Functions
I32	mirror_hor (image src, image dst)
	Mirror Image Horizontally. More...

I32	mirror_ver (image src, image dst)
	Mirror Image Vertically. More...

I32	rotate90l (image src, image dst)
	Rotate Image by 90 Degrees Counter-Clockwise. More...

I32	rotate90r (image src, image dst)
	Rotate Image by 90 Degrees Clockwise. More...

I32	rotate180 (image src, image dst)
	Rotate Image by 180 Degrees. More...

void	xshear (image src, F32 shear, image dst, F32 offset, U8 bgnd)
	Horizontal Image Shear. More...

I32	move_image_alpha (image src, image dst, F32 mx, F32 my, U8 bgnd)
	Subpixel Interpolated XY-Movement of Image. More...

I32	pyramidx (image a, image b, void(*func)())
	Pyramid Reduction for Images. More...

I32	pyramidc (image a, image b, void(*func)())
	Pyramid Reduction for Color Images. More...

void	subsample (image a, image b, I32 rh, I32 rv)
	Subsampling of Images. More...

void	zoom_up (image a, image b, I32 factor)
	Enlargement of an Image. More...

void	zoom_up_xy (image a, image b, I32 fx, I32 fy)
	Enlargement of an Image. More...

I32	threepoint_calculate (point p0, point p1, point p2, point q0, point q1, point q2, F32 *a, F32 t)
	Calculates the Inverse Affine Transformation Matrix for 2×3 Coordinate Points. More...

void	calc_rotation_matrix (F32 angle, F32 cx, F32 cy, F32 a[2][2], F32 t[2])
	Calculates the Inverse Rotation Matrix and Vector for a Clockwise Rotation around a Center Point. More...

void	calc_rotation (F32 angle, point p, point target_p, F32 a[2][2], F32 t[2])
	Sample Point driven Calculation of the Inverse Rotation Matrix and Vector for a Clockwise Rotation. More...

I32	affine_image_transform (image src, image dst, F32 a[2][2], F32 t[2], U8 bgnd)
	Subpixel Interpolated (Inverse) Affine Image Transformation. More...

I32	affine_image_transform2 (image src, image dst, F32 a[2][2], F32 t[2], U8 bgnd)
	Subpixel Interpolated (Inverse) Affine Image Transformation using float. More...

I32	affine_image_transform3 (image src, image dst, F32 a[2][2], F32 t[2], U8 bgnd)
	Quadratic Subpixel Interpolated (Inverse) Affine Image Transformation using Integers. More...

I32	affine_pixellist_transform (I32 src, I32 dst, U32 pxCount, F32 a[2][2], F32 t[2])
	Pixellist (Inverse) Affine Transformation. More...

I32	vc_line_greys (U8 px, I32 pxCnt, I32 pxMaxBytes, image a, I32 x1In, I32 y1In, I32 x2In, I32 y2In, I32 x1UsedOrNULL, I32 y1UsedOrNULL, I32 x2UsedOrNULL, I32 *y2UsedOrNULL)
	Grey Value Extraction at a Bresenham Line of an Image. More...

I32	vc_line_greys_scaled (U8 px, I32 pxCnt, I32 pxMaxBytes, image a, F32 x1In, F32 y1In, F32 x2In, F32 y2In, I32 scale, F32 x1UsedOrNULL, F32 y1UsedOrNULL, F32 x2UsedOrNULL, F32 *y2UsedOrNULL)
	Grey Value Extraction at a Bresenham Line of an Image (subpixel interpolated scale) More...

I32	resample_image (image src, image dst, I32(*func)())
	Subpixel Interpolated Image Resampling Transformation. More...

#define	pyramid(a, b) pyramidx(a, b, (void (*)())FL_2x2_PAV_U8P_U8P)
	Pyramid Filter for Image Variable. More...

#define	pyr_max(a, b) pyramidx(a, b, (void (*)())FL_2x2_PMX_U8P_U8P)
	Pyramid Filter Maximum for Image Variable. More...

#define	pyr_min(a, b) pyramidx(a, b, (void (*)())FL_2x2_PMN_U8P_U8P)
	Pyramid Filter Minimum for Image Variable. More...

