place sharpen filter before or after resize filter?

[nukesgoboom]

I have interlaced material from a dvd. i need to crop the letterbox out for maximum bittrate allocation and then resize to maintain aspect ratio.

i will crop, then deinterlace, but i like to apply a sharpen filter to counter-act the effects of the field blending of the de-interlacing. i am using Gunnar Thalin's area based de-interlacing filter.

should i apply the sharpen filter before or after the resize filter? i did some small tests with video game footage, and it seemed to look better if i placed the sharpen filter before the resize filter. is the correct?

[GodofaGap]

You want us to tell you what you prefered more?

[nukesgoboom]

i want to know which it should be.

de-interlacing should always go before resizing, but if i came in here and said resizing then de-interlacing looks better, then something would be wrong on my end. im just looking to see if the same rule applies to sharpen, resize.

[GodofaGap]

Resizing vertically before deinterlacing is conceptually wrong. After the resizing there is nothing left to deinterlace. I can't imagine anyone prefering this:

http://img528.imageshack.us/img528/6388/deinterlacedresizedwp1.th.jpg (http://img528.imageshack.us/my.php?image=deinterlacedresizedwp1.jpg)

http://img375.imageshack.us/img375/658/resizedeinterlacedbn3.th.jpg (http://img375.imageshack.us/my.php?image=resizedeinterlacedbn3.jpg)

It is obvious which one is better.

With sharpening before resizing, conceptually there is nothing wrong. One could argue that the other way around is faster, but you like what you like.

[nukesgoboom]

thanks for answering me. thats what i was looking for, 'conceptually there is nothing wrong'.

final note, about the resizing filter placement in virtualdub, should i as a rule ALWAYS place it last for safety? if i need to resize, and if i put it last, it will not interfere with the effects of the other filters like it does de-interlace as long as it comes last?

[GodofaGap]

Personally I prefer to the resizing directly after the deinterlacing and before other filtering. It is usually faster. Of course you cannot avoid a filter influencing the results of the filters that come after it. But usually it is not a worry.