? pixeled image

story2rewrite

story2rewrite

Well-known member
Howdy. I'm new to the 5d coming from the t2i. I had a night shoot with 2 candles and 2 arri lights and a natural flickering to represent the flicker of the candle with umbrellas for fill on her face. Hot and cold. I notice this banding where the candle hits the wall and pixels scattered. Is this normal? Do I need to use a faster lens? I used a helios 2.0 wide open. The room was pretty well lit. Any advice for future shooting?

Here's the clip. I messed with color too but that makes the problem worse...

http://www.youtube.com/watch?v=MCo7oIICHCE
 
I would be curious for the replies. I got the same things here at 21 in the girls shadows.

I think the reason that it happened to me is because I should of over lit the scene, filmed and then brought down the brightness in post. I was disappointed...
 
Looks like the usual color space banding to me. Candle shot you could mask. Always always edit intermediate (unless you're on prem. CS5).

"I messed with color too but that makes the problem worse". Well again get into 10-bit. Also you will want to check out the (quite amazing) technicolor profile. But yeah i would try masking that wall.
 
Yeah. I love the technicolor. This was before it came out. I do use cs5 with an ample pc. Loving it. I use the native files and bring into premiere which is supposed to automatically up the color space. Then I bring into after effects using dynamic link to create a new composition and up the bpc there. It works great but I wasn't sure about the banding issue. I only saw it in low light. I'm wondering how people get footage of just a lighter or candle and having this great looking image. I had several light sources and still got banding. Maybe it was the flickering flame. Or is this usual. Just trying to figure it out. Next time maybe I'll blast a light on the wall as well and then lower in post.
 
story2rewrite said:
Howdy. I'm new to the 5d coming from the t2i. I had a night shoot with 2 candles and 2 arri lights and a natural flickering to represent the flicker of the candle with umbrellas for fill on her face. Hot and cold. I notice this banding where the candle hits the wall and pixels scattered. Is this normal? Do I need to use a faster lens? I used a helios 2.0 wide open. The room was pretty well lit. Any advice for future shooting?

Here's the clip. I messed with color too but that makes the problem worse...

http://www.youtube.com/watch?v=MCo7oIICHCE
Click to expand...


This is normal for youtube; but the question is how "bad" was the original footage ?
 
It's not just youtube. Same thing when I burn dvd as well. The original footage has the problems too. Just wondering if this is something normal. Any good steps to prevent it in the future? Helpful tips?
 
story2rewrite said:
It's not just youtube. Same thing when I burn dvd as well. The original footage has the problems too. Just wondering if this is something normal. Any good steps to prevent it in the future? Helpful tips?
Click to expand...


Yes it's "normal." But I seriously doubt the original footage is as bad as the youtube video. It can be "normal" for DVD as well, if you don't prepare it properly.

The underlying problem is poor compression and an 8bit format. Poor DSLR compression, poor youtube compression, poor MPEG2 compression for DVD. Since you said the original had problems as well, throw in inadequate preparation and encoding .

But it's possible to work around some of these issues with proper filtering and dithering , using a good encoder with adequate bitrate. This practically rules out youtube, possibly DVD, but it's "doable" on blu-ray or web if you do your own hosting , but the bitrates required aren't "streaming friendly" (usually NOT possible youtube or vimeo because bitrates are too low, or in very rare circumstances) . Even if you fix it in post, it will become blocky again when uploaded to youtube because the compression isn't good enough to retain the dither.

Not much you can do on the acquisition side, besides use brighter lighting , faster lenses, better compression or different camera. Blacks (low luminace areas) are heavily quantized by the Canon DSLR compression , but the youtube compression exacerbates the issue immensely. This is one strategy that codecs use to improve compression - the thinking is foreground subjects like actors faces etc... are more important than the background, so bitrate is distributed accordingly. This is why you so often see "mushy blacks" or poor detail in shadow areas - the average Mb quantizer is high in those areas


Here is a 360p example to illustrate, I took the blocky youtube video and fixed it up, dithered, and prepared it properly.

http://www.blip.tv/file/5127709


So what's the catch? If you examine it more closely and look at the average bitrate - the youtube video was about 300kb/s, the filtered video is about 4000kb/s. Huge difference. If you were to upload that video to youtube - it will become blocky again when youtube butchers it. (Of course you would get better results if you started from the original footage, instead of the crappy youtube video.)



Bottom line - you need to use better pre-processing , better encoder, higher bitrates
If you want more info on dithering and pre-processing, do a search on this site, I've made several posts about this.
 
Fine gradient shots are tricky for these cameras basicly. Our low-end LCD/tft computer monitors also expose problems that may not be visible on other formats, like CRT or actually any form of projection... it tends to look fantastic.

So... the gradient breakup will occur on the web and people won't notice it/expect it cus web quality is still relatively poor and "that's how it looks", if you would show it projected on a screen however it would likely not be as pronounced, or even seen at all. Really, there are so many factors at play in the end.

Myself i've gotten extremely annoyed with almost every shot from any of my 8-bit cameras & seeing banding all over the place....... you kinda have to resist the "dark side" of pixelpeeping..... and put your mind to the content.
 
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