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Tom Lowe
12-18-2008, 07:58 AM
Hopefully I am not suggesting something that is already announced or in the works... :blush:

With native, full-sensor resolution in the neighborhood of 6K, it sure would be nice to have a half-scale sRAW option. I notice that on my 5D2 when I shoot full-sensor, 21MP RAW files and import them as footage into AE, my CPU gets destroyed. Like, I set the thing to render, then I can take a 2-day trip to Catalina while I'm waiting for it to finish. :ohmy:

But I did shoot quite a few scenes in sRAW, which is only roughly 1/2 res but maintains all the flexibility and power of RAW.

RAW = 5616 x 3744 (21.0 MP)
sRAW = 3861 x 2574 (10.0 MP)

The images created by sRAW are super clean, sharp and beautiful. Perfect for 2K finishes. This saves CF cards, and spares my CPU the humiliation of 5.5K!!

I notice on Epic FF35's specs it says:

6K 1-100fps
5K 1-125fps
4K 1-150fps

FF1080p 1-60fps

I assume the 5K and 4K are cropped? Is that FF1080p basically a scaled down RAW, or some type of processed RGB or something?

I don't have a clear understanding of how Canon's sRAW process works, but I can tell you one thing: it works beautifully.

Shot sRAW1....

http://i42.tinypic.com/28jw1w4.jpg

Graeme Nattress
12-18-2008, 08:06 AM
The "half high" direct demosaic of 4k to 2k probably gives you the benefits you'd need - speed and quality, but it doesn't stop you going back to the 4k RAW if needed.

Graeme

Tom Lowe
12-18-2008, 08:10 AM
Graeme, do you understand how Canon is doing their sRAW?

I'm curious to know how it works.

Graeme Nattress
12-18-2008, 08:11 AM
I know of a number of possible ways that they could be doing it. The major advantage for Canon is that you get a smaller RAW file to write in camera. That's not so much an issue with the speed we can write files.

Graeme

Tom Lowe
12-18-2008, 08:17 AM
I tell you, though, it is nice to be able to select that sRAW in the field.

Graeme Nattress
12-18-2008, 08:35 AM
The sraw is probably doing some kind of binning. That could lead to excessive aliasing. I'll have to investigate further...

Tom Lowe
12-18-2008, 08:55 AM
Just tell Jim you need a 5D2 right away for your investigations. :) :wink:

Graeme Nattress
12-18-2008, 09:01 AM
I think my 1D mk III does sraw too...

Deanan
12-18-2008, 10:06 AM
IMHO, REDcode with a half res high decode is superior to sRAW in many ways. The downsampling that sRAW uses is not very elegant.

Daniel Browning
12-18-2008, 10:09 AM
You already know how I feel about this from past threads, Tom, so don't feel like you have to respond, but I want to post the following anyway so that everyone else knows how much I am annoyed by Canon's sRAW mis-feature.



With native, full-sensor resolution in the neighborhood of 6K, it sure would be nice to have a half-scale sRAW option.


I think it would be nice, too, as a very last resort, after all the better compression methods are implemented and you still need smaller file sizes.

Asking RED for something like this is like asking Mario Andretti if he can also drive 5 MPH go carts, or asking Michael Phelps if he can also swim in the kiddy pool. RED can do it, sure, but they left the kiddy pool long ago.

Below I'll discuss why Canon's 21 MP RAW should be 3 MB instead of 26 MB, even at full resolution.


...21MP RAW files and import them as footage into AE my CPU gets destroyed.

There are several solutions to this, including, as Graeme mentioned, things like RED's half-high demosiac or faster full-res algorithms. Even in the worst case scenario, software could always convert the full res RAW down to sRAW after the fact. Adobe is definitely not a good example of providing flexibility in choosing demosiac algorithm.

Things like sRAW should solve in-camera challenges (card space, etc.), not Post challenges that have better solutions.



