User:Raffriff42/sandbox - Revision history

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2016-02-17T10:42:04Z

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Raffriff42: recopy avsforum post verbatim

2016-02-01T02:31:40Z

recopy avsforum post verbatim

Raffriff42: tweak

2016-02-01T02:21:00Z

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2016-02-01T01:51:40Z

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2016-02-01T01:47:44Z

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Raffriff42: b+2c=1

2016-02-01T01:42:01Z

b+2c=1

Raffriff42: typo

2016-02-01T01:35:59Z

typo

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2016-02-01T01:27:37Z

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Raffriff42: correction

2016-02-01T01:03:53Z

correction

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2016-02-01T00:58:57Z

tweak

@@ Line 149: / Line 149: @@
 <div {{ListItemContinue|2}} >
-''Note:'' the input argument named {{FuncArg|taps}} should really be called "lobes". When discussing resizers, "taps" has a different meaning, as described below (the first paragraph concerns <code>[[#LanczosResize|LanczosResize]](taps=2)</code>):
+''Note:'' the input argument named {{FuncArg|taps}} should really be called "lobes". When discussing resizers, "taps" has a different meaning, as described below:
 <div {{ListItemContinue|2}} >
-"For upsampling (making the image larger), the filter is sized such that the entire equation falls across 4 input samples, making it a 4-tap filter. It doesn't matter how big the output image is going to be - it's still just 4 taps. For downsampling (making the image smaller), the equation is sized so it will fall across 4 *destination* samples, which obviously are spaced at wider intervals than the source samples. So for downsampling by a factor of 2 (making the image half as big), the filter covers 2*4=8 input samples, and thus 8 taps. For 3x downsampling, you need 3*4=12 taps, and so forth.
+"So when people talk about Lanczos2, they mean a 2-lobe Lanczos-windowed sinc function. There are actually 4 lobes -- 2 on each side...
-Thus the total number of taps you need for downsampling is the downsampling ratio times the number of lobes (thus '''T'''x downsampling and Lanczos'''k'''Resize results in T*2*k taps). And practically, one needs to round that up to the next even integer. For upsampling, it's always 2*k taps." </div>
+"For upsampling (making the image larger), the filter is sized such that the entire equation falls across 4 input samples, making it a 4-tap filter. It doesn't matter how big the output image is going to be - it's still just 4 taps. For downsampling (making the image smaller), the equation is sized so it will fall across 4 *destination* samples, which obviously are spaced at wider intervals than the source samples. So for downsampling by a factor of 2 (making the image half as big), the filter covers 8 input samples, and thus 8 taps. For 3X downsampling, you need 12 taps, and so forth.
-Source: [http://www.avsforum.com/forum/26-home-theater-computers/460922-lanczos-vs-bicubic-comparison-2.html#post4760581 avsforum post] ([[lanczos lobs/taps|mirror]]).
 </div>
 </div>

