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.
Rick - as I mentioned before, I've already spent some time investigating this issue. I am aware all of these issues with compressed footage, with compression artifacts, with chroma subsampling and so on. I am so called "professional" filmmaker, who switched from avid systems to adobe from various reasons.
The video is a red raw 444 shot at higher iso - so there is some slight noise but no compression at all. I also, after your opinion, did a testing with a raw photo. Result is the same.
Moving noise does not spread this static pattern. It looks even worse, here is why: this is not a dither random noise which indeed disapears while motion - the artifacts are forms of FPN (Fixed pattern noise) always visible, even worse, because it is an only static impression on screen while everything around moves.
And then - why photoshop does not introduce this pattern while identical scaling is performed? I am sure it is about only two options of interpolation in AE, versus several in PS. Also, software like 3dsmax does not introduce such artifact scaling on textures, where anisotropic filtering is set to maximum. So it can be possible to scale noise without artifacts, it is only the question of algorithm used.
So I cannot click "Correct Answer" under your post, even if I wish the problem could be so easily dismissed.
all the best.
Well, anyone please?
There are some third party scaling plugins that have some different algorithms that may produce better results with different types of footage. The problem with your problem is that there is no one click solution for every instance. Each shot is different and what will work perfectly with one will not work perfectly with another. Sometimes even changing the scale a half percent will effectively hide repeating patterns in the render. Sometimes a shot that has absolutely none of these repeating pattern artifacts when rendered to a lossless format will end up with them when compressed as an MPEG file. The point is, that will a little careful planning After Effects, or Nuke, or Fusion, or even Motion are all capable of producing absolutely amazing sequences and visual effects, but some of those amazing shots can be easily spoiled when played compressed or played back on a different device.
If you have a specific scaling problem that can't be solved in any other way then I would suggest you give these a try. The first one is free:
Red Giant - Products - Instant HD 1.2 (Specifically the Resizer)
RE:Vision Effects, Inc. : Products: SmoothKit (fixes problems associated with all kinds of shots)
There are probably others. I use Red Giant Resizer often
I just noticed the serious scaling artefacts in Photoshop CC 2015.1.2. This is horrible and scary. I will have to review a ton of images. The artefacts are not immediately evident in busy pictures, but in uniform B&W photos, the bug is obvious. To showcase the problem I'm using a grayscale image. I did a lot of experiments and reached to the following conclusions:
- This only seems to be happening with 16 bit images. I cannot reproduce the artefacts with 8 bit & 32bit images in all situations. (but I work entirely with 16bit RAW images as they come like this out of the camera, so this IS a problem for me);
- This only happens when the background is a layer. Even if it's just a single layer;
- The pattern varies - some times its made up of squares, other times rectangles and other times squares & rectangles overlap, like in the examples below;
- If the background is flattened, the artefacts do not occur when resizing (upscaling or downscaling);
- The artefacts are much more pronounced if the rescaling is done to an uneven number of pixels. For example, resizing from 3000pix wide to 2111pix is much worse than resizing to 2000pix;
- The problem appears to be only an "illusion", because when exporting, the preview and resulting JPG's on disk are OK. See images 4A & 4B below. But this is still a problem, because working on files with such overlaid artefacts is very distracting and...scary
Image 1: normal file before downsizing, 16bit (as mentioned, this does not happen with 8bit and 32bit images, nor with flattened images). Background is a layer:
Image 2A: after resizing (Image > Image Size...):
Image 2B: Same as 2A above, but with exaggerated brightness to better show the pattern:
Image 3A: Same as example 2, but slightly zoomed in to show details of the pattern:
Image 3B: Same as 3A above, but with exaggerated brightness to better show the pattern:
Image 4A: On export (Fale > Export > Save For Web (Legacy)...) the preview is OK, but notice the original file behind the dialogue window is not OK:
Image 4B: Same as 4A above, but with exaggerated brightness to better show the pattern:
That's all for now. I hope Adobe will look into this issues.
KDL [at] angolaimagebank.com
Yes, and that's what I was talking about - all apps like premiere pro CC, after effects CC and Photoshop use the same scaling alghoritm. Making noisy image bigger like 102.5% for example introduces grid like pattern on the whole frame. It's not visible on casual photos, but if you have frame with lot of noise like 35mm tape scan in movie, they become visible in cinema. Very strange. I use instant 4k, but not always there is time for doing this.
Adobe guys, any word about it?