I don't have a clear understanding of how Canon's sRAW process works,


I don't either. My current theory for 5D2 sRAW1 is that two GB/RG groups (8 RAW pixels) are converted to two pixels that have unique G, but the same R/B.



But I did shoot quite a few scenes in sRAW, which is only roughly 1/2 res but maintains all the flexibility and power of RAW...it works beautifully.


What is the purpose of sRAW? To reduce file size.

How does it achieve this? By throwing away resolution.

Is that the best Canon could think of? The very first time they try to reduce file sizes and nothing else comes to mind except to immediately start dumping pixels?

It's like a plane with 21 passengers and a cargo hold full of garbage. When the plane is too heavy, Canon immediately resorts to throwing passengers out of the plane, while keeping all the garbage.

I'm glad RED didn't suffer that kind of tunnel vision, REDCODE sRAW would be 168 MB/s (1344 Mbps) and only 3K.

That's why sRAW is the laughing stock of file formats. In some cameras, like the 50D, half of the sRAW2 filesize is wasted on two embedded jpegs, and the rest only contains a quarter of the resolution.

First of all, there's a simple nonlinear bit-depth compression they could do, like Nikon. The difference is invisible to the human eye, but that alone saves a tremendous amount of disk space.

Next, they could make the embedded jpegs optional, at the cost of making reviews a little slower. (I don't use the embedded jpegs anyway since Canon also doesn't bother providing truly raw RGB histograms and I have to use UniWB).

After that they could compress bit-depth on a scale of exposure. You don't need 14 bits to record a scene at ISO 12800. Six or maybe 7 bits would be enough to encode the entire signal down to the noise floor. For every stop that exposure is decreased, the noise floor gets higher. The bit depth should be decreased to match the noise level. This compression wouldn't help or affect base ISO shots at all, but would make a huge difference for high ISO shots.

On the subject of bitdepth itself, the noise in the camera at base ISO isn't even clean enough to require 14 bits. 12 bits is more than enough to encode the entire range of signals as well as a half-stop of noise. This has been tested (http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/) and the last two bits are truncated in post and it makes no difference.

Now that's four things that reduce filesize without *any* affect on the resulting image. Still has full resolution, RAW, etc. My calculations show that for a high ISO shot, file sizes would be 1/8th what they are now. That's 3 MB for the 5d2. I'd much rather have that then the half-resolution 15 MB files Canon has now.

But why stop there? There is an entire world of compression they could apply to the image with imperceptible affect on image quality. Cineform RAW and REDCODE show that technology exists to reduce file size in ways that are visually lossless to the eye. At the very least, the "lossy" effect will be much smaller than just dumping entire pixels. Unlike the methods I've already discussed, many of these methods, I'm sure, require some CPU power in the camera.

If the camera is too weak to do any sort of medium-to-advanced compression (and it probably is), then sRAW would be an acceptable compromise. But not until all the better ideas, the least of which are outlined above, which do not require any camera CPU power, are already implemented.

In the case of RED, it would be nice if they offered this type of lossy compression so that filesizes were reduced and recording time increased, but only after the camera CPU is taxed to the limit with the more efficient methods.

Graeme Nattress
12-18-2008, 11:21 AM
9390

Canon 1D MK III, 50mm F.14, locked off on tripod, shot both RAW and sRAW.

Daniel Browning
12-18-2008, 11:29 AM
Canon 1D MK III, 50mm F.14, locked off on tripod, shot both RAW and sRAW.

Ewwww! Another and even more important reason to hate sRAW: aliasing artifacts. Doesn't look like Canon even *tried* to filter out details from the new Nyquist before they resampled.

Maybe Canon should rename sRAW to 'Sigma Foveon mode': less resolution and more artifacts. (They still need to do worse in the low light performance before they'll match Sigma in that regard.)

Tom Lowe
12-18-2008, 07:16 PM
Graeme, in all fairness, test the 5D2's sRAW.