#define	pyr_col(a, b) pyramidc(a, b, (void (*)())FL_2x2_PAC_U8P_U8P)
	Pyramid Averaging Filter for Bayer Pattern Image Variable. More...

I32	AffineInitTable (I32 mode)
	Allocates and Initializes a Unit Vector Table for Affine Biquadratic Transform. More...

void	AffineDeinitTable ()
	Deallocates the Interpolation Table for Affine Biquadratic Transform. More...

#define	resample_bilinear(src, dst) resample_image(src, dst, (I32 (*)())affine_image_transform)
	Image Resampling to the Destination Image Size Using Bilinear Interpolation (Macro). More...

#define	resample_quadratic(src, dst) resample_image(src, dst, (I32 (*)())affine_image_transform3)
	Image Resampling to the Destination Image Size Using Quadratic Interpolation (Macro). More...

Detailed Description

Affine transformations map pixels to different pixels using a linear mapping. All affine transformations can be specified by the following formula:

$\left( \begin{array}{c} x_\textrm{dst} \\ y_\textrm{dst} \end{array} \right) = \left( \begin{array}{cc} a_{00} & a_{01} \\ a_{10} & a_{11} \end{array} \right) \left( \begin{array}{c} x_\textrm{src} \\ y_\textrm{src} \end{array} \right) + \left( \begin{array}{c} t_0 \\ t_1 \end{array} \right),$

where

$(x_\textrm{src}, y_\textrm{src})^T$ is the coordinate of the source pixel,
$(x_\textrm{dst}, y_\textrm{dst})^T$ is the coordinate of the destination pixel,
$a_{00}, a_{01}, a_{10}, a_{11}$ are coefficients of the transformation matrix, and
is the displacement vector.

With the above formula any combination of the following transformation may be performed:

displacement (movement) parallel to x and y axis
rotation with an arbitrary rotation center point
shear
size scaling (zoom up / down) in x and y separately
mirroring

For the function affine_image_transform() the inverse transformation matrix is used. The functions calc_rotation_matrix(), calc_rotation() and threepoint_calculate() return the inverse matrix and vector which can than be used by the affine_image_transform() routine:

$\begin{eqnarray*} \left( \begin{array}{c} x_\textrm{src} \\ y_\textrm{src} \end{array} \right) &= \left( \begin{array}{cc} a_{00} & a_{01} \\ a_{10} & a_{11} \end{array} \right)^{-1} \left( \begin{array}{c} x_\textrm{dst} \\ y_\textrm{dst} \end{array} \right) &- \left[\left( \begin{array}{cc} a_{00} & a_{01} \\ a_{10} & a_{11} \end{array} \right)^{-1} \left( \begin{array}{c} t_0 \\ t_1 \end{array} \right) \right]\\ &=: \left( \begin{array}{cc} b_{00} & b_{01} \\ b_{10} & b_{11} \end{array} \right) \left( \begin{array}{c} x_\textrm{dst} \\ y_\textrm{dst} \end{array} \right) &+ \left( \begin{array}{c} u_0 \\ u_1 \end{array} \right), \end{eqnarray*}$

where

$b_{00}, b_{01}, b_{10}, b_{11}$ are coefficients of the inverse transformation matrix, and
is the 'inverse' displacement vector.

Macro Definition Documentation

◆ pyramid

#define pyramid	(	a,
		b
	)	pyramidx(a, b, (void (*)())FL_2x2_PAV_U8P_U8P)

The macro computes the pyramid filter operation of an image defined by image variable a. The result is stored in image b.

a1	a2
a3	a4

Four values of the source image are combined to one pixel of the destination image according to the following formula:

$\textrm{result} = (a1, a2, a3, a4)/4$

pyramid() is a macro which calls pyramidx() with basic function FL_2x2_PAV_U8P_U8P() as an argument.

◆ pyr_max

#define pyr_max	(	a,
		b
	)	pyramidx(a, b, (void (*)())FL_2x2_PMX_U8P_U8P)

The macro computes the pyramid filter operation of an image defined by image variable a. The result is stored in image b.

a1	a2
a3	a4

Four values of the source image are combined to one pixel of the destination image according to the following formula:

$\textrm{result} = \textrm{max}(a1, a2, a3, a4)$

pyr_max() is a macro which calls pyramidx() with basic function FL_2x2_PMX_U8P_U8P() as an argument.