@@ Line 2: / Line 2: @@
 ----
 <div style="max-width:62em" >
-Rescales the input video frames to an arbitrary new resolution, and optionally crops the frame before resizing with sub-pixel precision. There are trade-offs to be considered between retention of detail and introduction of new artifacts; this is why there are so many resizers in AviSynth.
+Scales the input video frames to an arbitrary new resolution, and optionally crops the frame before resizing with sub-pixel precision.
 </div>
 __TOC__
@@ Line 50: / Line 52: @@
 </div>
-<div {{ListItemContinue}} >
+*Note the cropping parameters are all [[Script_variables|floating point]]. This allows any '''Resize''' filter to be used as a sub-pixel shifter. <sup>[http://forum.doom9.org/showpost.php?p=938102&postcount=2]</sup>
-Note the edge semantics are slightly different. Also note that [[Crop]] gives a hard absolute boundary, and the Resizer filter lobes extend into the cropped region &ndash; but not beyond the physical edge of the image.
-As a general rule, use Crop to remove any hard borders or [[Wikipedia:VHS|VHS]] head switching noise; using the Resizer cropping may propagate the noise into the adjacent output pixels. Use the Resizer cropping to maintain accurate edge rendering when excising a part of a complete image.
+*Note that [[Crop]] gives a hard boundary, whereas the '''Resize''' filters interpolate pixels outside the cropped region &ndash; depending on the resizer kernel &ndash; bilinear, bicubic etc, and not beyond the edge of the image.
-Note the source cropping parameters are all [[Script_variables|floating point]]. This allows any resizer to be used as a sub-pixel shifter. <sup>[http://forum.doom9.org/showpost.php?p=938102&postcount=2]</sup>
+*As a general rule,
-</div>
+** [[Crop]] any hard borders or noise; '''Resize''' cropping may propagate the noise into the output.
 </div>
@@ Line 117: / Line 119: @@
 }}
-'''GaussResize''' uses a [[Wikipedia:Gaussian_filter|gaussian]] resizer, which does not overshoot &ndash; making it more accurate, but perhaps not as sharp to the eye.
+'''GaussResize''' uses a [[Wikipedia:Gaussian_filter|gaussian]] resizer, which unlike the bicubics, does not overshoot &ndash; but perhaps does not appear as sharp to the eye.
 ==== parameter ''p'' ====
@@ Line 186: / Line 188: @@
 }}
-'''Spline16Resize''', '''Spline36Resize''' and '''Spline64Resize''' are three [[Wikipedia:Spline_interpolation|Spline based]] resizers. They are the (cubic) spline based resizers from [http://sourceforge.net/projects/panotools/ Panorama tools] that fit a spline through the sample points and then derives the filter kernel from the resulting blending polynomials. See [http://forum.doom9.org/showthread.php?t=147117 this thread] for the details.
+'''Spline16Resize''', '''Spline36Resize''' and '''Spline64Resize''' are three [[Wikipedia:Spline_interpolation|Spline based]] resizers. They are the (cubic) spline based resizers from [http://sourceforge.net/projects/panotools/ Panorama tools] that fit a spline through the sample points and then derives the filter kernel from the resulting blending polynomials. See [http://forum.doom9.org/showthread.php?t=147117 this thread] for the technical details.
-The rationale for '''Spline''' is to be as sharp as possible with less ringing artifacts than [[#LanczosResize|LanczosResize]] produces. '''Spline16Resize''' uses <tt>sqrt(16)=4</tt> sample points, '''Spline36Resize''' uses 6 sample points, etc ... The more sample points used, the sharper your clip will get. Several resizer comparison pages are given in the [[#External Links|External Links]] section.
+*'''Spline64Resize''' is considered the most accurate filter for enlarging or reducing by moderate amounts (less than double/half).
 </div>

@@ Line 41: / Line 41: @@
 ...or more succinctly:
 </div>
-<div {{BoxWidthIndent|36|3}} >
+<div {{BoxWidthIndent|54|3}} >
   BilinearResize(100, 150, 10, 10, 200, 300)
 </div><div {{ListItemContinue}} >
 The operations are the same as if you put [[Crop]] before the Resize:
 </div>
-<div {{BoxWidthIndent|36|3}} >
+<div {{BoxWidthIndent|54|3}} >
   Crop(10, 10, 200, 300).BilinearResize(100, 150)
 </div>

@@ Line 24: / Line 24: @@
 * If &lt;= zero, they set the cropping of the '''right''' and '''bottom''' edges respectively,  before resizing.
 Note, there are certain limits:
-* {{FuncArg|clip}}.[[Clip_properties|Width]] must be &gt;= ({{FuncArg|src_left}} + {{FuncArg|src_width}})
+* {{FuncArg|clip}}.[[Clip_properties|Width]] must be &gt;= ({{FuncArg|src_left}} + '''width''')
 * {{FuncArg|clip}}.[[Clip_properties|Width]] must be &gt;&nbsp; ({{FuncArg|src_left}} + '''right''')
-* {{FuncArg|clip}}.[[Clip_properties|Height]] must be &gt;= ({{FuncArg|src_top}} + {{FuncArg|src_height}})
+* {{FuncArg|clip}}.[[Clip_properties|Height]] must be &gt;= ({{FuncArg|src_top}} + '''height''')
 * {{FuncArg|clip}}.[[Clip_properties|Height]] must be &gt;&nbsp; ({{FuncArg|src_top}} + '''bottom''')
 ...otherwise it would enlarge ("un-crop") the clip, or reduce width or height to 0, which is not allowed.