IMHO, REDcode with a half res high decode is superior to sRAW in many ways. The downsampling that sRAW uses is not very elegant.

I don't know what to say. It seems extremely elegant so far IMHO. These images I am seeing at 2K finish are beautiful. Plus the fact that you are only recording 1/2 the CF card space. That is useful.

A lot of pixel peepers at DPR and some astro guys are saying that sRAW on the 5D2 gives you the beauty of full frame plus the benefits of a downsample (in terms of noise reduction).

I'm just reporting what I have heard.

Chris Kenny
12-18-2008, 11:25 PM
Downscaling is never as effective in terms of preserving significant image data while reducing file size as is a modern image compression algorithm. As an extreme example of this, consider the fact that REDCODE 28 has about the same data rate as SD uncompressed video. Clearly we're much better off with REDCODE than we would be if the Red One downscaled everything to SD before recording it.

Downscaling does have the benefit of requiring much less processing power, which might matter in some embedded applications, but clearly isn't an issue with Red's gear; high-quality compressed raw recording is practically the centerpiece of Red's technology program.

conrad gaunt
12-19-2008, 03:26 AM
My understanding is, the new Red cameras will downsample FF to 1080p, and save it as a wavelet compressed RGB file, not a RAW file (like cineform RGB perhaps).

This will give you a measure of oversample, which brings a little noise reduction, anti-aliasing and what i call "density", that sRAW and CFAs don't (and it'll take less space than a Canon sRAW file).

This will be useful for when 4k is overkill on smaller productions, but downsampling a Full quality debayered 4k frame, then downsampling with a high quality software downsampler is my prefered route when time allows.

What would be amazing is if Reds RGB format could go beyond just being an "injest only" format.

Better still would be a lossless wavelet version of redcode, that could be exported to (like cineform RGB, but bigger, slower, lossless, so no toes trodden on!)

Tom Lowe
12-19-2008, 03:36 PM
Here is what the illustrious Ken Rockwell has to say about sRAW...


Try shooting your 5D Mark II at it's M (11MP) or S (5MP) settings. If you look at your images at 100%, you'll see that the lower resolution shots are sharper!

Why? Because they use less, or no, Bayer interpolation. No digital camera really resolves its rated resolution; they cheat and interpolate up, so at 100% at its rated resolution, no digital camera image is as sharp as a true scan from film.

At the 5MP setting, you have 100% R, G and B pixels, exactly as if you were using a Sigma Foveon sensor. If Sigma was selling this, they'd sell the 5MP (S) setting as if it were 15MP (also a lie).

http://www.kenrockwell.com/canon/5d-mk-ii.htm

Graeme Nattress
12-19-2008, 04:25 PM
I don't think it wise to ever base a photographic / imaging argument around anything Rockwell has to say. The images I took speak for themselves in what is happening.

Graeme

Jannard
12-19-2008, 05:22 PM
Looks like Canon IS having some sRAW issues with the 5D II...

http://www.dpreview.com/news/0812/08121902canon5ddots.asp

Jim

Tom Lowe
12-19-2008, 05:29 PM
I don't think it wise to ever base a photographic / imaging argument around anything Rockwell has to say. The images I took speak for themselves in what is happening.

Graeme

Lol I'm not vouching for Rockwell, I just posted what he had to say.

So Graeme what do you think they are doing exactly to accomplish this sRAW?

I Bloom
12-20-2008, 12:03 PM
Now I'm trying to figure out what the Red FF1080p mode is.
I'm hoping it's fully debayered, scaled to 1080p RGB, wavelet compressed. But thinking that's impossible or maybe not necessary.

IBloom

Graeme Nattress
12-20-2008, 12:38 PM
Whatever FF1080p is, it will be done "properly". No need to worry about that!

