PUBLISHED 13 Jun 2016

Tizen offers various image processing features.

The main features of the Image Util API include:

Conversion
You can change the image and media packet color space among the supported formats.
Resizing
You can change the image and media packet resolution.
Rotation
You can change the image and media packet angle around the X or Y axis.
Crop
You can crop the outer parts of the image and media packet.
Decoding from a file or memory and encoding to a file or memory
You can decode images and encode them with the following formats:
- Bitmap formats: YUV420, YUV422, RGB888, RGBA8888, BGRA8888, and ARGB8888
- Input image formats for decoding: JPEG, PNG, GIF, and BMP
- Output image formats for encoding: JPEG, PNG, GIF, BMP, and animated GIF
  NotePay attention to how the image quality depends on the size and compression ratio.

Prerequisites

To enable your application to use the image util functionality:

To use the functions and data types of the Image Util API (in mobile and wearable applications), include the <image_util.h> header file in your application:
```
#include <image_util.h>
```
To ensure that an Image Util function has been executed properly, make sure that the return value is equal to IMAGE_UTIL_ERROR_NONE.

Declare the required variables:

#define SAMPLE_FILENAME "sample_image.jpg"
#define OUTPUT_ROTATED_JPEG "rotated_image.jpg"

const image_util_colorspace_e colorspace = IMAGE_UTIL_COLORSPACE_RGBA8888;
image_util_image_h src_image = NULL;
image_util_image_h dst_image = NULL;
image_util_decode_h decode_h = NULL;

To find out the color spaces supported on the device, use image_util_foreach_supported_colorspace():
```
int image_util_foreach_supported_colorspace(image_util_type_e image_type,
                                            image_util_supported_colorspace_cb callback, void *user_data);
```
The possible color spaces are defined in the image_util_colorspace_e enumeration (in mobile and wearable applications).

For more information on the YUV color space, see http://www.fourcc.org/yuv.php.

To support image_util_transform_run(), which is used for all image transformations, set the source image and create a handle for it (to be used as the second parameter):

ret = image_util_decode_create(&decode_h);
ret = image_util_decode_set_input_path(decode_h, SAMPLE_FILENAME);
ret = image_util_decode_set_colorspace(decode_h, colorspace);

ret = image_util_decode_run2(decode_h, &src_image);
ret = image_util_decode_destroy(decode_h);

Converting Image Color Space

To convert one color space of an image to another:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the target color space using image_util_transform_set_colorspace():
```
ret = image_util_transform_set_colorspace(transform_h, colorspace);
```

Execute the transformation using image_util_transform_run2():

ret = image_util_transform_run2(transform_h, src_image, &dst_image);

Execute the transformation using image_util_transform_run2_async():
```
ret = image_util_transform_run2_async(transform_h, src_image,
                                     (image_util_transform_completed2_cb)completed_callback,
                                      user_data);
```
Noteimage_util_transform_run2() and image_util_transform_run2_async() only converts the color space. These functions do not change the image width, height, or any other image property. Due to these restrictions of the image processing library, not all color space combinations are supported for conversion.
Handle the transformation results in image_util_transform_completed2_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Converting Media Packet Color Space

To convert one color space of a media packet to another:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the target color space using image_util_transform_set_colorspace():
```
ret = image_util_transform_set_colorspace(transform_h, colorspace);
```
Execute the transformation using image_util_transform_run():
```
ret = image_util_transform_run(transform_h, (media_packet_h)src_packet,
                              (image_util_transform_completed_cb)completed_callback,
                               user_data);
```
Noteimage_util_transform_run() only converts the color space. The function does not change the image width, height, or any other image property. Due to these restrictions of the image processing library, not all color space combinations are supported for conversion.
For more information on how to use the media packet handle of the Media Tool API, see Media Handle Management.
Handle the transformation results in image_util_transform_completed_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Resizing Image

To resize an image:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the target resolution using image_util_transform_set_resolution():

ret = image_util_transform_set_resolution(transform_h, width, height);

Run the transformation using image_util_transform_run2() or image_util_transform_run2_async():
```
ret = image_util_transform_run2(transform_h, src_image, &dst_image);
```
Note The image format has no effect on the transformation. If the color space is YUV, then the width and height of the target image must be multiples of eight. This restriction does not apply to the RGB images.
If image_util_transform_run2_async() is used to run the transformation, handle the transformation results in image_util_transform_completed2_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Resizing Media Packet

To resize a media packet:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the target resolution using image_util_transform_set_resolution():

ret = image_util_transform_set_resolution(transform_h, width, height);

