Description

Provides functionality for easy reading and writing of netbpm images.

Reading and writing of images has been placed into single package. This way writing and reading them is centralized and easier.

Netbpm image format

It is completly designed around netbpm image format. This plain version of this format are ascii based and make them suitable for trivial reading and writing from VHDL. The images can directly be viewed in any image viewer and are very protable and recognized by many tools.

For a description of this format see the Wikipedia page about Netbpm.

Typical reading usage

 -- First read the header
 read_pbmplus_header( pgm_width, pgm_height, max_pixel_value, pgm, file_input_pixel );
 
 -- Then read the pixels
 read_pixel(file_input_pixel, pixel_tmp, end_of_file);

Typical writing usage

 -- First write the header
 write_pbmplus_header( pgm_width, pgm_height, max_pixel_value, pgm, file_output_pixel );

 -- Then write the pixels
 write_pixel( val, file_output_pixel);

Package Body >> image_io_pkg

Functions
string	pad_string ( arg_str: in string ret_len_c: in natural 10 fill_char_c: in character ' ' )

Procedures
	read_pbmplus_header( constant exp_width: in integer constant exp_height: in integer constant exp_max_value: in integer constant exp_type_of_pbm: in pbmplustype )
	Generic procedure for reading pbm plus headers.
	write_pbmplus_header( constant p_width: in integer constant p_height: in integer constant max_value: in integer constant type_of_pbm: in pbmplustype )
	generic procedure for writing pbm plus headers
	read_pixel( variable pixel: out integer ,signal end_of_file: out std_logic )
	generic procedure for reading single pixel value from pbm file to variable
	read_pixel( signal pixel: out std_logic_vector ,signal end_of_file: out std_logic )
	generic procedure for reading single pixel value from pbm file to signal
	read_rgb_pixel( variable pixel_r: out integer variable pixel_g: out integer variable pixel_b: out integer signal end_of_file: out std_logic )
	generic procedure to read rgb variable from a file
	read_rgb_pixel( signal pixel_r: out std_logic_vector ( wordsize - 1 downto 0 ) signal pixel_g: out std_logic_vector ( wordsize - 1 downto 0 ) signal pixel_b: out std_logic_vector ( wordsize - 1 downto 0 ) signal end_of_file: out std_logic )
	write_pixel( variable pixel: in integer )
	generic procedure for writing single pixel value from variable to pbm file
	write_pixel( signal pixel: in std_logic_vector )
	generic procedure for writing single pixel value from signal to pbm file
	write_bin_pixel( variable pixel: in boolean )
	write_bin_pixel( signal pixel: in std_logic )
	write_rgb_pixel( variable pixel_r: in integer variable pixel_g: in integer variable pixel_b: in integer )
	write_rgb_pixel( signal pixel_r: in unsigned ( 7 downto 0 ) signal pixel_g: in unsigned ( 7 downto 0 ) signal pixel_b: in unsigned ( 7 downto 0 ) )
	write_ycbcr_pixel( variable pixel_y: in integer variable pixel_cb: in integer variable pixel_cr: in integer )
	write_ycbcr_pixel( signal pixel_y: in unsigned ( 9 downto 0 ) signal pixel_cb: in unsigned ( 9 downto 0 ) signal pixel_cr: in unsigned ( 9 downto 0 ) )
	rgb_to_ycbcr( variable r: in unsigned ( 7 downto 0 ) variable g: in unsigned ( 7 downto 0 ) variable b: in unsigned ( 7 downto 0 ) variable y: out unsigned ( 9 downto 0 ) variable cb: out unsigned ( 9 downto 0 ) variable cr: out unsigned ( 9 downto 0 ) )
	procedure to convert rgb variables into corresponding ycbcr components
	ycbcr_to_rgb( variable y: in unsigned ( 9 downto 0 ) variable cb: in unsigned ( 9 downto 0 ) variable cr: in unsigned ( 9 downto 0 ) variable r: out unsigned ( 7 downto 0 ) variable g: out unsigned ( 7 downto 0 ) variable b: out unsigned ( 7 downto 0 ) )
	procedure to convert ycbcr variables into corresponding rgb components

Libraries
ieee
	use standard library

Use Clauses
std_logic_1164
	use std_logic_vector
numeric_std
	needed for colorscheme calculations
textio
	used for writing and reading images
math_real
	used only for calculation of constants

Constants
wordsize	integer := 8
	Number of bits in a pixel.