Graeme

Tom Lowe
12-22-2008, 03:41 PM
One more thing I noticed, Jim and Graeme, is that when I'm shooting sRAW, my Canon 5D2 can shoot much, much higher FPS... almost twice as fast as with RAW. Could an sRAW-like option allow for higher framerates with Epic and Scarlet?

I realize that the downsampling might not be 100% perfect, but still, if it could significantly increased FPS while maintaining RAW capabilities, couldn't that potentially be useful?

Graeme Nattress
12-22-2008, 05:36 PM
In the Canon, it's not the sensor that's running at double speed, but that the write speeds to the CF card are twice as fast due to half as much data. REDCODE RAW is much more efficient in this regard. So, yes, it will increase the fps for the Canon, but not for the REDs which already run at a much higher fps.

Graeme

Deanan
12-22-2008, 06:17 PM
One more thing I noticed, Jim and Graeme, is that when I'm shooting sRAW, my Canon 5D2 can shoot much, much higher FPS... almost twice as fast as with RAW. Could an sRAW-like option allow for higher framerates with Epic and Scarlet?

I realize that the downsampling might not be 100% perfect, but still, if it could significantly increased FPS while maintaining RAW capabilities, couldn't that potentially be useful?


Part of that is because of the throughput to the cards.
However, REDcode raw will be significantly faster than anything else in Scarlet/Epic.

Edit: what Graeme said :)

Tom Lowe
12-22-2008, 06:50 PM
Hmmm.. I don't know if I'm understanding 100%.

Yes, with the Canon, the FPS gain comes mainly from the limitations of the throughput to the CF cards, for sure. I know this because I tested various cards - x133, x233, x300, etc - shooting RAW, sRAW1 (1/2 res) and sRAW2 (1/4 res).

But if you cut the amount of REDCODE RAW data on the 6K FF35 Scarlet or Epic (to FF 35mm REDCODE sRAW 3K), for example, couldn't the same processors and CF cards (or SSDs or whatever) capture and record roughly twice the number of frames? Or is it the sensors themselves that have the speed limitations?

Graeme Nattress
12-22-2008, 07:22 PM
There are two kinds of compression going on here, a RAW visually lossless REDCODE, and a uncompressed decimated RGB RAW (basically what sRGB is doing). One works on a perceptual transform basis (the wavelet bit), followed by an entropy encoder (packs what's left tightly together), the other work by binning (basic averaging) then decimating (throwing bits away), with perhaps some simple entropy encoding to pack things together.

Say for instance doing the sRAW binning / decimation to get the resolution down was done, followed by the REDCODE wavelet stuff - you're now putting less resolution through the REDCODE, so you can make it's life easier. Yes? Probably not... Because inadequate filtering has occurred, you're trying to fit more resolution than the pixels dimensions can handle. In real life when you put more than a pint of beer in a pint pot, the beer spills out and makes a mess. In image processing, the beer folds back on itself and corrupts the image - aliasing, but just another mess of beer really. Aliases are spurious false data that are not correlated with the actual detail in the image. They make an image harder to compress, as they're effectively noise, or extra detail that's not actually part of the image.

In the end, even if you matched data rates on a per pixel basis, you're effectively comparing 4k RAW at say 36MB/s with 2k RGB at 27MB/s, and the 4K RAW properly demosaiced and downsampled to 2k RGB is going to look better, especially if there's any high detail or repetitive high detail in the scene. On motion, it will look a lot better as aliases look worse in motion as they move in the opposite direction to the motion. The image will survive through the broadcast chain more effectively as aliases are spurious false detail that the broadcast compression has to encode as it doesn't know, and can't know it's not real image detail. Like noise, aliases harm compression schemes. Also, in motion, they screw up motion estimation as they move in the opposite direction.

One of the perceptual issues with motion imagery is that the perception of judder is increased on sharp edges. Inadequate filtering on downsample increases edge sharpness considerably, and hence contributes to the perception of motion judder.

