G'MIC

Reply to On the road to 1.5.6.0

nobody@flickr.com (otto06217) — Wed, 22 May 2013 14:33:20 -0700

otto06217 posted a reply:

Please tell me when you're ready.

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (RyanBram) — Wed, 22 May 2013 10:22:37 -0700

RyanBram posted a reply:

jayprich:
have you seen this algorithm www.google.com/search?q=kopf+lischinski , antimatter15's website referred to it

Yeah, I have seen it several times and very excited with it. Unfortunately, so far there is only theory without real implementation. Just some screenshot or comparison. No source code, no application. Just theory. But if someone can implement this algorithm in real image manipulation program, I will be more than happy.

Currently, xBR algorithm is the only notable rival for Koph-Lischinski. You can see there are no comparison between xBR and Koph-Lischinski in its main site. Because xBR is also new when Koph-Lischinski has invented. The main advantage of xBR is it has NoBlend feature which doesn't produce additional color for upscaled image that means the original image and the upscaled image still has similar number of unique colors. Because there is no additional color, therefore the image can be upscaled multiple times without visually loss of its quality. (See above image).

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (jayprich) — Wed, 22 May 2013 08:56:25 -0700

jayprich posted a reply:

have you seen this algorithm www.google.com/search?q=kopf+lischinski , antimatter15's website referred to it

Reply to New filter for 2x scaling

nobody@flickr.com (garagecoder) — Wed, 22 May 2013 04:39:49 -0700

garagecoder posted a reply:

Just as a side experiment I tried using resize in grid mode and inpaint_flow to fill in the gaps, it actually gives quite respectable results and you can adjust the settings of inpaint easily. Only drawback is it's a tad slow compared to other methods. For some reason I couldn't use -repair in the same manner but I suppose it must have limits on the area size.

-+[0] 0.2
-r2dx {w*2},4
--select_color 0,0,0,0
-rv -inpaint_flow 4,4,4,1,1
-rm[0]

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (RyanBram) — Tue, 21 May 2013 17:18:08 -0700

RyanBram posted a reply:

Ronounours:
HQX looks really interesting indeed.

Yeah Hqx looks interesting, but now there is a new algorithm called xBR that is superior than Hqx. You can see again above image to see the comparison. xBR can maintain image sharpness while Hqx will blurs it. xBR also have NoBlend feature which doesn't add additional colors to image so the image can be upscaled multiple times without visually loss of its quality. Download xBR mario image above and see with image processing tool how many unique colors that it has. The number of unique colors is exactly as the original.

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (Ronounours) — Tue, 21 May 2013 04:13:53 -0700

Ronounours posted a reply:

I've done the same for Scale3x too :

pastebin.com/99pJwtmf

Reply to New filter for 2x scaling

nobody@flickr.com (jayprich) — Tue, 21 May 2013 03:41:48 -0700

jayprich posted a reply:

thanks Iain, interesting trick as halo/fringe or outright instability seems a big problem with all the sharpening methods
I gather 8bit per channel RGB bitmaps use a built in gamma-ish adjustment and the -srgb2rgb command corrects this to Linear RGB.
Then -rgb2srgb to convert back after interpolating.

In CImg.cpp this logic is done on a 0.0-1.0 float, but scaled back to 0-255
if( i<=0.04045 , i/12.92 , ( (i+0.055)/1.055 )^2.4 )

So your speed-up idea from "New Filter: fast formula" is relevant, replacing power with lookup.

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (garagecoder) — Tue, 21 May 2013 03:14:24 -0700

garagecoder posted a reply:

It does look interesting... I think the code just looks a little harder to understand due to optimisations but perhaps writing it from scratch wouldn't be so difficult. Would still take time though :)

Reply to PixelArt Scaling Algorithm

nobody@flickr.com (Ronounours) — Tue, 21 May 2013 02:55:16 -0700

Ronounours posted a reply:

HQX looks really interesting indeed. That would be nice if it could be done as a G'MIC command directly. Seems hard to code as a first glance though.
Just for fun, I've tried to code a version of Scale2x in G'MIC (already exists as a native command), and I was surprised to see that it was quite simple to do :

pastebin.com/atpepyYE

And its even shorter version :

pastebin.com/yvV5gMLU

Reply to New filter for 2x scaling

nobody@flickr.com (garagecoder) — Tue, 21 May 2013 01:50:56 -0700

garagecoder posted a reply:

Nice filter by the way, It does work well on low dimension images!