◆ pyr_min

#define pyr_min	(	a,
		b
	)	pyramidx(a, b, (void (*)())FL_2x2_PMN_U8P_U8P)

The macro computes the pyramid filter operation of an image defined by image variable a. The result is stored in image b.

a1	a2
a3	a4

Four values of the source image are combined to one pixel of the destination image according to the following formula:

$\textrm{result} = \textrm{min}(a1, a2, a3, a4)$

pyr_min() is a macro which calls pyramidx() with basic function FL_2x2_PMN_U8P_U8P() as an argument.

◆ pyr_col

#define pyr_col	(	a,
		b
	)	pyramidc(a, b, (void (*)())FL_2x2_PAC_U8P_U8P)

This macro performs a pyramid reduction for color images coded as a bayer pattern image: 2×2 pixels of source are averaged and written to 1 pixel at the destination image.

pyr_col() is a macro which calls pyramidc() with basic function FL_2x2_PAC_U8P_U8P() as an argument.

◆ resample_bilinear

#define resample_bilinear	(	src,
		dst
	)	resample_image(src, dst, (I32 (*)())affine_image_transform)

The macro resamples the source image content to the dimensions of the destination image using a bilinear interpolation.

Parameters

src	Points to Source Image.
dst	Points to Destination Image.

resample_bilinear() is a macro which calls resample() with basic function affine_image_transform() as an argument.

◆ resample_quadratic

#define resample_quadratic	(	src,
		dst
	)	resample_image(src, dst, (I32 (*)())affine_image_transform3)

The macro resamples the source image content to the dimensions of the destination image using a quadratic interpolation.

Parameters

src	Points to Source Image.
dst	Points to Destination Image.

resample_bilinear() is a macro which calls resample() with basic function affine_image_transform3() as an argument.

Function Documentation

◆ mirror_hor()

I32 mirror_hor	(	image *	src,
		image *	dst
	)

The function mirrors an image horizontally with respect to its central axis. It is possible to use the function in-place, i.e. source and destination images may be identical. In this case, the function uses a slightly faster exchange-and-reverse routine.

If source and destination images are not identical but overlap, the result is not defined. The function mirrors the whole image if src and dst image have equal dimensions. If this is not the case, only a fraction of the source image is mirrored with the following dimensions: dx = min( src->dx, dst->dx), dy = min( src->dy, dst->dy)

Memory Consumption: None.

See also: mirror_ver().

Return values

ERR_NONE on Success.

◆ mirror_ver()

I32 mirror_ver	(	image *	src,
		image *	dst
	)

The function mirrors an image vertically with respect to its central axis. It is possible to use the function in-place, i.e. source and destination images may be identical. In this case, the function uses a slightly faster exchange-and-reverse routine.

If source and destination images are not identical but overlap, the result is not defined. The function mirrors the whole image if src and dst image have equal dimensions. If this is not the case, only a fraction of the source image is mirrored with the following dimensions: dx = min( src->dx, dst->dx), dy = min( src->dy, dst->dy).

Memory Consumption: None.

See also: mirror_hor().

Return values

ERR_NONE on Success.

◆ rotate90l()

I32 rotate90l	(	image *	src,
		image *	dst
	)

The function rotates an image by 90 degrees counter-clockwise. It is not possible to use the function in-place, i.e. source and destination images must not overlap.

The function rotates the whole image if src and dst image have equal dimensions.

If this is not the case, only a fraction of the source image is rotated with the following dimensions:

dx = min( src->dx, dst->dy) dy = min( src->dy, dst->dx).

The function splits the source image into tiles which can be processed very efficiently even with limited cache memory size.

Memory Consumption: None.

See also: rotate90r(), rotate180().

Return values

ERR_TYPE	if Image Types are not identical or wrong.
ERR_NONE	on Success.

◆ rotate90r()

I32 rotate90r	(	image *	src,
		image *	dst
	)

The function rotates an image by 90 degrees clockwise.

