Wednesday, August 4, 2010

Topaz Denoise 5 Review – Bad news … it mucks with colors! ** Updated–not as bas as I had thought …

I took a rather noisy 25,600 ISO image shot in the Blue Whale display at the Museum of Natural History in Manhattan (yes, the one in the movie) and processed it in ACR 6 with no sharpening or noise reduction. Then, I passed it through Topaz Denoise version 4 and 5 with the same default setting – RAW Strongest.

Both version produce a very clean output. But version 5 has a new feature that adjusts the black point, and by default it adds a magenta cast to the shadows. This is a bit funky looking to me. We’ll see that in a moment.

But first, kudos to the Topaz team for speeding things up rather dramatically. Version 4 processed the image in 48.9 seconds, which version 5 processed it in just over half that time – 27.7 seconds! Very well done. I remember timing Topaz Denoise when it first came out at about 6 minutes per file. And it was still worth it! But we’ve come a long way baby …

So let’s see the original image at 800px (remember to click on the thumbnail you see here to see the 800px version) …

DSC_2603_orig_ACR6[1]

Noisy, but not all that bad for the screamingly high ISO. Note that the room is actually quite dark. My exposure is a bit higher and the shadows have been opened somewhat, which exposes a lot of noise in the shadows. Still … tolerable.

When I unleash Topaz Denoise 4 on it, the colors and tones remain identical and the noise magically vanishes. Now, I would not leave the noise reduction quite this strong, but for the purposes of the demo I had to leave it exactly as Topaz processed it.

DSC_2603_TD4[1]

Well … that’s incredibly clean for 25,600 ISO. And there is still detail in the faces (a bit, not a lot.) This is a remarkable rendering of what I saw in a dark room. I’m very pleased.

A note on color balance … I set neutrals in ACR 6 on the left most post on the first floor. That gave a pleasing rendering for most of the elements in the room so I went with it. The incandescent lighting tends to win in this color scheme, with a very slight red tinge to everything.

Finally, Topaz Denoise unleashes a rather blunt instrument on the file.

DSC_2603_TD5[1]

Wow … that’s one seriously magenta floor … in fact, the shadows are all polluted with this cast. I have no idea what happened, but it perhaps is related to the new “correct black point” slider, which must be in the wrong position be default. Still, that would not account for the massive color shift. ** Update – it does. Black point is very sensitive to reds.

Here are three sets of crops to illustrate the problem …again, remember to click on each image to see the crops at 100%.

First, the three guys standing at the very bottom, left of center near the sign.

DSC_2603_crops_1[1]   

The color shift is very obvious here. When you look at the full sized crops, you also notice a slight loss of shadow detail. This causes things like the camera to flatten a bit. Not a big problem with elements that will appear very small in a print or web image, but in larger areas this could be an issue. There is somewhat more detail in the carpet though, so the tonal shift might work once they iron out the magenta problem. ** Update: I always watch the shadows and drop the black point until the colors do not shift.

Next, the area around the second floor railing on the left.

DSC_2603_crops_2[1]

Again, too much magenta. The area under the floor has some detail in the middle crop that is very dark and absolutely polluted in the bottom crop. The people on the left have lost a lot of clothing detail in the bottom crop as well. Here, the stronger contrast does not help as it did with the carpet.

Finally, the whale. By the way, all of the animals on display in this museum are real. Many were hunted in the 20s and 30s specifically to stock this collection. And since that can no longer be done, this collection has a pretty high value. It is simply stunning to see.

DSC_2603_crops_3[1]

And again, the magenta cast kind of wrecks the image. I’m not saying that the colors I got by setting white balance on that post were perfect. What I am saying is that a noise reduction algorithm has no business changing the colors at all, much less this dramatically.

** Update 26 Nov 2010 – I’ve been using Denoise 5 for a long time now and can say that this cast is an unusual circumstance. I still see the odd image that shifts like this, and it is always related to reds … so you cannot let it just do its thing, you must check the shadows. Other than that, though, Topaz Denoise 5 is a pretty incredible piece of software …

2 comments:

Filip said...

Hi, is seems like an common bug, that will be hopefully fixed early. Btw could you provide us the full resolution original image for comparison? Thanks F>

Kim Letkeman said...

Filip, click on the crops to see full resolution. I never link to full resolution images.