Blue glow artifact around edges, how to get rid of it?

[Graham Bernard]

[Jaanus Henno] “But after rendering it shows a blue glow on an edge of book the subject holds in hand. Why is that and how to remove it?”

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A] What is inside your MPG?

B] What are your Project Settings?

C] What Render Template are using?

Blue fringing indicates a too low or inappropriate colour space and render template is downgrading the colour sampling. You could be rendering to a lower a bitrate or colour space.

Next question: How are you monitoring the output? Back in Vegas? Or where, or on what?

Cheers

Grazie

Video Content Creator and Potter
PC 7 64-bit 16gb * Intel® Core™i7-2600k Quad Core 3.40GHz * 2GB NVIDIA GEFORCE GTX 560 Ti
Cameras: Canon XF300 + PowerShot SX50HS Bridge

[Jaanus Henno]

A) From Mediainfo:
Video
ID : 224 (0xE0)
Format : MPEG Video
Format version : Version 2
Format profile : Main@Main
Format settings, BVOP : Yes
Format settings, Matrix : Custom
Format settings, GOP : M=3, N=12
Duration : 18mn 7s
Bit rate mode : Variable
Bit rate : 4 090 Kbps
Maximum bit rate : 7 700 Kbps
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.394
Stream size : 530 MiB (92%)
Color primaries : BT.601 PAL

B) Upsampling with BCC Uprez to 720×1280. Rendering into Mainconcept Mp4 Iphone template with 25 frames as in the input video.

And actually now it’s getting interesting. First, I realized that the input material also has the blue fringing already, it’s a lousy material. But when I play it back on my external monitor, then it’s practically disappearing, while on my laptops screen it’s quite visible.

[Dave Haynie]

What was this shot with? Blue or Purple fringing is often the result of de-bayering. When you shoot with a single sensor cameras, there can be a color interpolation error around borders.

When you upscale, some algorithms look to follow, smooth, and enhance borders in your image, in order to make the upscaling cleaner. So it’s quite possible the upscaling is enhancing just that part of the original video you don’t particularly want enhanced.

-Dave

[Jaanus Henno]

I see. Thanks Dave.

I wonder, is there a way to remove it?

[Dave Haynie]

No easy way that I know of… that’s why we pay more for 3-chip cameras, or DSLRs and other large sensor cameras — if you have at least 3x as many pixels on the sensor as in the video frame (eg, 6Mpixel or more for an HD frame), pixels can be “bucketed” for RGB, rather than interpolated, eliminating those fringes.

If the color is distinctive enough if your video, you might try some color correction. The problem there is that you might have fringing along any high-contract line, but the color you’d like to fill in for the blue/purple isn’t necessarily the same everywhere in the frame.

Another idea I got from a Photoshop trick for removing chromatic aberrations (see here: https://nicolesyblog.com/2010/06/25/two-minute-tip-removing-chromatic-aberration-in-photoshop). Double your video track, and apply a gaussian blur to the top, just enough to kill the fringe. Photoshop uses a color compositing mode, but there not built-in compositor for that in Vegas (BCC’s RGB compositor, maybe, if you have BCC). You might take the edge (sic) off it by just making that blur layer transparent until the fringe just becomes noticable, then back off, but it will soften the overall video. I’d try BCC’s DV fixer too, just to see what the would do.

There’s another photoshop technique for this using an adjustment layer, but that’s not an option in Vegas.

You might do something with edge detection and masking, but that’s an even higher-level trick… just thinking “out loud” the kind of things I’d try.

-Dave

[Jaanus Henno]

Thanks.
I happened to try Chroma Keyer and voila! Took all the blue out;-) But I can actually do that since there’s nothing significant for the blue to stay. I’m still playing around, probably cookie cutter can be used to just select the part initially intended to. It’s just that taking it all out looks very good, I didn’t realize that there’s a blue tinge on the whole picture, and in that particular case can be done in that way.

Appreciate your help. And while trying double track trick as you suggested, stumbled onto an other option which might be useful in the future. Instead of BCC’s RGB compositor (btw, I do have BCC, but there’s no such effect as RGB compositor, are you sure that this is the exact name?) I used BCC’s Chroma Key on top layer. It has more options that Sony’s and I managed to tweak it to actually remove the fringe but leave blue colors blue. I just wanted to take out the rest of the blue hue also and therefore went with sony’s chroma keyer.

[Dave Haynie]

Great! I had originally thought about recommending chroma keying, but that’s very content-specific; if you have that color anywhere else in the video, you may have some serious masking to play around with. And the key quality could be an issue — I’d trust BCC’s keyer, but the Sony keyer is less flexible.

You only see the BCC compositors when selecting “other” for the compositing effect between a compositing pair — it’s not stand-alone effect. There are half a dozen BCC compositors, and a few Sony plug-in compositors, in addition to those built-in on Vegas (add, multiply, screen, etc). I haven’t used them extensively.

-Dave