@@ Line 87: / Line 87: @@
 <div {{ListItemContinue|2}} >
-You have to set "{{FuncArg|b}} + 2.0 * {{FuncArg|c}} = 1.0" for the numerically most accurate filter. This gives for {{FuncArg|b}}=0 the maximum value of 0.5 for {{FuncArg|c}}, which is the [[Wikipedia:Cubic_Hermite_spline#Catmull.E2.80.93Rom_spline|Catmull-Rom spline]] and a good suggestion for sharpness.
+You have to set [{{FuncArg|b}} + 2{{FuncArg|c}} = 1] for the most numerically accurate filter. This gives for {{FuncArg|b}}=0 the maximum value of 0.5 for {{FuncArg|c}}, which is the [[Wikipedia:Cubic_Hermite_spline#Catmull.E2.80.93Rom_spline|Catmull-Rom spline]] and a good suggestion for sharpness.
 As {{FuncArg|c}} exceeds 0.6, the filter starts to [[Wikipedia:Ringing_artifacts|"ring"]] or overshoot. You won't get true sharpness &ndash; what you'll get is exaggerated edges.

@@ Line 23: / Line 23: @@
 * If &nbsp;&gt; zero, these set the '''width''' and '''height''' of the clip before resizing.
 * If &lt;= zero, they set the cropping of the '''right''' and '''bottom''' edges respectively,  before resizing.
-Note there are certain restrictions:
+Note, there are certain limits:
-* {{FuncArg|src_width}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}})
+* {{FuncArg|clip}}.[[Clip_properties|Width]] must be &gt;= ({{FuncArg|src_left}} + {{FuncArg|src_width}})
-* {{FuncArg|src_height}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}})
+* {{FuncArg|clip}}.[[Clip_properties|Width]] must be &gt;&nbsp; ({{FuncArg|src_left}} + '''right''')
-<div {{ListItemContinue}} >
+* {{FuncArg|clip}}.[[Clip_properties|Height]] must be &gt;= ({{FuncArg|src_top}} + {{FuncArg|src_height}})
-...this would "un-crop" the clip, which is not allowed.
+* {{FuncArg|clip}}.[[Clip_properties|Height]] must be &gt;&nbsp; ({{FuncArg|src_top}} + '''bottom''')
-</div>
+...otherwise it would enlarge ("un-crop") the clip, or reduce width or height to 0, which is not allowed.
-* '''-'''{{FuncArg|src_width}} ('''right''') cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}})
-* '''-'''{{FuncArg|src_height}} ('''bottom''') cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}})
-<div {{ListItemContinue}} >
-...this would reduce clip width or height to 0, which is not allowed.
 </div>
 </div>
@@ Line 191: / Line 187: @@
 }}
-'''Spline16Resize''', '''Spline36Resize''' and '''Spline64Resize''' are three [[Wikipedia:Spline_interpolation|Spline based]] resizers. They are the (cubic) spline based resizers from [https://sourceforge.net/projects/panotools/ Panorama tools] that fit a spline through the sample points and then derives the filter kernel from the resulting blending polynomials. See [http://forum.doom9.org/showthread.php?t=147117 this thread] for the details.
+'''Spline16Resize''', '''Spline36Resize''' and '''Spline64Resize''' are three [[Wikipedia:Spline_interpolation|Spline based]] resizers. They are the (cubic) spline based resizers from [http://sourceforge.net/projects/panotools/ Panorama tools] that fit a spline through the sample points and then derives the filter kernel from the resulting blending polynomials. See [http://forum.doom9.org/showthread.php?t=147117 this thread] for the details.
 The rationale for '''Spline''' is to be as sharp as possible with less ringing artifacts than [[#LanczosResize|LanczosResize]] produces. '''Spline16Resize''' uses <tt>sqrt(16)=4</tt> sample points, '''Spline36Resize''' uses 6 sample points, etc ... The more sample points used, the sharper your clip will get. Several resizer comparison pages are given in the [[#External Links|External Links]] section.
@@ Line 256: / Line 252: @@
 * [http://jeanbruenn.info/2011/10/30/upscaling-in-avisynth-comparison-of-resizers/ ''Upscaling in Avisynth – Comparison of resizers''] | [http://web.archive.org/web/20140207171106/http://jeanbruenn.info/2011/10/30/upscaling-in-avisynth-comparison-of-resizers/ archived link]
 * [http://web.archive.org/web/20060827184031/http://www.path.unimelb.edu.au/~dersch/interpolator/interpolator.html ''Testing Interpolator Quality''] (Helmut Dersch, Technical University Furtwangen)
-* [https://forum.doom9.org/showthread.php?t=172871 Doom9 discussion of resizers for downsizing]
+* [http://forum.doom9.org/showthread.php?t=172871 Doom9 discussion of resizers for downsizing]
 == Changelog ==
 . . .

