projective_trans_image_sizeT_projective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSize (Operator)

Name

projective_trans_image_sizeT_projective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSize — Apply a projective transformation to an image and specify the output image size.

Signature

projective_trans_image_size(Image : TransImage : HomMat2D, Interpolation, Width, Height, TransformDomain : )

projective_trans_image_sizeprojective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSizeProjectiveTransImageSize applies the projective transformation (homography) determined by the homogeneous transformation matrix HomMat2DHomMat2DHomMat2DHomMat2DhomMat2D on the input image ImageImageImageImageimage and stores the result into the output image TransImageTransImageTransImageTransImagetransImage.

TransImageTransImageTransImageTransImagetransImage will be clipped at the output dimensions HeightHeightHeightHeightheightxWidthWidthWidthWidthwidth. Apart from this, projective_trans_image_sizeprojective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSizeProjectiveTransImageSize is identical to its alternative version projective_trans_imageprojective_trans_imageProjectiveTransImageProjectiveTransImageProjectiveTransImage.

Attention

The used coordinate system is the same as in affine_trans_pixelaffine_trans_pixelAffineTransPixelAffineTransPixelAffineTransPixel. This means that in fact not HomMat2DHomMat2DHomMat2DHomMat2DhomMat2D is applied but a modified version. Therefore, applying projective_trans_image_sizeprojective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSizeProjectiveTransImageSize corresponds to the following chain of transformations, which is applied to each point (Row_i, Col_i) of the image (input and output pixels as homogeneous vectors):

As an effect, you might get unexpected results when creating projective transformations based on coordinates that are derived from the image, e.g., by operators like area_center_grayarea_center_grayAreaCenterGrayAreaCenterGrayAreaCenterGray. For example, if you use this operator to calculate the center of gravity of a rotationally symmetric image and then rotate the image around this point using hom_mat2d_rotatehom_mat2d_rotateHomMat2dRotateHomMat2dRotateHomMat2dRotate, the resulting image will not lie on the original one. In such a case, you can compensate this effect by applying the following translations to HomMat2DHomMat2DHomMat2DHomMat2DhomMat2D before using it in projective_trans_image_sizeprojective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSizeProjectiveTransImageSize:

  hom_mat2d_translate(HomMat2D, 0.5, 0.5, HomMat2DTmp)
  hom_mat2d_translate_local(HomMat2DTmp, -0.5, -0.5, HomMat2DAdapted)
  projective_trans_image_size(Image, TransImage, HomMat2DAdapted,
	               'bilinear', Width, Height, 'false')

For an explanation of the different 2D coordinate systems used in HALCON, see the introduction of chapter Transformations / 2D Transformations.

projective_trans_image_sizeprojective_trans_image_sizeProjectiveTransImageSizeProjectiveTransImageSizeProjectiveTransImageSize can be executed on OpenCL devices if the input image does not exceed the maximum size of image objects of the selected device and the parameter TransformDomainTransformDomainTransformDomainTransformDomaintransformDomain is set to 'false'"false""false""false""false". The result can diverge slightly from that calculated 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

ImageImageImageImageimage (input_object) (multichannel-)image(-array) → object (byte* / uint2* / real*) *allowed for compute devices

Input image.

TransImageTransImageTransImageTransImagetransImage (output_object) (multichannel-)image(-array) → object (byte / uint2 / real)

Output image.

HomMat2DHomMat2DHomMat2DHomMat2DhomMat2D (input_control) hom_mat2d → (real)

Homogeneous projective transformation matrix.

InterpolationInterpolationInterpolationInterpolationinterpolation (input_control) string → (string)

Interpolation method for the transformation.

Default value: 'bilinear' "bilinear" "bilinear" "bilinear" "bilinear"

List of values: 'bilinear'"bilinear""bilinear""bilinear""bilinear", 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor"