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Hi,

I wrote a small raw decoding software comparison after I found out about Paul Lee's implementation of the new demosaicing algorithm for dcraw.

I haven't used the original dcraw much because of its horrible color artifacts. It seems the new algorithm clearly beats the old dcraw and the newest Bibble in image quality.

I wrote the comparison on a dedicated page because it uses a more or less user friendly Javascript hack to switch between the different images. Unfortunately it doesn't work yet with IE or Opera (works with Mozilla (Firefox)) but there's a link to the image directory so they can be downloaded nevertheless.

See the comparison at http://www.tkk.fi/~stanhua/rawcomp/

Oh, and the test image is of course taken with a D70, 50mm/1.8 @ 5.6.

S

Hi smt,

smt wrote:
I wrote a small raw decoding software comparison after I found out about Paul Lee's implementation of the new demosaicing algorithm for dcraw.

Thanks for pointing this out, I hadn't heard of it.

I haven't used the original dcraw much because of its horrible color artifacts. It seems the new algorithm clearly beats the old dcraw and the newest Bibble in image quality.

I hadn't found too much colour artifacts, but it could be just my untrained eyes. I looked at using Bibble, but since I have the D70s, Bibble does not support it yet

I wrote the comparison on a dedicated page because it uses a more or less user friendly Javascript hack to switch between the different images. Unfortunately it doesn't work yet with IE or Opera (works with Mozilla (Firefox)) but there's a link to the image directory so they can be downloaded nevertheless.

Very good comparaison. Certainly a big difference between Bibble and dcraw. The differences are minimal between dcraw and dcraw_ahd, but still there. As you said the colour artifacts do get removed in the AHD version.

I'll be giving it a try over the next few weeks. Do you know if Paul Lee's changes are eventually going to be merged back into the original dcraw?

cheers,

Radar,
aka André PS: like the way your "model" gets in the canoe.

Hi radar,

radar wrote:I hadn't found too much colour artifacts, but it could be just my untrained eyes. I looked at using Bibble, but since I have the D70s, Bibble does not support it yet

Well, granted, the artifacts are quite minuscule. But especially in architectural photography they distract me and once I'm aware of them, my eyes tends to pick them up even when the image is scaled down (to 1024x for example). Sharpening makes them even more visible.

I must admit I'm usually too critical of the image quality because small problems like dcraw's artifacts aren't usually too distracting in the prints. However, being a programmer myself, I hate problems introduced by bad software (in this case the VNG algorithm) when they can be fixed by simply writing better software. I was actually already started to experiment with different demosaicing algorithms in order to write a better one for dcraw, but luckily there's no need for it anymore.

Very good comparaison. Certainly a big difference between Bibble and dcraw. The differences are minimal between dcraw and dcraw_ahd, but still there. As you said the colour artifacts do get removed in the AHD version.

Thanks! I should pick also some more severe samples to show the differences between dcraw and dcraw_ahd but let's see if I have the time and inspiration...

I'll be giving it a try over the next few weeks. Do you know if Paul Lee's changes are eventually going to be merged back into the original dcraw?

I'm not sure. The same thing was speculated in dpreview's forums (where I found out about the AHD version) and I'd be very surprised if it doesn't get merged. The AHD is provided also as a standalone library and can be very easily patched to the newest dcraw in case it doesn't get merged. PS. Now the page works in IE too.

smt

-->smt

Just did a test, simple curiosity. Used your original.nef. NC set to:shappening = none. Export as 16-bit tiff. Then Photoshop unsharp mask with radius 0.20-0.22, amount 400-500%. Looks that gives much better result. Obviously is not freebie

Dcraw_ahd is not very far away, however difference is noticable. Bible way down.

Regards,

K.Polak

krpolak wrote:Just did a test, simple curiosity. Used your original.nef. NC set to:shappening = none. Export as 16-bit tiff. Then Photoshop unsharp mask with radius 0.20-0.22, amount 400-500%. Looks that gives much better result. Obviously is not freebie

But keep in mind that the samples in the comparison page aren't sharpened at all with USM (or any other external sharpening method)! Take the original.jpg (from img/, it's processed using dcraw_ahd) and apply the same 0.20-0.22/400-500% USM to it and then compare. I'd like to hear how it stacks up to NC after that...

My first intention was to include NC in the comparison, but it seems my vmware doesn't work anymore after kernel update for Linux. Bummer.

smt

-->smt

Good point. I will be happy to do that kind of comparision. Could I have dcraw_ahd-1.jpg in tiff format? Jpegs artifacts kill every comparition.

Regards,

K.Polak

There's now a tiff version of it available here:

http://www.tkk.fi/~stanhua/rawcomp/img/dcraw_ahd-1.tif (586k)

smt

-->smt

I have found this interesting. In fact it is not really matter of shapness as a edge lines. This I can match up increasing local contrast. However dcraw_ahd does very interestig thing: its definionion in 'larger' detail is better. It better defines tones ie middle strow has ballish, rounder look with finer sections definition with dcraw_ahd, wheras in nc its rather flat. And inreasing unsharp mask will not help, only follow to overshrpening hallos.

Regards,

K.Polak

krpolak,

I got NC up and running too and there're indeed some very small differences. If I'd have to decide which one is better I'd choose dcraw_ahd too, but the difference is minimal (yet visible when pixel peeping) so in practice they're equally good for all purposes. Also, they're equally slow. dcraw_ahd seems to be quite closely twice as slow as the original dcraw while Bibble is by far the fastest.

smt

I would be interested to know how RAWShooterEssentials2005 stacks up as well- being the best free choice for Windows users, from what I have seen.

My installation of RAWShooter seems to be playing up and blowing out highlights... i suspect I've changed something in it inadvertently tho. Might just re-install it and see how that goes.