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image.h File Reference

Image helper functions like resizing, color filter, converters... More...

#include "std.h"
#include <sys/time.h>
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Go to the source code of this file.

Data Structures

struct  image_t
 
struct  point_t
 
struct  flow_t
 

Enumerations

enum  image_type { IMAGE_YUV422, IMAGE_GRAYSCALE, IMAGE_JPEG, IMAGE_GRADIENT }
 

Functions

void image_create (struct image_t *img, uint16_t width, uint16_t height, enum image_type type)
 Create a new image. More...
 
void image_free (struct image_t *img)
 Free the image. More...
 
void image_copy (struct image_t *input, struct image_t *output)
 Copy an image from inut to output This will only work if the formats are the same. More...
 
void image_switch (struct image_t *a, struct image_t *b)
 This will switch image *a and *b This is faster as image_copy because it doesn't copy the whole image buffer. More...
 
void image_to_grayscale (struct image_t *input, struct image_t *output)
 Convert an image to grayscale. More...
 
uint16_t image_yuv422_colorfilt (struct image_t *input, struct image_t *output, uint8_t y_m, uint8_t y_M, uint8_t u_m, uint8_t u_M, uint8_t v_m, uint8_t v_M)
 Filter colors in an YUV422 image. More...
 
void image_yuv422_downsample (struct image_t *input, struct image_t *output, uint16_t downsample)
 Simplified high-speed low CPU downsample function without averaging downsample factor must be 1, 2, 4, 8 ... More...
 
void image_subpixel_window (struct image_t *input, struct image_t *output, struct point_t *center, uint16_t subpixel_factor)
 This outputs a subpixel window image in grayscale Currently only works with Grayscale images as input but could be upgraded to also support YUV422 images. More...
 
void image_gradients (struct image_t *input, struct image_t *dx, struct image_t *dy)
 Calculate the gradients using the following matrix: [0 -1 0; -1 0 1; 0 1 0]. More...
 
void image_calculate_g (struct image_t *dx, struct image_t *dy, int32_t *g)
 Calculate the G vector of an image gradient This is used for optical flow calculation. More...
 
uint32_t image_difference (struct image_t *img_a, struct image_t *img_b, struct image_t *diff)
 Calculate the difference between two images and return the error This will only work with grayscale images. More...
 
int32_t image_multiply (struct image_t *img_a, struct image_t *img_b, struct image_t *mult)
 Calculate the multiplication between two images and return the error This will only work with image gradients. More...
 
void image_show_points (struct image_t *img, struct point_t *points, uint16_t points_cnt)
 Show points in an image by coloring them through giving the pixels the maximum value. More...
 
void image_show_flow (struct image_t *img, struct flow_t *vectors, uint16_t points_cnt, uint8_t subpixel_factor)
 Shows the flow from a specific point to a new point This works on YUV422 and Grayscale images. More...
 
void image_draw_line (struct image_t *img, struct point_t *from, struct point_t *to)
 Draw a line on the image. More...
 

Detailed Description

Image helper functions like resizing, color filter, converters...

Definition in file image.h.


Data Structure Documentation

struct image_t

Definition at line 42 of file image.h.

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Data Fields
void * buf Image buffer (depending on the image_type)
uint8_t buf_idx Buffer index for V4L2 freeing.
uint32_t buf_size The buffer size.
uint16_t h Image height.
struct timeval ts The timestamp of creation.
enum image_type type The image type.
uint16_t w Image width.
struct point_t

Definition at line 54 of file image.h.

Data Fields
uint16_t x The x coordinate of the point.
uint16_t y The y coordinate of the point.
struct flow_t

Definition at line 60 of file image.h.

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Data Fields
int16_t flow_x The x direction flow in subpixels.
int16_t flow_y The y direction flow in subpixels.
struct point_t pos The original position the flow comes from.

Enumeration Type Documentation

enum image_type
Enumerator
IMAGE_YUV422 

UYVY format (uint16 per pixel)

IMAGE_GRAYSCALE 

Grayscale image with only the Y part (uint8 per pixel)

IMAGE_JPEG 

An JPEG encoded image (not per pixel encoded)

IMAGE_GRADIENT 

An image gradient (int16 per pixel)

Definition at line 34 of file image.h.

