Serious scaling artifacts still present in CC

Question

Hello,
Of course I was tracing forums for the issue dating back to CS5.5.
I mean scaling artifacts. Picture attached.
To reproduce it, please create a solid, then apply a strong noise, and then upscale or downscale image for about 4 or 7%.
You will see a grid pattern on the noised layer. It also appears on the footage when any scaling operation is performed. Test by yourself.
I spotted this when my first movie was screening in 2k cinema. Then I started to look up for solution.
In AFX CC you introduced new bicubic scaling, but it is only enhancing image, downscale artifacts are still present.
It is not a viewport issue. It is present after rendering in high quality scaling.
My orginal footage is not recorded with this artifact, I am sure. I use noise to prove it. Noise at 100% scale is perfect. Changing it makes grid pattern visible.
From coding point of view, I presume there is a problem with dividing, or sampling infinite fractions. The artifact grid square is 16x16 pixels small.
Test your own footage.
Too bad warp stabilizer does it too.
I was hoping the problem is solved in CC, but its not. It really can be visible in films. Premiere, on the other hand, seems to be free of it.
Adobe Guys?
All the best.

Answer 1

Couple of things. If you scale or reposition footage so that the original pixels values are used to calculate new pixel values that do not precisely line up with the originals. If there is any pattern of noise or detail in the video there is a good chance that the pattern become visible. Noise is a pattern. Adding noise at 100% to a footage layer and then scaling as you demonstrated with your first screen shot will reveal this pattern. AE's Noise effect generates noise on a 16 X 16 pixel grid so if you scaling has the chance of emphasizing that pattern. This is not a bug but rather a mathematical certainty most obvious at odd numbered or fractional values. Different scaling algorithms use different formulas to attempt to hide these problems and maintain apparent detail. The only way to completely hide the pattern is to use a scale factor that evenly divides or multiplies the pixels. One pixel becomes 4 or 4 becomes 2 for example. When 4 pixels become 3 fractional the fractional values emphasize any pattern that exists in the original image.
Second point. If your original footage came from any kind of compressed source, like from a DSLR or anything other than a professional video camera that has the capability of shooting uncompressed or lossless footage, your footage will use a compression scheme that uses 16 X 16 or larger blocks of pixels in the compression system. Any footage that is shot with any chroma subsampling other than 4:4:4 will also develop a pattern in the chroma if scaled so the pattern is introduced. This tells me a couple of things about your second screenshot. I would guess that the original footage was fairly noisy and that it comes from an MPEG source like a DSLR or consumer camcorder. Adding an effect like Unsharp mask to the scaled layer will only emphasize the pattern. The less noise in the shot the less visible the pattern.
Last point. Noise and grain move and the patterns are less discernible with the footage is moving. Judging the final output quality can only be done when the footage is playing back at the actual playback speed on the actual delivery device. If you really want to know what a shot is going to look like you have to play it back on the device you are going to be using for final output. If you are going to a film festival and your footage is going to be projected you have to test it on a projector.
Ok, the very last point, just to emphasize the importance of positioning. Any time you reposition a source layer to a position that causes the pixels to be reinterpreted in any way the image will degrade and there is nothing you can do about that. Scale, position and rotation all dramatically effect the quality of the image and potentially introduce repeating patterns if the pixels do not line up exactly with the pixel grid in the composition. If your scaling introduces repeating patterns in your image then the only solution is to hide those patterns by adding noise or grain using an adjustment layer, not scaled, to hide the artifacts.