Types
pbmplustype	( pbm , pgm , ppm )
	Enumeration for type of pbm.

Member Function Documentation

§ pad_string()

string pad_string	(	arg_str in string ,
		ret_len_c in natural 10 ,
		fill_char_c in character ' '
	)

Function

function to pad strings with a fill character

Parameters

[in]	arg_str	the input string that has to be padded
[in]	ret_len_c	the length of the output string. (must be larger than length of the input string)
[in]	fill_char_c	the filling character that should be used to pad the input string

Returns: string arg_str padded up to length ret_len_c with charachter fill_char_c

§ read_pbmplus_header()

read_pbmplus_header	(	constant	exp_width in integer ,
		constant	exp_height in integer ,
		constant	exp_max_value in integer ,
		constant	exp_type_of_pbm in pbmplustype
	)

Procedure

Generic procedure for reading pbm plus headers.

Reads the header from a file and compares the read values to the expected files, by using this it can be asserted the correct input image was provided

Parameters

[in]	exp_width	Expected width in number of pixels
[in]	exp_height	Expected height in number of pixels
[in]	exp_max_value	Expected maximum value
[in]	exp_type_of_pbm	Expected pbmplustype

§ read_pixel() [1/2]

read_pixel	(	variable	pixel out integer ,
		signal	end_of_file out std_logic
	)

Procedure

generic procedure for reading single pixel value from pbm file to variable

Reads a single pixel every call from the specified file and outputs it as variable

Parameters

[in]	pbmplus_file	file to read from
[out]	pixel	variable to place value in
[out]	end_of_file	signal that is true when end_of_file is reached

§ read_pixel() [2/2]

read_pixel	(	signal	pixel out std_logic_vector ,
		signal	end_of_file out std_logic
	)

Procedure

generic procedure for reading single pixel value from pbm file to signal

Reads a single pixel every call from the specified file

Parameters

[in]	pbmplus_file	file to read from
[out]	pixel	signal to place value in
[out]	end_of_file	signal that is true when end_of_file is reached

§ read_rgb_pixel() [1/2]

read_rgb_pixel	(	variable	pixel_r out integer ,
		variable	pixel_g out integer ,
		variable	pixel_b out integer ,
		signal	end_of_file out std_logic
	)

Procedure

generic procedure to read rgb variable from a file

Reads a single rgb pixel every call from the specified file and outputs it as seperate variable per color channel.

Parameters

[in]	pbmplus_file	file to read from
[out]	pixel_r	variable to place red pixel value in
[out]	pixel_g	variable to place green pixel value in
[out]	pixel_b	variable to place blue pixel value in
[out]	end_of_file	signal that is true when end_of_file is reached

§ read_rgb_pixel() [2/2]

read_rgb_pixel	(	signal	pixel_r out std_logic_vector( wordsize - 1 downto 0 ) ,
		signal	pixel_g out std_logic_vector( wordsize - 1 downto 0 ) ,
		signal	pixel_b out std_logic_vector( wordsize - 1 downto 0 ) ,
		signal	end_of_file out std_logic
	)

Procedure

Reads a single rgb pixel every call from the specified file and outputs it as seperate signal per color channel.

Parameters

[in]	pbmplus_file	file to read from
[out]	pixel_r	signal to place red pixel value in
[out]	pixel_g	signal to place green pixel value in
[out]	pixel_b	signal to place blue pixel value in
[out]	end_of_file	signal that is true when end_of_file is reached

§ rgb_to_ycbcr()

rgb_to_ycbcr	(	variable	r in unsigned( 7 downto 0 ) ,
		variable	g in unsigned( 7 downto 0 ) ,
		variable	b in unsigned( 7 downto 0 ) ,
		variable	y out unsigned( 9 downto 0 ) ,
		variable	cb out unsigned( 9 downto 0 ) ,
		variable	cr out unsigned( 9 downto 0 )
	)

Procedure

procedure to convert rgb variables into corresponding ycbcr components

§ write_bin_pixel() [1/2]

write_bin_pixel	(	variable	pixel in boolean
	)

Procedure

generic procedure to write binary variable of a file the header must be written with pbm as image type

§ write_bin_pixel() [2/2]

write_bin_pixel	(	signal	pixel in std_logic
	)

Procedure

generic procedure to write binary signal of a file the header must be written with pbm as image type

§ write_pbmplus_header()

write_pbmplus_header	(	constant	p_width in integer ,
		constant	p_height in integer ,
		constant	max_value in integer ,
		constant	type_of_pbm in pbmplustype
	)

