * (bits_per_pixel/8)`

the size in bytes of the decode output buffer when bits_per_pixel is less than  8, should be
:code:`(image_width * bits_per_pixel + 7)/8  * image_height`


When setting the output to :code:`NVTIFF_OUTPUT_RGB_I_UINT8`-

the size in bytes of the decode output buffer should be
:code:`image_width * image_height * 3 * sizeof(uint8_t)`

When setting the output to :code:`NVTIFF_OUTPUT_RGB_I_UINT16`-

the size in bytes of the decode output buffer should be 
:code:`image_width * image_height * 3 * sizeof(uint16_t)`


**Signature:**

.. code-block:: cpp

    nvtiffStatus_t nvtiffDecodeParamsSetOutputFormat(nvtiffDecodeParams_t decode_params, 
        nvtiffOutputFormat_t format);

**Parameters:**

.. list-table::
  :header-rows: 1
  :widths: 15 10 10 20

  * - Parameter
    - Input/Output
    - Memory
    - Description
  * - nvtiffDecodeParams_t decode_params
    - Input/Output
    - Host
    - Decode output parameters handle.
  * - nvtiffOutputFormat_t format
    - Input
    - Host
    - Output format value. Defaults to :code:`NVTIFF_OUTPUT_UNCHANGED_I`.


**Returns:**

:code:`nvtiffStatus_t` - An error code as specified in :ref:`nvtiffapireturncodesv2-label`



nvtiffDecodeParamsSetROI()
"""""""""""""""""""""""""""
Used to set the region of interest for decoding. The entire image is decoded by default.

    • offset_x and offset_y should be greater than or equal to 0, and cannot exceed image width and height respectively. 
    • offset_x + roi_width and  offset_y + roi_height cannot exceed image width and image height respectively.
    • When image bitdepth is 1, offset_x and roi_width should be a multiple of 8

**Signature:**

.. code-block:: cpp

    nvjpeg2kStatus_t nvtiffDecodeParamsSetROI(nvtiffDecodeParams_t decode_params,
            int32_t offset_x,
            int32_t offset_y,
            int32_t roi_width,
            int32_t roi_height)

**Parameters:**

.. list-table::
  :header-rows: 1
  :widths: 15 10 10 20

  * - Parameter
    - Input/Output
    - Memory
    - Description
  * - nvtiffDecodeParams_t decode_params
    - Input/Output
    - Host
    - Decode output parameter handle
  * - int32_t offset_x
    - Input
    - Host
    - Image offset along the horizontal direction relative to the top left corner.
  * - int32_t offset_y
    - Input
    - Host
    - Image offset along the vertical direction relative to the top left corner.
  * - int32_t roi_width
    - Input
    - Host
    - Image width relative to offset_x
  * - int32_t roi_height
    - Input
    - Host
    - Image height relative to offset_y


**Returns:**

:code:`nvtiffStatus_t` - An error code as specified in :ref:`nvtiffapireturncodesv2-label`