Please refer to the documentation of rotate90l() for the details.

Memory Consumption: None.

See also: rotate90l(), rotate180().

Return values

ERR_TYPE	if Image Types are not identical or wrong.
ERR_NONE	on Success.

◆ rotate180()

I32 rotate180	(	image *	src,
		image *	dst
	)

The function rotates an image by 180 degrees. It is possible to use the function in-place, i.e. source and destination images may be identical. In this case, the function uses a slightly faster exchange-and-reverse routine.

If source and destination images are not identical but overlap, the result is not defined. The function rotates the whole image if src and dst image have equal dimensions.

If this is not the case, only a fraction of the source image is rotated with the following dimensions:

dx = min( src->dx, dst->dx), dy = min( src->dy, dst->dy).

Memory Consumption: None.

See also: rotate90l(), rotate90r().

Return values

ERR_NONE on Success.

◆ xshear()

void xshear	(	image *	src,
		F32	shear,
		image *	dst,
		F32	Offset,
		U8	bgnd
	)

The function performs a horizontal image shear of the source image by a shear factor of shear. A horizontal displacement offset offset may be added. Pixels for which the corresponding source image is not defined, are set to bgnd.

If source and destination images are not identical but overlap, the result is not defined.

Memory Consumption: None.

See also: yshear().

◆ move_image_alpha()

I32 move_image_alpha	(	image *	src,
		image *	dst,
		float	mx,
		float	my,
		U8	bgnd
	)

The function moves an image by a fractional number of pixels in x and y direction using bilinear interpolation.

The offset vector (mx, my) is added to the start of source image. The image is then copied using bilinear interpolation. If (mx, my) = (0, 0), the result of the operation is the same as for the copy() function. The resulting image always has the dimensions of the destination image. Missing areas are set to bgnd. The function also performs a bilinear interpolation between edges of the source image and the background color where applicable.

It is possible to use the function in-place if my<0, otherwise the result is not defined.

Parameters

src	Pointer to Source Image.
dst	Pointer to Destination Image.
mx	Movement Vector x, `mx` > 0: Movement to Right.
my	Movement Vector y, `my` > 0: Downward Movement.
bgnd	Background Color.

Memory Consumption: is dst->dx Bytes Maximum.

See also: rotate90l(), rotate90r(), rotate180().

Return values

ERR_FORMAT	if `src` or `dst` is NULL.
ERR_MEMORY	if Memory Allocation fails.
ERR_NONE	on Success.

◆ pyramidx()

I32 pyramidx	(	image *	a,
		image *	b,
		void(*)()	func
	)

The function computes the pyramid filter operation of an image defined by image variable a. The result is stored in image b.

a1	a2
a3	a4

Four values of the source image are combined to one pixel of the destination image. The nature of the operation is defined by the basic function func().

The following macros use this function:

Call	Basic function
pyramid(a, b)	FL_2x2_PAV_U8P_U8P()
pyr_max(a, b)	FL_2x2_PMX_U8P_U8P()
pyr_min(a, b)	FL_2x2_PMN_U8P_U8P()

Please note that the result image is smaller by the factor of two in both the horizontal and vertical direction. The operation may be performed in-place, i.e. a and b may be equal.

Memory Consumption: None.

See also: pyramid(), pyr_max(), pyr_min(), subsample().; zoom_up() for the opposite way.

Return values

ERR_TYPE	if not Grey Compatible Image.
ERR_NONE	on Success.

◆ pyramidc()

I32 pyramidc	(	image *	src,
		image *	dst,
		void(*)()	func
	)

This function performs a pyramid reduction for color images coded as a bayer pattern image.

The following macros are available:

Call	Basic function
pyr_col(a, b)	FL_2x2_PAC_U8P_U8P()

Please note that the result image is smaller by the factor of two in both the horizontal and vertical direction.

The operation may be performed in-place, i.e. src and dst may be equal.

Memory Consumption: none

Parameters

src	Source Image of Type IMAGE_BAYER.
dst	Destination Image of Type IMAGE_BAYER.
func	Points to Low-level Pyramid Function.

