Red compression and matrix tests

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Photoshop is nowhere near as good as the real keying tools, at least when I'm trying to use it!

> I really wish they'd post some 2K footage...

If Redcode is only 27.5 MB/sec you'd think a few seconds would be feasible, seeing how many 72 MB TIFF files we're downloading. OTOH I haven't heard that the finished codec would ever be made public, let alone the current unfinished version. In the "already existing" field, MP4 is fairly efficient but there would always be questions about what is a compression artifact and what's "real".
 
jbeale said:
> I really wish they'd post some 2K footage...

If Redcode is only 27.5 MB/sec you'd think a few seconds would be feasible, seeing how many 72 MB TIFF files we're downloading. OTOH I haven't heard that the finished codec would ever be made public, let alone the current unfinished version. In the "already existing" field, MP4 is fairly efficient but there would always be questions about what is a compression artifact and what's "real".
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How about a compressed jpeg image sequence? Or jpeg 2000? Just a few seconds of 2K would be great!
 
Haakon said:
Wow, you guys are getting way better keys than I am... or does Photoshop just suck at this task?
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If you just use a magic wand or color range selection, yeah it sucks. There are proper techniques to get better keys, such as using the channel mixer to create an alpha matte or using plug ins from Primatte, Ultimatte or others.
 
I'm now several thousand miles away from my workstation so I can't do any tests... but I still want to :). Would someone do a difference matte on the two images? I can't believe we've gone 7 pages and nobody has performed THE test for compression quality.

Boothba, I'm sure you at least know what I'm talking about.

Thanks.
 
Boothba, I'm sure you at least know what I'm talking about.

Thanks.[/QUOTE]

Ya - busy night. All our systems are getting upgraded in the morning so I'm in archive hell. I'll try to fit it in.:)

edit - from what I've seen on this thread (and all things considered...) Redcode looks fantastic. Christ, the years I've spent keying blocky HDcam compression..........
 
im.thatoneguy said:
I'm now several thousand miles away from my workstation so I can't do any tests... but I still want to :). Would someone do a difference matte on the two images? I can't believe we've gone 7 pages and nobody has performed THE test for compression quality.

Boothba, I'm sure you at least know what I'm talking about.

Thanks.
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Here's a difference matte showing the compression. I think I did it correctly anyway... I pushed the levels to the extreme to get what you see here, so I suppose the difference really isn't all that much.

Sorry for the small size. Noise isn't easy to compress, but I guess that's the point right?

[edit] Does anyone have any idea what those large blocks are? [/edit]
 

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Red Channel Crop

Red Channel Crop

After looking at the compressed image more closely, it looks like REDCODE is removing mostly noise. There are a few spots however, where fine detail like hair is being removed.

Notice how in these two 100% crops of just the Red channel (the noisiest), some of the hair is disappearing with the noise. My guess is that Graeme has tweaked REDCODE even more to reduce this loss. I'm not disappointed at all, just pointing out how good the worst of the compression looks. :)
 

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Yes, I'm working on making it not eat into the details so much. It's working well so far. And yes, the "artifacts" of wavelet compression are, at light levels, mostly noticed as mild noise reduction. Indeed, wavelet transforms are often used in some noise reduction algorithms.

Graeme
 
Redcode dif tests

Redcode dif tests

Well I've had a chance to do some difference key tests between uncompressed and REDCODE-RAW and again I am extremely impressed.

As a frame of reference I was hoping to compare the results to HDCAM SR compression but unfortunately I could only get my hands on a dBeta deck. Both formats (HDCAM SR & dBeta) purport to be visually lossless at about 2:1 compression (opinions vary).

For this test I used three images sizes within a 720 X 486 10bit frame. The first image is a 100% crop of the 4.9K image, the second image is a 50% scaled crop (displaying 2K resolution) and the third image is about a 18% scaled crop (RED @ SD). I then difference keyed the uncompressed with the REDCODE image and compared that with a dif of the same image output to dBeta and re-input.

The first thing I noticed is that our dBeta deck needs a cleaning! :) The next thing to note is that REDCODE becomes more invisible when you scale down, to the point where it is (pixel for pixel) significantly better than dBeta (@ 2:1). This is great news for the tiny minority of us who will NOT be screening our films on a 4K projector - at least not for a while. But 4K aside, REDCODE should be able to deliver the finest 2K & HD commercially available to us plebs who can't afford a RAID. I will attempt to repeat this test when I get my hands on a HDCAM SR deck for a more official comparison.

Two things to remember:

ONE - I used the same difference key setting for all images, but the parameters are seriously cranked - the human eye would never see these anomalies.
TWO - dBeta is an widely accepted industry standard format. In North America the vast majority of SD shows are mastered onto dBeta (no BetaSP jokes). In fact a great many post shops still use dBeta as an archive format and broadcast content is often dubbed numerous times before hitting the air. Good to remember when you look at the bottom right image.
___________
Alex Boothby
 

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Graeme_Nattress said:
Yes, I'm working on making it not eat into the details so much. It's working well so far. And yes, the "artifacts" of wavelet compression are, at light levels, mostly noticed as mild noise reduction. Indeed, wavelet transforms are often used in some noise reduction algorithms.

Graeme
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Hmm... noise reduction and compression, all in one pass. Nice. :)
 
With DigiBeta, what you're mostly seeing are the problems ofRGB to Y'CbCr 4:2:2, which does some quite nasty things to edges. And what you're not seeing is the 12bit to 10bit, but that's trickier to see, but once you get the data into REDCINE, it makes the world of difference.

Graeme
 
I think the images from the Mysterium sensor look very good. One thing I’ve noticed though is that the debayer algorithm is doing somewhat odd things with hair.

hair100cropxu5.png
 
jack78 said:
I think the images from the Mysterium sensor look very good. One thing I’ve noticed though is that the debayer algorithm is doing somewhat odd things with hair.
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Really? It just looks a little soft to me, probably due to the lens not being perfectly perpendicular to the sensor. What odd things are you referring to?
 
Difference maps show the CODEC compromises mostly noise and very small detail. Looks flattering on talent too. REDCODE images are going to scale and compress very nicely for HD delivery. If digitally projected, I think that I'd be inclined to add digital grain, not a bad problem to have... Congrats, very impressive so far.
 
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