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annotate main/image/inst/findbounds.m @ 11670:0f16ee5611b8 octave-forge
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
| author | carandraug |
|---|---|
| date | Mon, 29 Apr 2013 12:53:23 +0000 |
| parents | fbd81057dab0 |
| children |
| rev | line source |
|---|---|
| 11662 | 1 ## Copyright (C) 2012 Pantxo Diribarne |
| 2 ## | |
| 3 ## This program is free software; you can redistribute it and/or modify | |
| 4 ## it under the terms of the GNU General Public License as published by | |
| 5 ## the Free Software Foundation; either version 3 of the License, or | |
| 6 ## (at your option) any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, | |
| 9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 11 ## GNU General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with Octave; see the file COPYING. If not, see | |
| 15 ## <http://www.gnu.org/licenses/>. | |
| 16 | |
| 17 ## -*- texinfo -*- | |
| 18 ## @deftypefn {Function File} {@var{outbnd} =} findbounds (@var{T}, @var{inbnd}) | |
| 19 ## Estimate bounds for spatial transformation. | |
| 20 ## | |
| 21 ## Given a transformation structure @var{T} (see e.g. maketform) | |
| 22 ## and bounds @var{inbnd} (2-by-ndims_in) in an input space, returns | |
| 23 ## an estimation of the bounds in the output space @var{outbnd} | |
| 24 ## (2-by-ndims_out). For instance two dimensionnal bounds could | |
| 25 ## be represented as : [xmin ymin; xmax ymax]. If @var{T} does not | |
| 26 ## define a forward trasform (i.e. for 'polynomial'), the output | |
| 27 ## bounds are infered using fsolve and the inverse transform. | |
| 28 ## | |
| 29 ## @seealso{maketform, cp2tform, tformfwd} | |
| 30 ## @end deftypefn | |
| 31 | |
| 32 ## Author: Pantxo Diribarne <pantxo@dibona> | |
| 33 | |
| 34 function [outbnd] = findbounds (T, inbnd) | |
| 35 if (nargin != 2) | |
| 36 print_usage (); | |
| 37 elseif (! istform (T)) | |
| 38 error ("imtransform: T must be a transformation structure (see `maketform')"); | |
| 39 elseif (! all (size (inbnd) == [2 T.ndims_in])) | |
| 40 error ("imtransform: INBDN must have same size as T.ndims_in"); | |
| 41 endif | |
| 42 | |
| 43 ## Control points grid | |
| 44 if (columns (inbnd) == 2) | |
| 45 [xcp, ycp] = meshgrid (linspace (inbnd(1,1), inbnd(2,1), 3), | |
| 46 linspace (inbnd(1,2), inbnd(2,2), 3)); | |
| 47 xcp = reshape (xcp, numel (xcp), 1); | |
| 48 ycp = reshape (ycp, numel (ycp), 1); | |
| 49 xycp = [xcp, ycp]; | |
| 50 else | |
| 51 error ("findbounds: support only 2D inputbounds."); | |
| 52 endif | |
| 53 | |
| 54 ## Output bounds | |
| 55 if (!is_function_handle (T.forward_fcn)) | |
| 56 outbnd = zeros (size (xycp)); | |
| 57 for ii = 1:rows (xycp) | |
| 58 fun = @(x) tforminv (T, x) - xycp(ii,:); | |
| 59 outbnd(ii,:) = fsolve (fun, xycp(ii,:)); | |
| 60 endfor | |
| 61 else | |
| 62 outbnd = tformfwd (T, xycp); | |
| 63 endif | |
| 64 outbnd = [min(outbnd); max(outbnd)]; | |
| 65 endfunction | |
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11670
0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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66 |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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67 %!test |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
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68 %! im = checkerboard (); |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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69 %! theta = pi/6; |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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70 %! T = maketform ('affine', [cos(theta) -sin(theta); ... |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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71 %! sin(theta) cos(theta); 0 0]); |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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72 %! inbnd = [0 0; 1 1]; |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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73 %! outbnd = findbounds (T, inbnd); |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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74 %! diag = 2^.5; |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
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75 %! ang = pi/4; |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
|
76 %! assert (diff (outbnd(:,1)), diag * abs (cos (theta - ang)), eps) |
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0f16ee5611b8
image: add tests to findbounds and imtransform. Patch by Pantxo Diribarne <pantxo@dibona>
carandraug
parents:
11662
diff
changeset
|
77 %! assert (diff (outbnd(:,2)), diag * abs (cos (theta - ang)), eps) |