See also: pyramid(), pyr_max(), pyr_min(), subsample()

Return values

ERR_TYPE	if Image Type is not IMAGE_BAYER.
ERR_NONE	on Success.

◆ subsample()

void subsample	(	image *	a,
		image *	b,
		I32	rh,
		I32	rv
	)

The function copies the image defined by image variable a into image variable b and reduces its size. rh and rv specify the horizontal (rh) and vertical (rv) subsampling ratio.

Constraints: rh, rv > 0

rh=2 means that every other pixel of an original image line will be taken and stored to the result image. The horizontal image width of the result image will be half the source image width.

Memory Consumption: None.

See also: pyramid().

◆ zoom_up()

void zoom_up	(	image *	a,
		image *	b,
		I32	factor
	)

The function enlarges the pixels in image variable a by factor and stores the result in image variable b. If the size of b is not sufficient for this operation the maximum size will be truncated to the size of b.

Memory Consumption: None.

See also: pyramid() for the opposite way.

◆ zoom_up_xy()

void zoom_up_xy	(	image *	a,
		image *	b,
		I32	fx,
		I32	fy
	)

The function enlarges the pixels in image variable a by factors fx and fy and stores the result in image variable b. If the size of b is not sufficient for this operation the maximum size will be truncated to the size of b.

Memory Consumption: None.

◆ threepoint_calculate()

I32 threepoint_calculate	(	point *	p0,
		point *	p1,
		point *	p2,
		point *	q0,
		point *	q1,
		point *	q2,
		F32 **	a,
		F32 *	t
	)

Input to the function are three known points in the original coordinate system and their image points in the transformed coordinate system.

See also: Bernd Jaehne, practical handbook on image processing for scientific applications pp 268-270.

Parameters

[in]	p0,p1,p2	Sample Point Positions before Transformation.
[in]	q0,q1,q2	Sample Point Positions after Transformation.
[out]	a	Inverse 2D Transformation Matrix 2×2.
[out]	t	Inverse 2D Translation Vector 2×1.

Return values

ERR_MEMORY	if Memory Allcoation failed.
ERR_SINGULAR	if Transformation Matrix is Singular.
ERR_NONE	on Success.

◆ calc_rotation_matrix()

void calc_rotation_matrix	(	F32	angle,
		F32	cx,
		F32	cy,
		F32	a[2][2],
		F32	t[2]
	)

The function calculates the inverse rotation matrix a[2][2] and the translation vector t[2] for a clockwise rotation with respect to a given center point. Matrix a may then be used, for example, by affine_image_transform().

Parameters

[in]	angle	Angle for Clockwise Rotation in Degrees.
[in]	cx,cy	Rotation Center Coordinate.
[out]	a	Inverse 2D Transformation Matrix.
[out]	t	Inverse 2D Translation Vector.

◆ calc_rotation()

void calc_rotation	(	F32	angle,
		point *	p,
		point *	target_p,
		F32	a[2][2],
		F32	t[2]
	)

The function calculates the inverse rotation matrix a[2][2] and the translation vector t[2] for a clockwise rotation with respect to a given angle and a sample mapping going from position p to the position target_p.

An important special case is p = target_p = center of rotation.

Parameters

[in]	angle	Angle for Clockwise Rotation in Degrees.
[in]	p	Sample Coordinate Position before Rotation.
[in]	target_p	Sample Coordinate Position after Rotation.
[out]	a	Inverse 2D Transformation Matrix.
[out]	t	Inverse 2D Translation Vector.

◆ affine_image_transform()

I32 affine_image_transform	(	image *	src,
		image *	dst,
		float	a[2][2],
		float	t[2],
		U8	bgnd
	)

This function performs a general affine image transformation on the source image and outputs the result to the destination image. The function uses bilinear interpolation.

The resulting image always has the dimensions of the destination image. Missing areas are set to bgnd. Please be aware, that the function needs the inverse transformation matrix and translation vector as an input. It is not possible to use the function in-place, i.e. source and destination images must not overlap.

Parameters

src	Pointer to Source Image.
dst	Pointer to Destination Image.
a	Inverse 2D Transformation Matrix.
t	Inverse 2D Translation Vector.
bgnd	Background Grey Value.

