[Scipy-tickets] [SciPy] #515: ndimage.zoom introduces artefacts at right and bottom edges

SciPy scipy-tickets@scipy....
Tue Oct 16 22:47:41 CDT 2007


#515: ndimage.zoom introduces artefacts at right and bottom edges
---------------------------+------------------------------------------------
 Reporter:  0ion9          |       Owner:  somebody
     Type:  defect         |      Status:  new     
 Priority:  normal         |   Milestone:  0.7     
Component:  scipy.ndimage  |     Version:  devel   
 Severity:  normal         |    Keywords:          
---------------------------+------------------------------------------------
 .. when zoom factor approaches or exceeds 2.0.
 Paste the following code into a new file and run it to see the bug.



 {{{
 import numpy
 arr = numpy.array (range (25))
 arr.shape = (5,5)
 import scipy.ndimage as sn
 result = sn.zoom (arr, 2.0)
 print (result)



 #
 # Produces the following output:
 # (note the erroneous line of zeros along R + B edge;
 #  instead of this output, the input should be stretched to fully
 #  fit the output size requested.)
 #
 #array([[ 0,  0,  1,  2,  2,  2,  3,  4,  4,  0],
 #       [ 2,  2,  3,  3,  4,  4,  5,  5,  6,  0],
 #       [ 5,  5,  6,  7,  7,  7,  8,  9,  9,  0],
 #       [ 8,  8,  9,  9, 10, 10, 11, 11, 12,  0],
 #       [10, 10, 11, 12, 12, 12, 13, 14, 14,  0],
 #       [12, 13, 13, 14, 14, 15, 15, 16, 16,  0],
 #       [15, 15, 16, 17, 17, 17, 18, 19, 19,  0],
 #       [18, 19, 19, 20, 20, 21, 21, 22, 22,  0],
 #       [20, 20, 21, 22, 22, 22, 23, 24, 24,  0],
 #       [ 0,  0,  0,  0,  0,  0,  0,  0,  0,  0]])
 }}}




 Also, if you try running the following lines, you will see it causes an
 exception
 (apparently the output array, shape = (10,10) is not of the correct shape!
 But the output of sn.zoom (arr, 2.0) *is* 10x10 in size!)

 {{{
 output = numpy.zeros (shape = (10,10), dtype = numpy.uint8)
 sn.zoom (arr, 2.0, output = output)
 }}}

-- 
Ticket URL: <http://scipy.org/scipy/scipy/ticket/515>
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