But to answer your question, RED's sensors do have speed limitations. Nothing like the speed limitations on the Canon sensors though... Normally on a CMOS, each line you read out takes time. The more lines you read, the slower it takes to read out a whole frame. That is why we can go faster in 3k than 4k, and a lot faster fps in 2k. All makes sense. If the 5D2 is only reading 1 line in 3 say, then it's not a 30fps sensor, but really a 10fps sensor. I think that really puts what RED is able to do, speed-wise on it's sensors into perspective. Given the mirror shutter is hard to run much faster than 10fps, why would stills photo sensor designers even want to try to make the sensors run faster than that? for more speed would cause all manner of engineering difficulty and cost.

Graeme

Tom Lowe
12-22-2008, 08:01 PM
There are two kinds of compression going on here, a RAW visually lossless REDCODE, and a uncompressed decimated RGB RAW (basically what sRGB is doing). One works on a perceptual transform basis (the wavelet bit), followed by an entropy encoder (packs what's left tightly together), the other work by binning (basic averaging) then decimating (throwing bits away), with perhaps some simple entropy encoding to pack things together.

Say for instance doing the sRAW binning / decimation to get the resolution down was done, followed by the REDCODE wavelet stuff - you're now putting less resolution through the REDCODE, so you can make it's life easier. Yes? Probably not... Because inadequate filtering has occurred, you're trying to fit more resolution than the pixels dimensions can handle. In real life when you put more than a pint of beer in a pint pot, the beer spills out and makes a mess. In image processing, the beer folds back on itself and corrupts the image - aliasing, but just another mess of beer really. Aliases are spurious false data that are not correlated with the actual detail in the image. They make an image harder to compress, as they're effectively noise, or extra detail that's not actually part of the image.

In the end, even if you matched data rates on a per pixel basis, you're effectively comparing 4k RAW at say 36MB/s with 2k RGB at 27MB/s, and the 4K RAW properly demosaiced and downsampled to 2k RGB is going to look better, especially if there's any high detail or repetitive high detail in the scene. On motion, it will look a lot better as aliases look worse in motion as they move in the opposite direction to the motion. The image will survive through the broadcast chain more effectively as aliases are spurious false detail that the broadcast compression has to encode as it doesn't know, and can't know it's not real image detail. Like noise, aliases harm compression schemes. Also, in motion, they screw up motion estimation as they move in the opposite direction.

One of the perceptual issues with motion imagery is that the perception of judder is increased on sharp edges. Inadequate filtering on downsample increases edge sharpness considerably, and hence contributes to the perception of motion judder.

But to answer your question, RED's sensors do have speed limitations. Nothing like the speed limitations on the Canon sensors though... Normally on a CMOS, each line you read out takes time. The more lines you read, the slower it takes to read out a whole frame. That is why we can go faster in 3k than 4k, and a lot faster fps in 2k. All makes sense. If the 5D2 is only reading 1 line in 3 say, then it's not a 30fps sensor, but really a 10fps sensor. I think that really puts what RED is able to do, speed-wise on it's sensors into perspective. Given the mirror shutter is hard to run much faster than 10fps, why would stills photo sensor designers even want to try to make the sensors run faster than that? for more speed would cause all manner of engineering difficulty and cost.

Graeme

Graeme, most of that went straight over my head, as usual. :) I think I will reread it a couple times.

A couple quick things, though. I was talking about fast-FPS stills shooting in RAW vs sRAW1 vs sRAW2. Not video. Although you and Jim and Deanan are kind of dissing the sRAW process, I'm not really seeing it on my end, rendering out gorgeous and (to my eyes) alias-free 2K high-definition video.

You said, "you're effectively comparing 4k RAW at say 36MB/s with 2k RGB at 27MB/s." But I'm not sure I follow. With Canon's 5D2, a full RAW image is 20MB, but the sRAW1 (1/2 res) still is only like 9MB. So the amount of data has been roughly halved.

Are you saying that the REDCODE processing would struggle with the sRAW half-res because it's jagged and has aliasing?

