View source for Tcanny

{{FilterCat4|External_filters|Plugins|Other_filters|Edge_detection}}
{{Filter3
| {{Author/tritical}}
| v1.0
|[http://web.archive.org/web/20140804144614/http://bengal.missouri.edu/~kes25c/tcanny.zip tcanny.zip]
| Edge Detection 
| [http://www.gnu.org/licenses/gpl-2.0.txt GPLv2]
|}}

== Description ==
<tt>tcanny</tt> contains a Canny edge detection filter and distance transform filter.<br>
<br>

== Requirements ==
* AviSynth 2.5.8 or [http://forum.doom9.org/showthread.php?t=168764 greater]
* Supported color formats: [[YUY2]], [[YV12]]
<br>
== [[Script variables|Syntax and Parameters]] ==
<br>
=== tcanny ===
Builds an edge map using Canny edge detection.
<br>
<br>
:{{Template:FuncDef|tcanny(clip, float "sigma", float "t_h", float "t_l", int "nms", int "mode", int "plane", float "gmmax")}}
<br>
::{{Par2| |clip| }}
:::Input clip; only YUY2 and YV12 are supported.
<br>
::{{Par2|sigma|float|1.5}}
:::Standard deviation of Gaussian blur. 0 means no blurring before edge detection.
<br>
::{{Par2|t_h|float|8.0}}
:::High gradient magnitude threshold for hysteresis.
<br>
::{{Par2|t_l|float|1.0}}
:::Low gradient magnitude threshold for hysteresis.
<br>
::{{Par2|nms|int|3}}
:::Byte mask choosing non-maxima suppression method(s).

::::If (nms&1) - if pixel is maxima along nearest integer direction then keep.
::::If (nms&3) - if pixel is maxima along linearly interpolated direction then keep.
<br>
::{{Par2|mode|int|0}}
:::Sets the output format:

::::*0 : thresholded edge map (255 for edge, 0 for non-edge)
::::*1 : gradient magnitude map. Scaled to 0-255 range based on {{Template:FuncDef3|gmmax}}.
::::::pixel_val = min(grad_mag*255/{{Template:FuncDef3|gmmax}},255)
::::*2 : edge pixel only gradient direction map (non-edge pixels set to 0)
::::*3 : gradient direction map
<blockquote style="width: 50%;">
<pre>
            Gradient direction maps discretize [0-180) degree range into 256 bins.

                 0 = [000.000-000.351}
                 1 = [000.351-001.054)
                 .
                 .
                 .
               255 = [179.648-180.000)

                        135   90  45
                           \  |  /
                       180 --   -- 0
                            / |  \
                          45  90  135

                * This is the gradient direction, so the line direction 
                  is orthogonal to it (90 degree rotation). It only goes 
                  through 180 because for this case:

                     180+n = n, 0 <= n < 180</pre></blockquote>
<br>
::{{Par2|plane|int|1}}
:::Byte mask indicating which planes to process. If a plane isn't processed then it is copied through as is.

::::if (plane&1) - process Y
::::if (plane&2) - process U
::::if (plane&4) - process V
<br>
::{{Par2|gmmax|float|50.0}}
:::Used for scaling gradient magnitude into [0,255] for {{Template:FuncDef3|mode}}=1.
:::{{Template:FuncDef3|gmmax}} is internally set to 1.0 if you set it to < 1.0.
<br>
-------------
<br>
=== tdtrans ===
Performs a distance transformation on an edge map. This filter assumes the input image is 0 for non-edge pixels, and > 0 for edge pixels.<br>
The distance transform sets each pixel equal to the distance from it to the nearest edge pixel.
<br>
<br>
:{{Template:FuncDef|tdtrans (clip, int "mode", int "plane")}}
<br>
::{{Par2| |clip| }}
:::Input clip; only YUY2 and YV12 are supported.
<br>
::{{Par2|mode|int|1}}
:::Sets distance type.

::::*0 - city block
::::*1 - euclidean

::::: * For the euclidean case the distance is rounded to the nearest integer.
::::: * For both cases distances greater than 255 are set to 255.
<br>
::{{Par2|plane|int|1}}
:::Byte mask indicating which planes to process. Same as in {{Template:FuncDef3|tcanny}}.
<br>

== Examples == 
{{Template:FuncDef3|tcanny}} with default settings:
 [[AviSource]]("blah.avi")
 TCannyMod(sigma=1.5, t_h=8.0, t_l=1.0, nms=3, mode=0, plane=1, gmmax=50.0)
<br>
{{Template:FuncDef3|tdtrans }} with default settings:
 [[AviSource]]("blah.avi")
 tdtrans(mode=1, plane=1)
<br>

== Changelog ==
 Version      Date            Changes<br>
 v1.0         06/03/2009      - Initial release
<br>

== Archived Downloads ==
{| class="wikitable" border="1"; width="600px"
|-
!!width="100px"| Version
!!width="150px"| Download
!!width="150px"| Mirror
|-
!v1.0
|<strike>[http://bengal.missouri.edu/~kes25c/tcanny.zip tcanny.zip]</strike>
|[http://web.archive.org/web/20140804144614/http://bengal.missouri.edu/~kes25c/tcanny.zip tcanny.zip]
|}
<br>

== External Links ==
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<br>
-----------------------------------------------
'''Back to [[External_filters#Edge_Detection|External Filters]] &larr;'''