Memory Consumption: None.

See also: affine_image_transform2(), affine_image_transform3(), calc_rotation_matrix().

Return values

ERR_FORMAT	if `src` or `dst` is NULL.
ERR_NONE	on Success.

◆ affine_image_transform2()

I32 affine_image_transform2	(	image *	src,
		image *	dst,
		float	a[2][2],
		float	t[2],
		U8	bgnd
	)

Same as affine_image_transform() but with (slow) floating-point calculation. It is recommmended to use function affine_image_transform() instead. Be aware that the inverse transformation matrix is required.

Parameters

src	pointer to source image
dst	pointer to destination image
a	inverse 2D transformation matrix
t	inverse 2D translation vector
bgnd	background grey value

See also: affine_image_transform(), affine_image_transform3(), calc_rotation_matrix().

Return values

ERR_FORMAT	if `src` or `dst` is NULL.
ERR_NONE	on Success.

◆ affine_image_transform3()

I32 affine_image_transform3	(	image *	src,
		image *	dst,
		float	a[2][2],
		float	t[2],
		U8	bgnd
	)

This function performs a subpixel interpolated affine transformation of image using integer values performing a quadratic interpolation. Be aware that the inverse transformation matrix is required.

This function uses an interpolation table which is allocated and calculated automatically for the first call of the function. The table may be set by the user using the function AffineInitTable(). Please make sure to call the function AffineDeinitTable() when the table is no longer needed.

Parameters

[in]	src	Points to Source Image.
[out]	dst	Points to Destination Image.
[in]	a	Inverse 2D Transformation Matrix.
[in]	t	Inverse 2D Translation Vector.
[in]	bgnd	Background Grey Value.

See also: affine_image_transform(), affine_image_transform2(), calc_rotation_matrix().

Return values

ERR_FORMAT	if `src` or `dst` is NULL.
ERR_TYPE	if Image Variable Type of `src` or `dst` is not of Type IMAGE_GREY, IMAGE_CBCR444, IMAGE_CBCR422, IMAGE_CBCR411, IMAGE_YUVNORM, IMAGE_IHS, IMAGE_VECTOR.
ERR_MEMORY	if Memory Allocation fails.
ERR_NONE	on Success.

◆ affine_pixellist_transform()

I32 affine_pixellist_transform	(	I32 *	src,
		I32 *	dst,
		U32	pxCount,
		float	a[2][2],
		float	t[2]
	)

This function performs a general affine image transformation on the source pixel list and outputs the result to the destination pixel list. Output pixels are rounded to its next integer positions.

Please be aware, that the function needs the inverse transformation matrix and translation vector as an input. It is possible to use the function in-place, i.e. source and destination pixel lists may be identical.

Parameters

src	Pointer to Source Pixel List.
dst	Pointer to Destination Pixel List.
pxCount	Count of Pixels in List.
a	Inverse 2D Transformation Matrix.
t	Inverse 2D Translation Vector.

Memory Consumption: None.

See also: calc_rotation_matrix().

Return values

ERR_NONE always.

◆ AffineInitTable()

I32 AffineInitTable ( I32 mode )

Parameters

mode	Transformation Selector: `mode` = 0: B-Spline, `mode` = 1: Biquadratic (Standard).

Return values

ERR_MEMORY	if Memory Allocation fails.
ERR_NONE	on Success.
ERR_MEMORY	if Memory Allocation fails.
ERR_NONE	on Success.

◆ AffineDeinitTable()

void AffineDeinitTable ( )

The function deallocates the interpolation table for affine transform allocated after calling AffineInitTable().

◆ vc_line_greys()

I32 vc_line_greys	(	U8 *	px,
		I32 *	pxCnt,
		I32	pxMaxBytes,
		image *	a,
		I32	x1In,
		I32	y1In,
		I32	x2In,
		I32	y2In,
		I32 *	x1UsedOrNULL,
		I32 *	y1UsedOrNULL,
		I32 *	x2UsedOrNULL,
		I32 *	y2UsedOrNULL
	)

This function extracts grey values of an image lying at a bresenham line. If the given line exceeds the image, only a partial sub-line will be extracted instead. The first coordinate is the coordinate of x1In, y1In or its replacement if the coordinate exceeds the image. The last coordinate is the coordinate of x2In, y2In or its replacement if the coordinate exceeds the image.