Also, are the limits on FPS, like 6K@100FPS for FF35 Epic limits of the sensors, mainly, or limits of the processing? I remember with R1 Jim said processing was the actual bottleneck.

But what about FF35 Scarlet? Does it use the same exact sensor as FF35 Epic, only with less horse-power for processing? Or is the sensor's read-reset speed actually slower? If they are the same sensor, couldn't you guys offer a 1/2 res onboard sRAW (or whatever term you prefer! :)) that would allow Scarlet FF35 to roughly double its FPS, at 3K REDCODE sRAW, for example? Please. :):innocent:

Jarred Land
12-23-2008, 12:23 AM
Good discussion...

Do you really use sRAW on your Canon Tom?

Thats one of those things i really never understood.. Its been around for awhile now, i've turned it on once but just don't understand the logic behind it.. it's a bit of an oxymoron to me.

Tom Lowe
12-23-2008, 12:36 AM
It's funny because I didn't think I would use the sRAW, but a couple weeks ago I was shooting some high-speed timelapse (drivelapse) and was basically left with no choice. The fastest CF cards I had were Lexar 8GB x300s, and they would bog down after about 50 frames when I was shooting 1/3s continous RAW.

So I had to switch to 1/3s at sRAW 1/2 res, and then the CF cards could keep up. With sRAW2 (1/4 res) I was able to shoot at 1/4s continuous.

Later that week I started using sRAW just to save card space for some long timelapses and when I processed the clips, I have to say, they looked fantastic at 1080p or 2K.

Not to mention that all my full-on RAW 5.5K 5D2 image sequences nearly brought my desktop to its knees when I was working on and rendering out the clips in AE. :ohmy:

So now I am going to use full 21MP RAW for the top-of-line shoots, and sRAW for just average shoots that only require a clean 2K finish.

Jarred Land
12-23-2008, 12:42 AM
mmmm looks like you found a use for them. Are you using the DNG converter to convert your sRAW files? nothing opened even normal RAW properly when i got my 5D2 a few weeks back.. it sounds like you have had better luck, even working with sRAW in AE?

Tom Lowe
12-23-2008, 01:06 AM
You need CS4 and the new Adobe Camera Raw plugin for CS4. It works great, though. In AE, for rending timelapse clips, I work with the RAW files or sRAW files directly (AE can ingest them, just like Photoshop). The RAW image sequences are right in the timeline. Then I make 1080p or 2K or 4K masters right off the RAWs. The quality is superb.

Come to think of it.. I'm probably one of the few random joe six pack type guys around here who is already doing 5K or 6K RAW video editing and processing right now. :) And I can tell you.. my editing computer is not happy! Luckily we have another year or so before FF35 really hits the streets. Plenty of CPU power is going to be needed for those cameras.

Jarred Land
12-23-2008, 01:12 AM
yeah just checked.. the ACR plugin from last week covers the 5D2.. good to see.

Your right about CPU power.. I am hoping Apple releases some heavy machinery next month, its kinda been awhile...

Deanan
12-23-2008, 01:22 AM
A couple quick things, though. I was talking about fast-FPS stills shooting in RAW vs sRAW1 vs sRAW2. Not video. Although you and Jim and Deanan are kind of dissing the sRAW process, I'm not really seeing it on my end, rendering out gorgeous and (to my eyes) alias-free 2K high-definition video.


We actually tested decimated raw against redcode a long time back even before we optimized REDcode and there was no comparision.

Aliasing is something that varies alot with subject matter. We tend to do alot of stress testing because while one scene may look ok, another can look horrendously aliased.

Tom Lowe
12-23-2008, 07:33 AM
We actually tested decimated raw against redcode a long time back even before we optimized REDcode and there was no comparision.


In terms of "decimated RAW" (sRAW) vs REDCODE, does it have to be one or the other? REDCODE, right now, does not offer an in-camera 1/2-res RAW option, does it?