Function Documentation

void image_calculate_g ( struct image_t dx,
struct image_t dy,
int32_t g 
)

Calculate the G vector of an image gradient This is used for optical flow calculation.

Parameters
[in]*dxThe gradient in the X direction
[in]*dyThe gradient in the Y direction
[out]*gThe G[4] vector devided by 255 to keep in range

Definition at line 325 of file image.c.

References image_t::buf, image_t::h, and image_t::w.

Referenced by opticFlowLK().

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void image_copy ( struct image_t input,
struct image_t output 
)

Copy an image from inut to output This will only work if the formats are the same.

Parameters
[in]*inputThe input image to copy from
[out]*outputThe out image to copy to

Definition at line 77 of file image.c.

References image_t::buf, image_t::buf_size, image_t::h, image_t::ts, image_t::type, and image_t::w.

Referenced by opticflow_calc_frame().

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void image_create ( struct image_t img,
uint16_t  width,
uint16_t  height,
enum image_type  type 
)

Create a new image.

Parameters
[out]*imgThe output image
[in]widthThe width of the image
[in]heightThe height of the image
[in]typeThe type of image (YUV422 or grayscale)

Definition at line 38 of file image.c.

References image_t::buf, image_t::buf_size, image_t::h, IMAGE_GRADIENT, IMAGE_JPEG, IMAGE_YUV422, image_t::type, and image_t::w.

Referenced by bebop_front_camera_thread(), cv_blob_locator_func(), cv_window_func(), detect_window(), opticflow_calc_init(), opticflow_module_calc(), opticFlowLK(), qrscan(), video_thread_function(), video_thread_periodic(), and viewvideo_function().

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uint32_t image_difference ( struct image_t img_a,
struct image_t img_b,
struct image_t diff 
)

Calculate the difference between two images and return the error This will only work with grayscale images.

Parameters
[in]*img_aThe image to substract from
[in]*img_bThe image to substract from img_a
[out]*diffThe image difference (if not needed can be NULL)
Returns
The squared difference summed

Definition at line 357 of file image.c.

References image_t::buf, image_t::h, and image_t::w.

Referenced by opticFlowLK().

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void image_draw_line ( struct image_t img,
struct point_t from,
struct point_t to 
)

Draw a line on the image.

Parameters
[in,out]*imgThe image to show the line on
[in]*fromThe point to draw from
[in]*toThe point to draw to

Definition at line 479 of file image.c.

References image_t::buf, image_t::h, IMAGE_YUV422, image_t::type, image_t::w, point_t::x, and point_t::y.

Referenced by image_show_flow().

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void image_free ( struct image_t img)

Free the image.

Parameters
[in]*imgThe image to free

Definition at line 63 of file image.c.

References image_t::buf.

Referenced by cv_blob_locator_func(), cv_window_func(), detect_window(), opticflow_module_calc(), opticFlowLK(), video_thread_function(), video_thread_periodic(), and viewvideo_function().

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void image_gradients ( struct image_t input,
struct image_t dx,
struct image_t dy 
)

Calculate the gradients using the following matrix: [0 -1 0; -1 0 1; 0 1 0].

Parameters
[in]*inputInput grayscale image
[out]*dxOutput gradient in the X direction (dx->w = input->w-2, dx->h = input->h-2)
[out]*dyOutput gradient in the Y direction (dx->w = input->w-2, dx->h = input->h-2)

Definition at line 302 of file image.c.

References image_t::buf, image_t::h, and image_t::w.

Referenced by opticFlowLK().

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int32_t image_multiply ( struct image_t img_a,
struct image_t img_b,
struct image_t mult 
)

Calculate the multiplication between two images and return the error This will only work with image gradients.

Parameters
[in]*img_aThe image to multiply
[in]*img_bThe image to multiply with
[out]*multThe image multiplication (if not needed can be NULL)
Returns
The sum of the multiplcation

Definition at line 395 of file image.c.

References image_t::buf, image_t::h, and image_t::w.

Referenced by opticFlowLK().

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void image_show_flow ( struct image_t img,
struct flow_t vectors,
uint16_t  points_cnt,
uint8_t  subpixel_factor 
)

Shows the flow from a specific point to a new point This works on YUV422 and Grayscale images.

