whoa. not cool. anamorphic/double squeeze high contrast...

madbunny

madbunny

New member
hey all,
got some dvx problem child footage.
shot with an anamorphic lens, with the squeeze function enabled under theatrical lighting instruments.
problem is these high contrast color intensity shifts eg. the red v.s. greens and white v.s. either red or green.

the top finger points to a flower which is green. ya know, like the other green flowers.


shimmyproblemdetail.jpg


the big problem is this vertical striping. how the potatoes do i get rid of this/ never see this in my footage again?

shimmyproblemlarge.jpg
 
You have fallen into the classic trap of the limitations of NTSC.

Here is some information I extracted from the following URL: http://www.utoronto.ca/cat/services/services_other/videoTips.html

This explains what's going on here:

# Use colour with video in mind

NTSC video has very low resolution for colour. The NTSC standard was designed to be compatible with black and white television. The luminance part of the NTSC signal, is essentially just the old black and white television signal. The colour information was added to it on two "chroma" channels, but with the broadcasting technology of the time there was a limitation on the total bandwidth of the signal. As a result, the resolution of the colour signal was compromised both in the colours that can be represented and in spatial resolution.

1. Avoid bright and saturated colours

Colours that cannot be represented tend to confuse the circuitry which generates an NTSC signal from an input image. As a result they tend to look "alive" on a video. Colours which are saturated and bright are likely to cause problems. If red is used, the colour artifacts will be more severe. Darker, and less saturated (pastel) colours tend to display better on NTSC, and if you must use red, use a low intensity red.

2. Avoid high contrast images with sudden colour transitions

Rapid colour transitions cannot be represented in NTSC video because of the low spatial resolution of the colour part of the signal. One of the visible consequences of this is an effect called "chroma crawl" visible around high contrast edges in an image. Anti-aliasing images or even blurring them slightly will reduce this undesirable effect by smoothing the colour transitions in the image making them easier to handle.

Chroma crawl can also be reduced by choosing colours that lower the contrast in an image. For example, brightly coloured objects on a black background will cause chroma crawl. This can be reduced by lightening the background, and/or reducing the brightness of the objects.
 
so essentially this falls into the category of "video sucks".
must be the extremely small amount of bandwidth real estate between R and G on the chroma.

now,
question #3:
can i expect to lose some of the definition of the vertical striping on the export and playback in analog on a projection tube?
if i can get to haloing instead of "video tweed" i would be less likely to punt every video camera i see for the next several months...
 
The vertical striping you're seeing is the lovely 4:1:1 colour sampling. The fact that you've anamorphically stretched the image makes the effect even worse.

To improve the look of the image a little bit, you can horizontally blur the chroma channels.

-Spiff
 
Just out of curiosity, why are you using a combination of anamorphic lens and squeeze?

This will give you an aspect ratio of approximately 2:35:1

You will gain more resolution by shooting without squeeze mode and letterboxing on a 16x9 timeline. It will also render faster. Your NLE currently will need to resize your footage to fit your timeline because there is no native Cinemascope aspect.

Not trying to tell you how to do your work but it seems like you are losing more than gaining here.
 
this is part of a series of 52 shorts we're making this year whereby we try to tweak the bejeezits out of video.
the final on this project is gonna be fairly low res e.g. ipod video, web video, press kit, etc.
so the 2.35 is more a style function.
anything we can to break the conventional expectations (just need to try a little harder to make sure it doesn't look like poo)

i may even leave the final midly squeezed in homage to all the aspect ratio problems of the world past and present.

my main focus is studio art, composing for theatre and film and graphic design so i overreached a touch on my second go behind the lens...
 
Spiff_2 said:
The vertical striping you're seeing is the lovely 4:1:1 colour sampling. The fact that you've anamorphically stretched the image makes the effect even worse.

To improve the look of the image a little bit, you can horizontally blur the chroma channels.

-Spiff
Click to expand...

thanks spiff!
this was sort of my gut instinct, this or a mask of some sort?

i've also been reading that dv camcorders do a reverse gamma push at the play head to compensate for the weak middle gamma of tube projection. how big a factor is this here?
 
It will also render faster. Your NLE currently will need to resize your footage to fit your timeline because there is no native Cinemascope aspect.
Click to expand...

I'm not sure how this can be done in Premiere, but in After Effects you can make custom pixel aspect ratios, and could certainly make 1.567 aspect by tweaking the perferences file. I had to do this back in the early days of HDV so that I could work with the 1.33 aspect.

Incidentally, I don't know how to blur the chroma channels only and leave the luma channels intact in either Premiere or After Effects... does anyone have instructions as to how this may be done? It seems to me a guaranteed meeds of improving 4:1:1 images for not only keying, but virtually all rendering.

-Spiff
 
In AE you can duplicate the footage, give it a horizontal blur and then set its blending mode to 'color'. =)
 
its like the shot in November when C. Cox was working in the darkroom. Very red, and the footage came out BAD. At first I thought it was an intentional filter, but aft the audio commentary, found out it was

NTSC+MINIDV+RED=:(
 
hey all,

several different attempts at correcting the problem footage met with different levels of success. none where considered valuble enough to warrant the fuzzy/blurry nature of the resolution which occurred.

so in the end i just cut the damned thing and crushed it down to ntsc so you don't see it much. on tvs and projectors it's much less noticable than the powerbook floating around on stage...
:Drogar-BigGrin(DBG)

WARNINGS!

this footage is Quicktime only!

QT for windows is none too happy with this file and most users are reporting audio only.

i've been unable to determine if this is because i dropped the frame rate to 15fps/with keyframe every 15 or whatever the case. if anyone has any insight, splash.

the file is huge 150mb+ and my server is not too fast. expected d/l time is in the range of 9-15 mins on fast dsl.

this video was shot for a whopping 150 dollars. space was donated by a local theatre as were the lights. dvx was already owned by the camera man. i did concept and set design. wrote or co-worte all the music. i did costumes with the bassist. my crew helped me with the set build. and all of my actors are pro/am and donated their time, for which i am eternally grateful. the flinstones clip is an actual clip from the days of sponsorship. i'm expecting my cease and desist from disney or universal or whoever any day now...
 
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