@@ Line 18: / Line 18: @@
 {{Par2|src_width, src_height|int|(source width, height)}}
 <div {{ListItemContinue|2}} >
-{| border="0" style="width:52em"
+As with [[Crop]], these arguments have different functionality, depending on their value:
-|colspan="4"| See [[#Cropping |cropping]] discussion below.
+* If &nbsp;&gt; zero, these set the '''width''' and '''height''' of the clip before resizing.
-|-
+* If &lt;= zero, they set the cropping of the '''right''' and '''bottom''' edges respectively,  before resizing.
-|colspan="4"| As with [[Crop]], these arguments have different functionality, depending on their value:
+Note there are certain restrictions:
-|-
+* {{FuncArg|src_width}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}})
-|colspan="4"| {{BoldColor|#638C9C|100|&bull;}} If &nbsp;&gt; zero, these set the '''width''' and '''height''' of the clip before resizing.
+* {{FuncArg|src_height}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}})
-|-
+<div {{ListItemContinue}} >
-|colspan="4"| {{BoldColor|#638C9C|100|&bull;}} If &lt;= zero, they set the cropping of the '''right''' and '''bottom''' edges respectively,  before resizing.
+...this would "un-crop" the clip, which is not allowed.
-|-
+</div>
-|colspan="4"| Note there are certain restrictions:
+* '''-'''{{FuncArg|src_right}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}})
-|-
+* '''-'''{{FuncArg|src_bottom}} cannot be &gt;= ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}})
-| {{BoldColor|#638C9C|100|&bull;}} {{FuncArg|src_width}}
+<div {{ListItemContinue}} >
-| cannot be &gt;=&nbsp;
+...this would reduce clip width or height to 0, which is not allowed.
-| ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}});
+</div>
-| &nbsp;this would "un-crop" the clip, which is not allowed.
-|-
-| {{BoldColor|#638C9C|100|&bull;}} {{FuncArg|src_height}}
-| cannot be &gt;=
-| ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}});
-| &nbsp;this would "un-crop" the clip, which is not allowed.
-|-
-| {{BoldColor|#638C9C|100|&bull;}} '''-'''{{FuncArg|src_right}}
-| cannot be &gt;=
-| ({{FuncArg|clip}}.[[Clip_properties|Width]] - {{FuncArg|src_left}});
-| &nbsp;this would reduce clip width to 0, which is not allowed.
-|-
-| {{BoldColor|#638C9C|100|&bull;}} '''-'''{{FuncArg|src_bottom}}
-| cannot be &gt;=
-| ({{FuncArg|clip}}.[[Clip_properties|Height]] - {{FuncArg|src_top}});
-| &nbsp;this would reduce clip height to 0, which is not allowed.
-|}
 </div>