zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor (Operator)

Name

zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor — Zoom an image by a given factor.

Signature

Description

zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor scales the image ImageImageImageimageimage by a factor of ScaleWidthScaleWidthScaleWidthscaleWidthscale_width in width and a factor ScaleHeightScaleHeightScaleHeightscaleHeightscale_height in height. The parameter InterpolationInterpolationInterpolationinterpolationinterpolation determines the type of interpolation used (see affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image). The domain of the input image is ignored, i.e., assumed to be the full rectangle of the image.

Attention

If the system parameter 'int_zooming'"int_zooming""int_zooming""int_zooming""int_zooming" is set to 'true'"true""true""true""true", the internally used integer arithmetic may lead to errors in the following three cases: First, if zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor is used on an uint2 or int2 image with high dynamics (i.e. images containing values close to the respective limits) in combination with scale factors smaller than 0.5, then the gray values of the output image may be erroneous. Second, if InterpolationInterpolationInterpolationinterpolationinterpolation is set to a value other than 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor", a large scale factor is applied, and a large output image is obtained, then undefined gray values at the lower and at the right image border may result. The maximum width of this border of undefined gray values can be estimated as , where S is the scale factor in one dimension and I is the size of the output image in the corresponding dimension. Third, for real images undefined gray values can occur on all image borders, if InterpolationInterpolationInterpolationinterpolationinterpolation is set to 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor", and if both the input and output image is large. In all cases, it is recommended to set 'int_zooming'"int_zooming""int_zooming""int_zooming""int_zooming" to 'false'"false""false""false""false" via the operator set_systemset_systemSetSystemSetSystemset_system.

If 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor" is set as interpolation method the results can differ slightly for different image types. This is due to the usage of image type specific optimizations of the applied interpolation algorithm.

zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor is not parallelized internally if ScaleWidthScaleWidthScaleWidthscaleWidthscale_width = 0.5 and ScaleHeightScaleHeightScaleHeightscaleHeightscale_height = 0.5. Further zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor is not parallelized internally with InterpolationInterpolationInterpolationinterpolationinterpolation='nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor".

zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor can be executed on OpenCL devices if the input image does not exceed the maximum size of image objects of the selected device. Due to numerical reasons, there can be slight differences in the output compared to the execution on the CPU.

Execution Information

• Supports OpenCL compute devices.
• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.
• Automatically parallelized on channel level.
• Automatically parallelized on internal data level.

Parameters

read_image(Image,'monkey')
dev_display (Image)
zoom_image_factor (Image, ZoomImage, 0.25, 0.25, 'constant')
dev_display (ZoomImage)

read_image(&Image,"monkey");
disp_image(Image,WindowHandle);
zoom_image_factor(Image,&ZooImage,0.25,0.25,"constant");
disp_image(ZooImage,WindowHandle);

read_image(Image,'monkey')
dev_display (Image)
zoom_image_factor (Image, ZoomImage, 0.25, 0.25, 'constant')
dev_display (ZoomImage)

read_image(Image,'monkey')
dev_display (Image)
zoom_image_factor (Image, ZoomImage, 0.25, 0.25, 'constant')
dev_display (ZoomImage)

Alternatives

zoom_image_sizezoom_image_sizeZoomImageSizeZoomImageSizezoom_image_size, affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image, hom_mat2d_scalehom_mat2d_scaleHomMat2dScaleHomMat2dScalehom_mat2d_scale

See also

hom_mat2d_scalehom_mat2d_scaleHomMat2dScaleHomMat2dScalehom_mat2d_scale, affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image

Module

Foundation