Procedure

generic procedure for writing pbm plus headers

Parameters

[in]	p_width	Width in number of pixels
[in]	p_height	Height in number of pixels
[in]	max_value	Maximum value
[in]	type_of_pbm	pbmplustype

§ write_pixel() [1/2]

write_pixel	(	variable	pixel in integer
	)

Procedure

generic procedure for writing single pixel value from variable to pbm file

§ write_pixel() [2/2]

write_pixel	(	signal	pixel in std_logic_vector
	)

Procedure

generic procedure for writing single pixel value from signal to pbm file

§ write_rgb_pixel() [1/2]

write_rgb_pixel	(	variable	pixel_r in integer ,
		variable	pixel_g in integer ,
		variable	pixel_b in integer
	)

Procedure

generic procedure to write rgb variable of a file the header must be written with ppm as image type

§ write_rgb_pixel() [2/2]

write_rgb_pixel	(	signal	pixel_r in unsigned( 7 downto 0 ) ,
		signal	pixel_g in unsigned( 7 downto 0 ) ,
		signal	pixel_b in unsigned( 7 downto 0 )
	)

Procedure

generic procedure to write rgb signal of a file the header must be written with ppm as image type

§ write_ycbcr_pixel() [1/2]

write_ycbcr_pixel	(	variable	pixel_y in integer ,
		variable	pixel_cb in integer ,
		variable	pixel_cr in integer
	)

Procedure

generic procedure to write ycbcr variable of a file the header must be written with ppm as image type

§ write_ycbcr_pixel() [2/2]

write_ycbcr_pixel	(	signal	pixel_y in unsigned( 9 downto 0 ) ,
		signal	pixel_cb in unsigned( 9 downto 0 ) ,
		signal	pixel_cr in unsigned( 9 downto 0 )
	)

Procedure

generic procedure to write ycbcr signal of a file the header must be written with ppm as image type

§ ycbcr_to_rgb()

ycbcr_to_rgb	(	variable	y in unsigned( 9 downto 0 ) ,
		variable	cb in unsigned( 9 downto 0 ) ,
		variable	cr in unsigned( 9 downto 0 ) ,
		variable	r out unsigned( 7 downto 0 ) ,
		variable	g out unsigned( 7 downto 0 ) ,
		variable	b out unsigned( 7 downto 0 )
	)

Procedure

procedure to convert ycbcr variables into corresponding rgb components

Member Data Documentation

§ ieee

ieee

Library

use standard library

§ math_real

math_real

Package

used only for calculation of constants

§ numeric_std

numeric_std

Package

needed for colorscheme calculations

§ pbmplustype

pbmplustype ( pbm , pgm , ppm )

Type

Enumeration for type of pbm.

There are three types of pbm available, these types are specified in the table below

Type	Description
pbm	Supports monochrome bitmaps (1 bit per pixel).
pgm	Supports greyscale images. Reads either pbm or pgm formats and writes pgm format.
ppm	Supports full-color images. Reads either pbm, pgm, or ppm formats, writes ppm format.

§ std_logic_1164

std_logic_1164

Package

use std_logic_vector

§ textio

textio

Package

used for writing and reading images

§ wordsize

wordsize integer := 8

Constant

Number of bits in a pixel.

The documentation for this class was generated from the following file:

/home/ben/Programming/VHDL/realtimestagram/src/common/src/image_io_pkg.vhd

Description

Netbpm image format

Typical reading usage

Typical writing usage

Functions

Procedures

Libraries

Use Clauses

Constants

Types

Member Function Documentation

§ pad_string()

§ read_pbmplus_header()

§ read_pixel() [1/2]

§ read_pixel() [2/2]

§ read_rgb_pixel() [1/2]

§ read_rgb_pixel() [2/2]

§ rgb_to_ycbcr()

§ write_bin_pixel() [1/2]

§ write_bin_pixel() [2/2]

§ write_pbmplus_header()

§ write_pixel() [1/2]

§ write_pixel() [2/2]

§ write_rgb_pixel() [1/2]

§ write_rgb_pixel() [2/2]

§ write_ycbcr_pixel() [1/2]

§ write_ycbcr_pixel() [2/2]

§ ycbcr_to_rgb()

Member Data Documentation

§ ieee

§ math_real

§ numeric_std

§ pbmplustype

§ std_logic_1164

§ textio

§ wordsize