Given with pxMaxBytes the output px array must provide at least max(2 * sizeof(I32), sizeof(U8*)) * (1 + max(abs(x2-x1), abs(y2-y1))) bytes.

Parameters

px,pxCnt	The result grey value array and its entry number
pxMaxBytes	The maximum `px` entries allowed, must be at least max(2 * sizeof(I32), sizeof(U8)) (1 + max(abs(x2-x1), abs(y2-y1))) bytes.
a	The 8-bit grey value image where pixels will be extracted from
x1In,y1In,x2In,y2In	The requested line of coordinates to be extracted
x1UsedOrNULL,y1UsedOrNULL,x2UsedOrNULL,y2UsedOrNULL	Optional pointers to get the sub-line used (you may use `x1In` ... pointers for overwriting)

See also: vc_line_greys_scaled, affine_image_transform(), affine_image_transform3().

◆ vc_line_greys_scaled()

I32 vc_line_greys_scaled	(	U8 *	px,
		I32 *	pxCnt,
		I32	pxMaxBytes,
		image *	a,
		F32	x1In,
		F32	y1In,
		F32	x2In,
		F32	y2In,
		I32	scale,
		F32 *	x1UsedOrNULL,
		F32 *	y1UsedOrNULL,
		F32 *	x2UsedOrNULL,
		F32 *	y2UsedOrNULL
	)

This function extracts grey values of an image lying at a bresenham line. A scale factor can be given for the output: The upscaled bresenham line positions are bilinearly interpolated between the surrounding four pixel coordinates. If the given line exceeds the image, only a partial sub-line will be extracted instead. The first coordinate is the (scale rounded) subpixel coordinate of x1In, y1In or its replacement if the coordinate exceeds the image. The last coordinate is the (scale rounded) subpixel coordinate of x2In, y2In or its replacement if the coordinate exceeds the image.

Given with pxMaxBytes the output px array must provide at least scale * line length bytes, or processing will fail.

Parameters

px,pxCnt	The result grey value array and its entry number
pxMaxBytes	The maximum `px` entries allowed, must be at least scale * line length bytes
a	The 8-bit grey value image where pixels will be extracted from
x1In,y1In,x2In,y2In	The requested line of coordinates to be extracted (rounded to 1/`scale`)
scale	The scale factor used: almost each coordinate at the line `scale` subpixels are interpolated and outputted
x1UsedOrNULL,y1UsedOrNULL,x2UsedOrNULL,y2UsedOrNULL	Optional pointers to get the sub-line used (you may use `x1In` ... pointers for overwriting)

See also: vc_line_greys, affine_image_transform(), affine_image_transform3().

◆ resample_image()

I32 resample_image	(	image *	src,
		image *	dst,
		I32(*)()	func
	)

The source image is resampled to the size of the destination image. Depending on the function pointer used, the operation can be bilinear, biqudratic or differently interpolated.

Parameters

src	Points to Source Image.
dst	Points to Destination Image.
func()	Points to Affine Transformation.

Returns: Standard Error Code.

Affine Image Transformations And Scaling

Functions

Detailed Description

Macro Definition Documentation

◆ pyramid

◆ pyr_max

◆ pyr_min

◆ pyr_col

◆ resample_bilinear

◆ resample_quadratic

Function Documentation

◆ mirror_hor()

◆ mirror_ver()

◆ rotate90l()

◆ rotate90r()

◆ rotate180()

◆ xshear()

◆ move_image_alpha()

◆ pyramidx()

◆ pyramidc()

◆ subsample()

◆ zoom_up()

◆ zoom_up_xy()

◆ threepoint_calculate()

◆ calc_rotation_matrix()

◆ calc_rotation()

◆ affine_image_transform()

◆ affine_image_transform2()

◆ affine_image_transform3()

◆ affine_pixellist_transform()

◆ AffineInitTable()

◆ AffineDeinitTable()

◆ vc_line_greys()

◆ vc_line_greys_scaled()

◆ resample_image()