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by NicolasRobidoux
2014-06-08T10:41:28-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Side note: It is my current opinion that the sharpest Keys cubic that's usable for general natural image EWA upsampling is the Robidoux one. IMO, it's actually a nudge too sharp. Consequently, I don't recommend EWA Mitchell, RobidouxSharp, and Catmull-Rom for upsampling. And I actually don't really ...
by NicolasRobidoux
2014-06-08T10:09:31-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

I persists in thinking that if you vary B and C (without, possibly, sticking to Keys cubics) you'll find a combination that compares. The only thing that could make a comparable result reachable with 4x is that you extend your disc up to radius 2.5. The problem with this is: the second function fro...
by NicolasRobidoux
2014-06-08T09:55:56-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

If any reader has any comment regarding the look of the RobidouxSoft result, I'd like to read it.
Also, if Sergio could post the result with EWA Robidoux, I'd be thankful.
by NicolasRobidoux
2014-06-08T09:50:27-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Sergio: I wish I could tell you what B,C combination would give you something that complies to the look that I guess you are after. However, this look appears to be fairly far from what I have been trying to achieve, and consequently it is likely to be far from Keys cubics. I actually like the resul...
by NicolasRobidoux
2014-06-08T09:16:02-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

I persists in thinking that if you vary B and C (without, possibly, sticking to Keys cubics) you'll find a combination that compares.
The only thing that could make a comparable result reachable (correction: UNreachable) with 4x is that you extend your disc up to radius 2.5.
by NicolasRobidoux
2014-06-08T08:53:33-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Don't give up too fast.
Let's first try Keys cubics: Once you choose B, set C=(1-B)/2.
Start with Mitchell which is the Keys with B = 1/3.
Then, vary B until you're happy with what you get.
by NicolasRobidoux
2014-06-08T08:34:51-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

EWA Catmull-Rom is super jaggy. Some people have liked it for downsampling but I've never liked it, up or down.
Try EWA RobidouxSoft:

Code: Select all

B = (9-3*sqrt(2))/7 = 0.67962275898295921
C = (1-B)/2 = 0.1601886205085204
by NicolasRobidoux
2014-06-08T08:04:57-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

A question for you: that jinc2 filter I made, technically, should I call it ewa-lanczos2sharp? It's not really what I call EWA Lanczos2Sharp because it does not use Jinc and it does not use one of my standard deblurs. It's a deblurred EWA Sinc-windowed Sinc 2-lobe. <- Too long for a short name. So ...
by NicolasRobidoux
2014-06-08T08:00:58-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Sounds like you're running out of "registers". "Red-black" tricks (this includes my initial suggestion about min and max being computed as min(min(.,.),min(.,.)) instead of min(.,min(.,min(.,.))) ) generally use more memory. If it's not too much to ask, could you try kolor = mul(weights[0], float4x3...
by NicolasRobidoux
2014-06-08T04:10:48-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

One last "manic perfectionist" thing: Some of the positions, you know ahead of time that they are within 1, or farther than 1. So, you could use a special weight function for these special cases and skip some branches for these "indexes". What I mean is this: I assume that you fix things so that th...
by NicolasRobidoux
2014-06-08T00:52:10-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Hyllian wrote:It saved me like 20% of processing time! Indeed it works! Thanks.
Standard polynomial evaluation trick: Horner's rule.
by NicolasRobidoux
2014-06-07T13:53:22-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

You write beautifully clear code.
by NicolasRobidoux
2014-06-07T13:52:27-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

One last "manic perfectionist" thing: Some of the positions, you know ahead of time that they are within 1, or farther than 1. So, you could use a special weight function for these special cases and skip some branches for these "indexes".
by NicolasRobidoux
2014-06-07T13:44:55-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

If you have set things up so that the alignment is the same throughout the computation, a number of the 16 texels are outside of the discs and consequently always have coefficient 0, which means they can be dropped. (Maybe this requires reflections of the data to put it in "standard position"---like...
by NicolasRobidoux
2014-06-07T13:38:15-07:00
Forum: Users
Topic: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling
Replies: 134
Views: 172759

Re: Sigmoidized Ginseng (pronounced "Jinc-Sinc") resampling

Suggestion: Compute the weights using the formulas used in ImageMagick's resize.c if (x < 1.0) return(resize_filter->coefficient[0]+x*(x*(resize_filter->coefficient[1]+x*resize_filter->coefficient[2]))); if (x < 2.0) return(resize_filter->coefficient[3]+x*(resize_filter->coefficient[4]+x*(resize_fil...