Legacy ImageMagick Discussions Archive

Anyways, Nicolas, thank you very much for the suggestions, they were very useful! I woudn't have realized how bland the textures were in my first batch of pictures if you hadn't pointed! It's very good to get other perspectives and broad your own.

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. Sure, this is using Robidoux params: http://s12.postimg.org/qohfc7aih/clown_2xcc_2x4x.jpg How can I describe the quality I'm lo...

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...

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. No dice! There isn't a single Keys config that comes close to this ewa-lanczos (WA=0.4, WB=0.9) quality: http...

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: B = (9-3*sqrt(2))/7 = 0.67962275898295921 C = (1-B)/2 = 0.1601886205085204 Very soft, indeed. A bit too blurry: http://s21.postimg.org/cc23437oj/clown_2xcc_2x4x.jpg ...

If it's not too much to ask, could you try kolor = mul(weights[0], float4x3(c00, c10, c20, c30)); color = mul(weights[1], float4x3(c01, c11, c21, c31)); kolor += mul(weights[2], float4x3(c02, c12, c22, c32)); color += mul(weights[3], float4x3(c03, c13, c23, c33)); color += kolor ? Sure, but no gain...

Nicolas, for some reason, your last optimization trick actually made the code slower (119 vs 129 cycles), measured using nvshaderperf. OTOH, the Horner's rule one was very good (119 vs 143 cycles). Maybe my Cg compiler is smart for some of these tricks already, and dumb for others. A question for yo...

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_fi...

I finished implementing an EWA-cubic shader: http://pastebin.com/Csfi4nmr I need to tweak its parameters to see how the output change. I only can test it with games, as it's in a format only Retroarch emulator recognizes. I'll take a rest now and when I have some good params, I'll post here some scr...

You using weights[4*(j+1)+k+1] = sinc(WA*dist(j-0.25, k-0.25))*sinc(WB*dist(j-0.25, k-0.25)); with WA non-integer is an example of "deblurring". My own EWA LanczosSharp is an example of "deblurring" as well. In general, it means not sticking to the scaling of the filter kernel s...

Nice to see the idea of "deblurring" kernels instead of using them "straight up" (which of course was in IM way before I got involved, but was not used much I think) exploited to good effect. As some of you know, I've been pushing the idea that there are "special" debl...

Thanks for the tips, Nicolas. I'll look into it later.

If I have news, I'll post here.

Ok, I was just making an observation about pixel art. I've already developed an algorithm for that kind of image. In this thread I'm more interested in extract the most of a Jinc2 algorithm, because for realtime applications as games, Jinc3 is a bit prohibitive yet. Actually, this Jinc2 implementati...

Thanks, Nicolas, for the suggestions. I've implemented the blend suggestion and it indeed worked better for natural images. Though for Pixel Art (my primary need) it isn't so good, because it let escape some ringing. Here's the images using the blend AR: http://s15.postimg.org/van8iuwiv/car_show_2xj...

The anti-ringing works more or less like this: It gets the four nearest neighbors from the point I'm sampling and choose the max and the min, per color channel. Then, the jinc2 output is clamped to that range (min,max). By toning down, do you mean enlarging that range? Something like a new range (mi...