Graeme Nattress
12-23-2008, 07:36 AM
My long comment above was that decimating to a lower resolution raw, then putting it through REDCODE would not result in a better image than REDCODE as is, and post scaling properly. The file size advantage wouldn't actually be as great because the aliasing would thwart the compression.

Graeme

Tom Lowe
12-23-2008, 07:38 AM
My long comment above was that decimating to a lower resolution raw, then putting it through REDCODE would not result in a better image than REDCODE as is, and post scaling properly. The file size advantage wouldn't actually be as great because the aliasing would thwart the compression.

Graeme

But what about saving data space and processing power (and any benefits that might enable) in camera, in the field? You're certain that REDCODE would struggle with the 3K 1/2-res RAW? If that's the case, then yeah, maybe it's not worth pursuing or thinking about.

Stuart English
12-23-2008, 07:47 AM
when I'm shooting sRAW, my Canon 5D2 can shoot much, much higher FPS... almost twice as fast as with RAW.

Could an sRAW-like option allow for higher framerates with Epic and Scarlet?

Rather than dig any deeper into the design logic behind this Tom, the answer is no.

Graeme Nattress
12-23-2008, 07:55 AM
The sRAW approach is the simplest way to reduce RAW file size. It's as simple as it is "wrong" from an imaging point of view. REDCODE RAW is a vastly non-trivial solution to the "problem", but in the end, a more elegant and powerful solution.

Graeme

DSPographer
12-23-2008, 08:57 AM
The sRAW approach is the simplest way to reduce RAW file size. It's as simple as it is "wrong" from an imaging point of view. REDCODE RAW is a vastly non-trivial solution to the "problem", but in the end, a more elegant and powerful solution.

Graeme

Graeme,
Couldn't you just throw away the highest frequency information in the redcode frame before the entropy encoding? It seems to me that would achieve the resolution of sRaw without any aliasing. It might seem that a more flexible allocation of bits for each frequency would be better but sometimes the user may already know they don't want the full resolution of the sensor area they are using.
By the way, based on how soft some of the posted Canon sRaw files look I think that Canon may be doing a true anti-aliasing filter for sRaw instead of just binning pixels. [Edit: I was referring to some 5D2 sRaw1 images that have been posted that looked soft. After looking at the image Graeme posted it looks like his camera does have luminance aliasing in sRaw mode.]

Graeme Nattress
12-23-2008, 09:13 AM
Sure, that'd work, but at that point, why? You may as well keep the details. It doesn't solve any problems for us though.

Based upon the sRAW image I shot above, you tell me what you think they're doing! I think the exact nature of the sRAW is different in different Canon cameras, but I think it's obvious that what's going on in the sRAW I have access to.

Graeme

Jannard
12-23-2008, 11:05 AM
Before anyone says, "can't you guys do it like XXXXX?", I'd suggest putting XXXXX through the same scrutiny that RED is subject to BEFORE asking the question. Why would we want to do sRAW when it sucks so bad?

There is an assumption with the "big guys" that they must be doing it right... when that is not necessarily the case.

Just saying...

Jim

Tom Lowe
01-09-2009, 12:03 PM
Heh. You guys keep dissing sRAW, but I am not seeing it in the results I am shooting with the 5D2 in 1/2 res sRAW. In fact, the results are absolutely stellar (from what I can see). Granted, I only have a layman's eye for this type of thing.

One thing I wonder about is this: If you are shooting 5k or 6K, you are going to have to downsample to 4K or 2K or 1080p one way or another. Is After Effects' bicubic downsampling any better or worse than Canon's in-camera sRAW downsampling? Even if they are in the same ballpark, then the convenience of shooting only 1/2 RAW in terms of recording media and post production would be very substantial, and would get a lot of use from S35 and FF35 DSMC shooters, IMHO.

