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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Split Compression

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Guy

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After reading this post:

http://www.reduser.net/forum/showpost.php?p=79549&postcount=38

I took a closer look at this image(48MB TIFF):

http://www.hdforindies.com/uploaded_images/B016_C001_070902_001_OCN.tif

After messing with levels and looking at the blue and green channels by themselves there is a noticeable change in the texture of noise in the sky between the top half and bottom half of the picture.

The change happens exactly(to the pixel) in the middle of the picture and is visible on both sides of the car.

To me it looks like that the top half of the image and the bottom half are being compressed independently of each other. It is probably much more apparent on images like this one where the top half and bottom half are very different.

I wonder if this is baked into the hardware of if it is something that could be changed with different firmware.

Graeme?
 
Probably the amount of data generated by the sensor exceed the bandwidth available from a single processor
in these case it could be handled by two separate chips one for the top half one for the bottom half.

In these case something isn't working properly giving different results.

it looks like the image has been processed with a soft median filter

Maybe an adaptive noise reduction filter is applied when capturing
so if like in these shot:
the top part is mainly sky
while in the bottom half has more elements with different colors and noise patters.
In these case an adaptive filter would have read two different scenarios applinig different corrections!

This joust an idea i've no knowledge about how Redone really works.
 
Best guess

Best guess

Here's my guess: The top half of the frame is mostly blue with very little detail. The blue channel got most of the bandwidth there, hence more detail in the blue channel as seen as grain. The bottom half has very little blue and lots of detail, so the red and green channel got nearly all the compression bandwidth. Blue didn't need much info for the bottom. Good info to know if you plan to do green or blue screen VFX work. Up until last week, I think most of us had never worked with 4K moving picture files (even though I'm just playing with files you guys have posted). RED truely is 4K for the masses!

Here's the images we're talking about:
RED_Compression_tile.jpg


697_1189372756.png


That came from the uncompressed file of this:
B016_C001_070902_001_OCN-797507.jpg


It would be best to also read this whole thead as well:
http://www.reduser.net/forum/showthread.php?t=4330&page=5
 
I have noticed the same thing way back when the first frames from "Crossing the line" were posted. I didn't want to mention it back then because it was from a beta camera.

I don't think the reason is that one particular channel is taking all the bandwidth. You can see the same effect in the following frame even if you don't watch a particular color channel. Observe well...
534_1189387100.jpg


For a full frame: http://www.red.com/skin/img/gallery-still/009000.jpg

the split is exactly on the middle of the frame!
 
De-Ja-Vu from JVC Split screen issue?
 
No, I am not suggesting anything. It is just a surprise issue that we went through JVC HD camera... The technical explanation must be given by RED, and I am not associated with them at all (just RED resrvation # 711).
 
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You can also see it here in the blue channel of the Garage TIFF(this is without any kind of manipulation), 100% crop:
 
I guess for those that really are going to use this as a replacement for their DSLR will have to use the raw port. I'm curious to see if this issue is something that will go away with improved firmwares? It seems like if they are use two separate processors to process the data, they could "talk" to each other and make the line go away. Maybe there was a hidden message in Crossing the Line (sorry I couldn't resist, I'm personally thrilled by the images I've seen so far).
 
SkyTower

SkyTower

After looking very hard, the split can be seen here slightly in the Skytower shot (this is 100% zoom and the contrast and brightness really cranked.) Interesting because the the city shot is from the same camera under similar lighting conditions.

697_1189394650.png


This is nothing when compared to the original JVC split processing problems. I'm not worried. In fact, I'm pretty happy with the image I get on my Canon XH-A1 most of the time. RED's image is far superior to it.
 
Can't trust the TIFF's

Can't trust the TIFF's

Ok, Look at this blue channel picture from Evin's post today of the updated PSgarage. This looks nothing like the what the old TIFF did here. It may be a slightly different frame, but it still has none on the split problems. I'm beginning to believe that you can't really trust uncompressed TIFFs or DPXs at all. What matters is only what you do in REDalert/cine with the raw files first.

697_1189397757.png


Guy, I assume that you were working on the TIFF from last week. Not PSGarage. I can tweak the old file to look like that as well.
 
In the latest fxphd podcast which covers RED they warn against judging posted images because it's like judging post telecine. It's not a true raw evaluation. They own camera 22. I don't know if that impacts this issue but keep it in mind.
 
JPEG's make a comeback.

JPEG's make a comeback.

Thanks Joelnet for the update. Good news everybody! Forget about downloading the massive TIFFs and DPXs. Wait and download REDCODE RAW files later when we have a copy of REDcine. For now, the JPEGs will do just fine. The TIFFs are just causing confusion.

It would still be nice to keep posting some of your best shots as uncompressed 4k as well.
4K PNGs would be great. See my other thread on PNGs.
http://www.reduser.net/forum/showthread.php?t=4487
 
RedRyan said:
Thanks Joelnet for the update. Good news everybody! Forget about downloading the massive TIFFs and DPXs. Wait and download REDCODE RAW files later when we have a copy of REDcine. For now, the JPEGs will do just fine. The TIFFs are just causing confusion.

It would still be nice to keep posting some of your best shots as uncompressed 4k as well.
Click to expand...

Is there a full moon tonight?
 
RedRyan i checked almost everything i have of stills and footage from the camera and i noticed that the split compression issue is mostly apparent with the JPEG captures and not in all of them.

Maybe the problem is not with the footage but with the way REDAlert exports the 4K jpegs.

I hope someone from RED will drop a line to illuminate the subject.
 
RedRyan said:
Guy, I assume that you were working on the TIFF from last week. Not PSGarage. I can tweak the old file to look like that as well.
Click to expand...

Yeah you are right, weird. Wonder why they are different?
 
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