Parameters
[in,out]*imgThe image to show the flow on
[in]*vectorsThe flow vectors to show
[in]*points_cntThe amount of points and vectors to show

Definition at line 456 of file image.c.

References flow_t::flow_x, flow_t::flow_y, image_draw_line(), flow_t::pos, point_t::x, and point_t::y.

Referenced by opticflow_calc_frame().

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void image_show_points ( struct image_t img,
struct point_t points,
uint16_t  points_cnt 
)

Show points in an image by coloring them through giving the pixels the maximum value.

This works with YUV422 and grayscale images

Parameters
[in,out]*imgThe image to place the points on
[in]*pointsThe points to sohw
[in]*points_cntThe amount of points to show

Definition at line 431 of file image.c.

References image_t::buf, IMAGE_YUV422, image_t::type, image_t::w, point_t::x, and point_t::y.

Referenced by opticflow_calc_frame().

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void image_subpixel_window ( struct image_t input,
struct image_t output,
struct point_t center,
uint16_t  subpixel_factor 
)

This outputs a subpixel window image in grayscale Currently only works with Grayscale images as input but could be upgraded to also support YUV422 images.

Parameters
[in]*inputInput image (grayscale only)
[out]*outputWindow output (width and height is used to calculate the window size)
[in]*centerCenter point in subpixel coordinates
[in]subpixel_factorThe subpixel factor per pixel

Definition at line 247 of file image.c.

References image_t::buf, image_t::h, image_t::w, point_t::x, and point_t::y.

Referenced by opticFlowLK().

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void image_switch ( struct image_t a,
struct image_t b 
)

This will switch image *a and *b This is faster as image_copy because it doesn't copy the whole image buffer.

Parameters
[in,out]*aThe image to switch
[in,out]*bThe image to switch with

Definition at line 97 of file image.c.

Referenced by opticflow_calc_frame().

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void image_to_grayscale ( struct image_t input,
struct image_t output 
)

Convert an image to grayscale.

Depending on the output type the U/V bytes are removed

Parameters
[in]*inputThe input image (Needs to be YUV422)
[out]*outputThe output image

Definition at line 116 of file image.c.

References image_t::buf, dest, image_t::h, IMAGE_YUV422, image_t::ts, image_t::type, and image_t::w.

Referenced by cv_window_func(), detect_window(), and opticflow_calc_frame().

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uint16_t image_yuv422_colorfilt ( struct image_t input,
struct image_t output,
uint8_t  y_m,
uint8_t  y_M,
uint8_t  u_m,
uint8_t  u_M,
uint8_t  v_m,
uint8_t  v_M 
)

Filter colors in an YUV422 image.

Parameters
[in]*inputThe input image to filter
[out]*outputThe filtered output image
[in]y_mThe Y minimum value
[in]y_MThe Y maximum value
[in]u_mThe U minimum value
[in]u_MThe U maximum value
[in]v_mThe V minimum value
[in]v_MThe V maximum value
Returns
The amount of filtered pixels

Definition at line 149 of file image.c.

References image_t::buf, dest, image_t::h, image_t::ts, and image_t::w.

Referenced by colorfilter_func().

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void image_yuv422_downsample ( struct image_t input,
struct image_t output,
uint16_t  downsample 
)

Simplified high-speed low CPU downsample function without averaging downsample factor must be 1, 2, 4, 8 ...

2^X image of typ UYVY expected. Only one color UV per 2 pixels

we keep the UV color of the first pixel pair and sample the intensity evenly 1-3-5-7-... or 1-5-9-...

input: u1y1 v1y2 u3y3 v3y4 u5y5 v5y6 u7y7 v7y8 ... downsample=1 u1y1 v1y2 u3y3 v3y4 u5y5 v5y6 u7y7 v7y8 ... downsample=2 u1y1v1 (skip2) y3 (skip2) u5y5v5 (skip2 y7 (skip2) ... downsample=4 u1y1v1 (skip6) y5 (skip6) ...

Parameters
[in]*inputThe input YUV422 image
[out]*outputThe downscaled YUV422 image
[in]downsampleThe downsampel facter (must be downsample=2^X)

Definition at line 213 of file image.c.

References image_t::buf, dest, image_t::h, image_t::ts, and image_t::w.

Referenced by viewvideo_function().

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