Run the transformation using image_util_transform_run():
```
ret = image_util_transform_run(transform_h, (media_packet_h)src_packet,
                              (image_util_transform_completed_cb)completed_callback,
                               user_data);
```
NoteThe image format has no effect on the transformation. If the color space is YUV, then the width and height of the target image must be multiples of eight. This restriction does not apply to the RGB images.
Handle the transformation results in image_util_transform_completed_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(handle);
```

Rotating Image

To rotate an image:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the amount of rotation using image_util_transform_set_rotation():
```
ret = image_util_transform_set_rotation(transform_h, rotation);
```
The possible values for the rotation parameter are defined in the image_util_rotation_e enumeration (in mobile and wearable applications).
Execute the transformation using image_util_transform_run2() or image_util_transform_run2_async():
```
ret = image_util_transform_run2(transform_h, src_image, &dst_image);
```
Note The image format has no effect on the transformation. If the color space is YUV, then the width and height of the target image must be multiples of eight. This restriction does not apply to the RGB images.
Handle the transformation results in image_util_transform_completed2_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Rotating Media Packet

To rotate a media packet:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the amount of rotation using image_util_transform_set_rotation():
```
ret = image_util_transform_set_rotation(transform_h, rotation);
```
The possible values for the rotation parameter are defined in the image_util_rotation_e enumeration (in mobile and wearable applications).
Execute the transformation using image_util_transform_run():
```
ret = image_util_transform_run(transform_h, (media_packet_h)src_packet,
                              (image_util_transform_completed_cb)completed_callback,
                               user_data);
```
NoteThe image format has no effect on the transformation. If the color space is YUV, then the width and height of the target image must be multiples of eight. This restriction does not apply to the RGB images.
Handle the transformation results in image_util_transform_completed_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Cropping Image

To crop an image:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the crop area using image_util_transform_set_crop_area():

ret = image_util_transform_set_crop_area(transform_h, start_x, start_y, end_x, end_y);

Execute the transformation using image_util_transform_run2() or image_util_transform_run2_async():
```
ret = image_util_transform_run2_async(transform_h, src_image,
                                     (image_util_transform_completed2_cb)completed_callback,
                                      user_data);
```
Note As there is a YUV restriction and the crop start position can be set arbitrarily, the cropped image width and height must be even.
Handle the transformation results in image_util_transform_completed2_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Cropping Media Packet

To crop a media packet:

Create a transformation handle using image_util_transform_create():

transformation_h transform_h;
ret = image_util_transform_create(&transform_h);

Set the crop area using image_util_transform_set_crop_area():

ret = image_util_transform_set_crop_area(transform_h, start_x, start_y, end_x, end_y);

Execute the transformation using image_util_transform_run():

ret = image_util_transform_run(transform_h, (media_packet_h)src_packet,
                              (image_util_transform_completed_cb)completed_callback,
                               user_data);

Note As there is a YUV restriction and the crop start position can be set arbitrarily, the cropped image width and height must be even.

Handle the transformation results in image_util_transform_completed_cb(), which is invoked after the transformation is complete.
After the transformation is complete, destroy the transformation handle using image_util_transform_destroy():
```
ret = image_util_transform_destroy(transform_h);
```

Decoding from a File or Memory

To decode a JPEG, PNG, GIF, or BMP image:

Create a decoding handle using image_util_decode_create():

image_util_decode_h decode_h = NULL;
ret = image_util_decode_create(&decode_h);

Set the image to the input path or buffer using image_util_decode_set_input_path() or image_util_decode_set_input_buffer():
```
ret = image_util_decode_set_input_path(decode_h, path);
```
Additionally, you can set the color space and JPEG downscale using image_util_decode_set_colorspace() and image_util_decode_set_jpeg_downscale():
```
unsigned char *result = NULL;
ret = image_util_decode_set_colorspace(decode_h, IMAGE_UTIL_COLORSPACE_RGBA8888);
ret = image_util_decode_set_jpeg_downscale(decode_h, IMAGE_UTIL_DOWNSCALE_1_1);
```
Note