I guess another way to ask this is, once you run your full-res RAW through your demosaicing and downsampling, are you going to see similar artifacts with zone plate tests?

BTW, on a related note, is the full-sensor onboard 1080p recording option going retain some of the felxibility of RAW in terms of color temp, sharpening, etc?

Graeme Nattress
01-09-2009, 04:08 PM
Bicubic is pretty poor as a downsample filter goes. Box filtering is worst, and that's what sRAW is looking like to me. For the best downsampling, lanczos is pretty nice. We use something pretty special in our 4k to 2k downsample which doesn't have a fancy name, but it looks lovely.

If you do a full demosaic and downsample you will get better results.

Graeme

Tom Lowe
01-22-2009, 06:36 PM
By the way, I might be eating some crow here pretty soon. I have been shooting a lot of sRAW1 (1/2 RAW) timelapse sequences under varying conditions (light, texture) with the 5D2, and some possible flaws (banding, moiré) have been popping up in some of the rendered shots. What that means is that while 80% of the sRAW1 shots might look fantastic, it appears that certain conditions might trigger artifacts, banding, and moiré patterns. If this does turn out to be the case, then as Graeme and Jim have said, it would make this function nearly useless. No one wants an unpredictable camera.

I'll update this when I get a chance to really do some more testing of sRAW vs full RAW.

Graeme Nattress
01-22-2009, 06:42 PM
That's pretty much why we try to be careful about aliasing and moire - you never quite know when it will show up and cause bother. Thanks for your continued input Tom.

Graeme

Shane Betts
01-23-2009, 04:27 AM
Sorry to hijack the thread. I'll give it back in a minute...:innocent:

One thing that started Tom on this discussion was the way his CPU groaned under the weight of processing the larger RAW files, one solution he saw was files of half the size. Now, he's beginning to see the flaws in Canon's technique whilst their file sizes are still massively larger than Red's but there is another possible solution to his CPU woes that I can see.

If, as Graeme has suggested, the upcoming Epic has the potential to demosaic on the fly to downsample to 1080, couldn't it also be possible for Red to build the same processing power into a PCI card to speed up the process in post? That way Red could hold onto their proprietary R3D codec and make all our lives a nicer place to be.

Who better than Red to unravel R3D files? Anyone from Red care to comment?

Anders Zakrisson
01-23-2009, 07:10 AM
If, as Graeme has suggested, the upcoming Epic has the potential to demosaic on the fly to downsample to 1080, couldn't it also be possible for Red to build the same processing power into a PCI card to speed up the process in post? That way Red could hold onto their proprietary R3D codec and make all our lives a nicer place to be.


Much better to use a graphic card with some kind high-level programming (eg. Nvidia with CUDA) to do that instead of building a custom card. There's an incredible amount of processing power waiting to be harnessed for these kinds of activities available in the current generation of GPU's.

Shane Betts
01-23-2009, 11:51 PM
Much better to use a graphic card with some kind high-level programming (eg. Nvidia with CUDA) to do that instead of building a custom card. There's an incredible amount of processing power waiting to be harnessed for these kinds of activities available in the current generation of GPU's.

It's a daunting task to write GPU calls which is probably why we are still waiting for any genuine help from the currently available GPU's. Whereby, building a PCI card, given that they've already written the code and have already designed the hardware to do the job in camera, should be fairly simple in comparison. And, with the cost of PCI cards being so small, who cares if we bought them now and the GPU path catches up in a year or two? Way cheaper than buying a bunch of extra CPUs to help out.

Tom Lowe
03-30-2009, 12:59 PM
I just wanted to dig up this thread to say once and for all, after more testing, that sRAW is nonsense. I'm seeing all kinds of crazy artifacts in all the sRAW stuff I shot. :(

Jim, Jarred and Graeme were all spot-on correct on this.

Graeme Nattress
03-30-2009, 01:00 PM
Thanks for the feedback Tom. It's really appreciated.

Graeme