vx_tutorial_image_extract_channel.c File Reference

#include <stdio.h>
#include <VX/vx.h>
#include <VX/vxu.h>
#include <utility.h>

Go to the source code of this file.

Macros
#define	IN_FILE_NAME   "${VX_TEST_DATA_PATH}/colors.bmp"
	Input file name.
#define	OUT_FILE_NAME   "${VX_TEST_DATA_PATH}/vx_tutorial_image_extract_channel_out.bmp"
	Output file name.

Functions
void	vx_tutorial_image_extract_channel ()
	Tutorial Entry Point. More...

Detailed Description

Extract channels from RGB image using immediate mode then combine them in opposite order.

In this tutorial we learn the below concepts,

• How to create OpenVX context and OpenVX image data object
• How to read a BMP file and load the pixel values into the image data object
• How to query the image data object for attributes like width, height
• How to use the immediate mode for image processing
• How to read pixel values from an image data object and save it as a BMP file
• How to cleanup all created resources and exit the OpenVX application

To include OpenVX interfaces include below file

#include <VX/vx.h>

To include OpenVX interfaces for immediate mode include below file

#include <VX/vxu.h>

Follow the comments in the function vx_tutorial_image_extract_channel() to understand this tutorial

Definition in file vx_tutorial_image_extract_channel.c.

Function Documentation

vx_tutorial_image_extract_channel()

void vx_tutorial_image_extract_channel

(

)

Tutorial Entry Point.

- Define objects that we wish to create in the OpenVX application.

A vx_context object is defined which is used as input parameter for all subesquent OpenVX object create APIs

  /
vx_context context;
vx_image in_image = NULL;
vx_image r_channel = NULL;
vx_image g_channel = NULL;
vx_image b_channel = NULL;
vx_image out_image = NULL;

- Create OpenVX context.

This MUST be done first before any OpenVX API call. The context that is returned is used as input for subsequent OpenVX APIs

  /
context = vxCreateContext();

- Create image object.

Follow the comments in tivx_utils_create_vximage_from_bmpfile() to see how a vx_image object is created and filled with RGB data from BMP file IN_FILE_NAME

  /
in_image = tivx_utils_create_vximage_from_bmpfile(context, IN_FILE_NAME, (vx_bool)vx_false_e);

- Show image attributes.

Follow the comments in show_image_attributes() to see how image attributes are queried and displayed.

  /
show_image_attributes(in_image);

- Create OpenVX image object.

Creates an OpenVX image object of 'width' x 'height' and having data format 'df'.

  /
r_channel = vxCreateImage(context, width, height, (vx_df_image)VX_DF_IMAGE_U8);

- Show image attributes.

Follow the comments in show_image_attributes() to see how image attributes are queried and displayed.

  /
show_image_attributes(r_channel);

- Create OpenVX image object.

Creates an OpenVX image object of 'width' x 'height' and having data format 'df'.

  /
g_channel = vxCreateImage(context, width, height, (vx_df_image)VX_DF_IMAGE_U8);

- Create OpenVX image object.

Creates an OpenVX image object of 'width' x 'height' and having data format 'df'.

  /
b_channel = vxCreateImage(context, width, height, (vx_df_image)VX_DF_IMAGE_U8);

- Show image attributes.

Follow the comments in show_image_attributes() to see how image attributes are queried and displayed.

  /
show_image_attributes(b_channel);

- Create OpenVX image object.

Creates an OpenVX image object of 'width' x 'height' and having data format 'df'.

  /
out_image = vxCreateImage(context, width, height, (vx_df_image)VX_DF_IMAGE_RGB);

- Show image attributes.

Follow the comments in show_image_attributes() to see how image attributes are queried and displayed.

  /
show_image_attributes(out_image);

- Performs immediate mode channel extract.

The second argument gives the input image, the third argument gives the channel to extract and the final argument gives the output image.

  /
vxuChannelExtract(context, in_image, (vx_enum)VX_CHANNEL_R, r_channel);
vxuChannelExtract(context, in_image, (vx_enum)VX_CHANNEL_G, g_channel);
vxuChannelExtract(context, in_image, (vx_enum)VX_CHANNEL_B, b_channel);

- Performs immediate mode channel combine.

The second, third and fourth arguments give channels to combine with the last argument being the output image.

  /
vxuChannelCombine(context, b_channel, g_channel, r_channel, NULL, out_image);

- Save image object to bitmap file OUT_FILE_NAME.

Follow the comments in tivx_utils_save_vximage_to_bmpfile() to see how data in vx_image object is accessed to store pixel values from the image object to BMP file OUT_FILE_NAME

  /
tivx_utils_save_vximage_to_bmpfile(OUT_FILE_NAME, out_image);

- Release image object.

Since we are done with using this image object, release it

  /
vxReleaseImage(&in_image);
vxReleaseImage(&r_channel);
vxReleaseImage(&g_channel);
vxReleaseImage(&b_channel);
vxReleaseImage(&out_image);

- Release context object.

Since we are done using OpenVX context, release it. No further OpenVX API calls should be done, until a context is again created using vxCreateContext()

  /
vxReleaseContext(&context);

Definition at line 108 of file vx_tutorial_image_extract_channel.c.