- Due to the decoder limitations, the color space setting is only supported for decoding the JPEG images. The default color space is IMAGE_UTIL_COLORSPACE_RGBA8888. PNG, GIF, and BMP images are decoded with IMAGE_UTIL_COLORSPACE_RGBA8888.

Execute the decoding using image_util_decode_run2() or image_util_decode_run_async2():

image_util_image_h decoded_image = NULL;
ret = image_util_decode_run2(decode_h, &decoded_image);

After the decoding is complete, destroy the decoding handle using image_util_decode_destroy():
```
ret = image_util_decode_destroy(decode_h);
```

Encoding to a File or Memory

To encode a raw image:

Create an encoding handle using image_util_encode_create():

image_util_type_e encoder_type = IMAGE_UTIL_JPEG;
image_util_encode_h encode_h = NULL;
ret = image_util_encode_create(encoder_type, &encode_h);

Additionally, you can set the JPEG quality or PNG compression using image_util_encode_set_quality() or image_util_encode_set_png_compression():
```
ret = image_util_encode_set_quality(decode_h, 100);
```
Note The compression is only supported for the PNG images. The default JPEG quality is 75. The default PNG compression is IMAGE_UTIL_PNG_COMPRESSION_6.
Execute the encoding using image_util_encode_run_to_file() or image_util_encode_run_to_buffer():
```
ret = image_util_encode_run_to_file(encode_h, decoded_image, file);
```
Note Due to the encoder limitations, the color space setting is only supported for encoding the JPEG images. The default color space is IMAGE_UTIL_COLORSPACE_RGBA8888. PNG, GIF, and BMP images are encoded with IMAGE_UTIL_COLORSPACE_RGBA8888.
After the encoding is complete, destroy the encoding handle using image_util_encode_destroy():
```
ret = image_util_encode_destroy(encode_h);
```

Encoding an Animated GIF

To encode an animated GIF image:

Create an encoding handle using image_util_agif_encode_create():

image_util_agif_encode_h agif_encode_h = NULL;
ret = image_util_agif_encode_create(&agif_encode_h);

Add the images with the delay time between GIF frames using image_util_agif_encode_add_frame():
```
ret = image_util_agif_encode_add_frame(agif_encode_h, src_image, delay_time);
```
Save the encoded image using image_util_agif_encode_save_to_file() or image_util_agif_encode_save_to_buffer():
```
ret = image_util_agif_encode_save_to_file(agif_encode_h, path);
```
After the encoding is complete, destroy the encoding handle using image_util_agif_encode_destroy():
```
ret = image_util_agif_encode_destroy(agif_encode_h);
```

Supported Color Space Formats

The following tables define the supported color space formats.

Table: RGB pixel formats

Label	FOURCC in hex	Bits per pixel	Description
RGB	0x32424752	1, 4, 8, 16, 24, 32	Alias for BI_RGB
RGBA	0x41424752	16, 32	Raw RGB with alpha. Sample precision and packing is arbitrary and determined using bit masks for each component, as for BI_BITFIELDS.

Table: Packed YUV formats

Label	FOURCC in hex	Bits per pixel	Description
UYVY	0x59565955	16	YUV 4:2:2 (Y sample at every pixel, U and V sampled at every second pixel horizontally on each line). A macropixel contains 2 pixels in 1 u_int32.
YUYV	0x56595559	16	Duplicate of YUY2.

Table: Planar YUV formats

Label	FOURCC in hex	Bits per pixel	Description
YV16	0x36315659	16	8-bit Y plane followed by 8-bit 2×1 subsampled V and U planes.
YV12	0x32315659	12	8-bit Y plane followed by 8-bit 2×2 subsampled V and U planes.
I420	0x30323449	12	8-bit Y plane followed by 8-bit 2×2 subsampled U and V planes.
NV12	0x3231564E	12	8-bit Y plane followed by an interleaved U/V plane with 2×2 subsampling.
NV21	0x3132564E	12	As NV12 with U and V reversed in the interleaved plane.

Quality and Size Comparison

The following table shows the effect on the image quality and file sizes when using different compression ratios.

Table: Quality and size comparison

Quality	Size (bytes)	Compression ratio	Description
Highest quality (Q = 100)	83,261	2.6:1	Extremely minor artifacts
High quality (Q = 50)	15,138	15:1	Initial signs of subimage artifacts
Medium quality (Q = 25)	9,553	23:1	Stronger artifacts; loss of high-frequency information
Low quality (Q = 10)	4,787	46:1	Severe high frequency loss; artifacts on subimage boundaries (“macroblocking”) are obvious
Lowest quality	–	–	–

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Tizen Developers

Image Editing

Prerequisites

Converting Image Color Space

Converting Media Packet Color Space

Resizing Image

Resizing Media Packet

Rotating Image

Rotating Media Packet

Cropping Image

Cropping Media Packet

Decoding from a File or Memory

Encoding to a File or Memory

Encoding an Animated GIF

Supported Color Space Formats

Quality and Size Comparison

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Image Editing

Prerequisites

Converting Image Color Space

Converting Media Packet Color Space

Resizing Image

Resizing Media Packet

Rotating Image

Rotating Media Packet

Cropping Image

Cropping Media Packet

Decoding from a File or Memory

Encoding to a File or Memory

Encoding an Animated GIF

Supported Color Space Formats

Quality and Size Comparison