Tag Archives: banding

HELP! There is banding in my footage – or is there?

I’ve written about this before, but it’s worth bringing up again as I keep coming across people that are convinced there is a banding issue with their camera or their footage. Most commonly they have shot a clear blue sky or a plain wall and when they start to edit or grade their content they see banding in the footage.

Most of the cameras on the market today have good quality 10 bit codecs and there is no reason why you should ever see banding in a 10 bit recording, it’s actually fairly uncommon in 8 bit recordings unless they are very compressed or a lot of noise reduction has been used.

So – why are these people seeing banding in their footage? 

99% of the time it is because of their monitoring. 

Don’t be at all surprised if you see banding in footage if you view the content on a computer monitor or other monitor connected via a computers own HDMI port or a graphics card HDMI port. When monitoring this way it is very, very common to see banding that isn’t really there. If this is what you are using there will be no way to be sure whether any banding you see is real or not (about the only exception to this is the screen of the new M1 laptops). There are so many level translations between the colourspace and bit depth of the source video files, the computer desktop, the HDMI output and the monitors setup that banding is often introduced somewhere in the chain. Very often the source clips will be 10 bit YCbCr, the computer might be using a 16 bit or 24 bit colour mode and then the  HDMI might only be 8 bit RGB. Plus the gamma of the monitor may be badly matched and the monitor itself of unknown quality.

For a true assessment of whether footage has banding or not you want a proper, good quality video monitor connected via a proper video card such as a Blackmagic Decklink card or a device such as a BlackMagic UltraStudio product. When using a proper video card (not a graphics card) you bypass all the computer processing and go straight from the source content to the correct output. This way you will go from the 10 bit YCbCr direct to a 10 bit YCbCr output so there won’t be extra conversion and translation stages adding phantom artefacts to your footage.

If you are seeing banding, to try to understand whether the banding you are seeing is in the original footage or not try this: Take the footage into your grading software, using a paused (still) frame enlarge the clip so that the area with banding fills the monitor and note exactly where the edges of the bands are. Then slowly change the contrast of the clip. If the position of the edges of the bands moves, they are not in the original footage and something else is causing them. If they do not move, then they are baked in to the original material.

Why you need to sort out your post production monitoring!

One of THE most common complaints I hear, day in, day out, is: There is banding in my footage.

Before you start complaining about banding or other image artefacts ask yourself one very simply, but very important question: Do I know EXACTLY what is happening to my footage within my computer or playback system? As an example, editing on a computer your footage will be starting of at it’s native bit depth. It might then be converted to a different bit depth by the edit or grading software for manipulation. Then that new bit depth signal is passed to the computers graphic card to be displayed. At this point it will possibly be converted to another bit depth as it passes through the GPU and then it will be converted to the bit depth of the computers desktop display. From there you might be passing it down an HDMI cable where another bit depth change might be needed before it finally arrives at your monitor at goodness knows what bit depth.

The two images below are very telling. The first is a photo of a high end TV connected to my MacBook ProRetina via HDMI playing back a 10 bit ProRes file in HD. The bottom picture is exactly the same file being played back out of an Atomos Shogun via HDMI to exactly the same TV. The difference is striking to say the least. Same file, same TV, same resolution. The only difference is the top one is playing back off the computer, the lower from a proper video player. I also know from experience that if I plug in a proper video output device such as a Blackmagic Mini-monitor to the laptops Thunderbolt port I will not see the same artefacts as I do when using the computers built in HDMI.

And this is a not just a quirk of my laptop, my grading suite is exactly the same. If I use the PC’s built in HDMI the pictures suck. Lots of banding and other unwanted artefacts. Play back the same clip via a dedicated, made for video, internal PCI card such as a Decklink card and almost always all of the problems go away. If you use SDI rather than HDMI things tend to be even better.

So don’t skimp on your monitoring path if you really want to know what your footage looks like. Get a proper video card, don’t rely on the computers GPU. Get a decent monitor with an SDI input and try to avoid HDMI for any critical monitoring.

20170620_091235-1024x576 Why you need to sort out your post production monitoring!
Shot viewed on a good quality TV via HDMI from the computers built in graphics card. Notice all the banding.

20170620_091347-1024x576 Why you need to sort out your post production monitoring!
Exactly the same shot/clip as above. But this time played back over HDMI from an Atomos Shogun Flame onto the very same TV. Not how all the banding has gone.