image_scale ( : : Row, Column, ScaleHeight, ScaleWidth : )

Modify the current transformation matrix by a scaling.

image_scale modifies the current transformation matrix by applying a scaling. The current transformation matrix is used in image_transform__ for an arbitrary affine transformation of an image. The scaling is addeed to any other modifications of the CTM effected by image_scale, image_translate, or image_rotate. If this is not desired, image_identity must be called before calling image_scale. The point (Row,Column) determines the center of the scaling. ScaleHeight and ScaleWidth determine the vertical and horizontal scale factors, respectively.


Parameters

Row (input_control)
point.y -> real / integer
Row coordinate of the center of the scaling.
Default value: 256
Suggested values: 0, 128, 256, 512
Range of values: 0 <= Row <= 512
Minimum increment: 1
Recommended increment: 10

Column (input_control)
point.x -> real / integer
Column coordinate of the center of the scaling.
Default value: 256
Suggested values: 0, 128, 256, 512
Range of values: 0 <= Column <= 512
Minimum increment: 1
Recommended increment: 10

ScaleHeight (input_control)
extent.y -> real / integer
Vertical scale factor.
Default value: 0.5
Suggested values: 0.25, 0.5, 1.0, 1.0, 2.0, 3.0
Range of values: 0.001 <= ScaleHeight <= 10.0
Minimum increment: 0.001
Recommended increment: 0.1
Restriction: ScaleHeight > 0.0

ScaleWidth (input_control)
extent.x -> real / integer
Horizontal scale factor.
Default value: 0.5
Suggested values: 0.25, 0.5, 1.0, 1.0, 2.0, 3.0
Range of values: 0.001 <= ScaleWidth <= 10.0
Minimum increment: 0.001
Recommended increment: 0.1
Restriction: ScaleWidth > 0.0


Example
/* Reduction of an image (512 x 512 image points) by 50%: */
image_identity(:::) >
image_scale(::0.0,0.0,0.5,0.5:) >
image_transform__(Image:TrafoImage:1:).

Result

image_scale returns TRUE if all parameter values are correct. Otherwise, an exception is raised.


Possible Successors

image_transform__, image_rotate, image_translate


Alternatives

zoom_image1, zoom_image2



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