Image Simulation

Functions
cpl_error_code	clipm_image_sim_noise_gaussian (cpl_image *img_modified, const cpl_size window_xxyy[4], double sigma)
	Add white gaussian noise to an image. More...
cpl_error_code	clipm_image_sim_circle (cpl_image *img_modified, double centre_x, double centre_y, double radius, double brightness)
	Add a circle to an existing image (additively, on top). More...
cpl_error_code	clipm_image_sim_rectangle (cpl_image *img_modified, double centre_x, double centre_y, double angle, double length, double width, double brightness)
	Add a circle to an existing image (additively, on top). More...

Detailed Description

This module provides tool functions for the simulation of image content. They are intended to create test images.

Synopsis:

#include "clipm_image_sim.h"
 * 

Function Documentation

cpl_error_code clipm_image_sim_circle	(	cpl_image *	img_modified,
		double	centre_x,
		double	centre_y,
		double	radius,
		double	brightness
	)

Add a circle to an existing image (additively, on top).

Parameters

img_modified	Input image to modify (FITS convention)
centre_x	X centre
centre_y	Y centre
radius	Radius, if = 0, nothing is done
brightness	Filling brightness

Returns

CPL error code

Principle:

• A filled circle is added on top of the existing image content.
• radius can be negative, in this case nothing is done.
• The centre may lie outside the image.

Bad Pixel Handling:

Since the circle is added to the existing image content, only good pixels will be modified.

Error Handling:

The following errors can be set and returned:

• CPL_ERROR_NULL_INPUT: img_modified is NULL
• CPL_ERROR_INVALID_TYPE: img_modified is not of type CPL_TYPE_INT, CPL_TYPE_FLOAT or CPL_TYPE_DOUBLE

Todo:

• implement unit test

cpl_error_code clipm_image_sim_noise_gaussian	(	cpl_image *	img_modified,
		const cpl_size	window_xxyy[4],
		double	sigma
	)

Add white gaussian noise to an image.

Parameters

img_modified	Image
window_xxyy	(Optional) Coordinate buffer of the form {xa, xb, ya, yb}, can be NULL, minimum/maximum order is irrelevant
sigma	Noise sigma, must be > 0

Returns

CPL error code

Principle:

• An existing image must be passed.
• Gaussian noise is added to the pixels with the corresponding sigma value.
• The added absolute noise values are limited to 4*sigma to produce a reliable value range for testing.

Bad Pixel Handling:

Bad pixels are ignored (the data buffer is not modified at these locations).

Error Handling:

The following errors can be set and returned:

• CPL_ERROR_NULL_INPUT: image is NULL
• CPL_ERROR_ILLEGAL_INPUT: sigma <= 0
• CPL_ERROR_INVALID_TYPE: image is not of type CPL_TYPE_INT, CPL_TYPE_FLOAT or CPL_TYPE_DOUBLE
• CPL_ERROR_ACCESS_OUT_OF_RANGE: window_xxyy specifies coordinates outside the image plane

Todo:

• implement unit test

cpl_error_code clipm_image_sim_rectangle	(	cpl_image *	img_modified,
		double	centre_x,
		double	centre_y,
		double	angle,
		double	length,
		double	width,
		double	brightness
	)

Add a circle to an existing image (additively, on top).

Parameters

img_modified	Input image to modify (FITS convention)
centre_x	X centre
centre_y	Y centre
angle	Orientation (mathematically positive, i.e. counterclockwise)
length	Length, will point into the direction of angle
width	Width
brightness	Filling brightness

Returns

CPL error code

Principle:

• A filled rectangle is added on top of the existing image content.
• The centre may lie outside the image.

Bad Pixel Handling:

Since the rectangle is added to the existing image content, only good pixels will be modified.

Error Handling:

The following errors can be set and returned:

• CPL_ERROR_NULL_INPUT: img_modified is NULL
• CPL_ERROR_INVALID_TYPE: img_modified is not of type CPL_TYPE_INT, CPL_TYPE_FLOAT or CPL_TYPE_DOUBLE

Todo:

• implement unit test