Bug or feature: differences between crop before resize and crop in resize function - Page 2

Gavino · 3rd March 2012, 17:20

It's not a question of 'educating' Crop.
As others have tried to explain, chroma is subsampled in YV12.
This means that in a 720x576 clip, there are only 360x288 chroma pixels.
You cannot crop at odd numbers, as there is no chroma pixel at those points.

$in0bi · 3rd March 2012, 18:39

So how and why Resize can do it or you want to say that Resizecrop can't do it? If the second I showed the example in my previous post.

Didée · 3rd March 2012, 19:17

Crop simply does a hard cut-off. (And therefore is limited by subsampled chroma pixel structure.)
No kind of interpolation is happening here.

Resize-crop does interpolation, taking the "outer" pixels into consideration.

The operations are very well laid out in what they are doing. If any sort of "education" is needed, then it's not for the filters, but for the user.

Gavino · 3rd March 2012, 19:18

Resize can do it because it does resampling - that's what resizers do.
Crop simply removes some of the existing pixels and leaves the remainder untouched.

gyth · 3rd March 2012, 23:11

You can crop by odd amounts in yv24, which is available in avisynth 2.6a3

3rd March 2012, 17:20	#21 \| Link
Gavino Avisynth language lover Join Date: Dec 2007 Location: Spain Posts: 3,431	It's not a question of 'educating' Crop. As others have tried to explain, chroma is subsampled in YV12. This means that in a 720x576 clip, there are only 360x288 chroma pixels. You cannot crop at odd numbers, as there is no chroma pixel at those points. __________________ GScript and GRunT - complex Avisynth scripting made easier

3rd March 2012, 19:17	#23 \| Link
Didée Registered User Join Date: Apr 2002 Location: Germany Posts: 5,391	Crop simply does a hard cut-off. (And therefore is limited by subsampled chroma pixel structure.) No kind of interpolation is happening here. Resize-crop does interpolation, taking the "outer" pixels into consideration. The operations are very well laid out in what they are doing. If any sort of "education" is needed, then it's not for the filters, but for the user. __________________ - We´re at the beginning of the end of mankind´s childhood - My little flickr gallery. (Yes indeed, I do have hobbies other than digital video!)

3rd March 2012, 19:18	#24 \| Link
Gavino Avisynth language lover Join Date: Dec 2007 Location: Spain Posts: 3,431	Resize can do it because it does resampling - that's what resizers do. Crop simply removes some of the existing pixels and leaves the remainder untouched. __________________ GScript and GRunT - complex Avisynth scripting made easier

3rd March 2012, 18:39	#22 \| Link
$in0bi Registered User Join Date: Oct 2011 Posts: 11	So how and why Resize can do it or you want to say that Resizecrop can't do it? If the second I showed the example in my previous post.

3rd March 2012, 23:11	#25 \| Link
gyth Registered User Join Date: Sep 2011 Posts: 86	You can crop by odd amounts in yv24, which is available in avisynth 2.6a3