Bringing-up the Blacks from EX1

MH_Stevens wrote on 2/14/2008, 2:11 PM
I'm finding this issue a little difficult to describe so let me first give the facts of the shoot. It was a very bright high contrast scene. Bright white clouds, white cars, black tarmac, shadows in door way and close-up bushes in full shadow. I exposed about half a stop below clipping so have full detail in the clouds.

As shot the darkest part, the bushes show minimal detail as you would expect and I'm trying to bring out a little of this detail with the Color Curves but here is the problem. The strong blacks cut-off sharply just like they clipped. IE the left side of the histogram has a very high value at 0 (zero luminance) and the drops to nothing. The Waveform monitor has a thick line running all along the 0 bar. Trying to drop the end by the lowest blacks even with very fine adjustment seems to drop all the blacks, not just the very bottom, and produces a lot of noise.

What is happening here and why is the EX1 histogram in bright contrasty scene not like a bell curve that tapers at both ends but like a rectangle where blacks (and to some extent white) drop off like the side of a cliff? With HDV I never saw anything like this as I always had gradual drop-off at each end of the luminance scale. I'm really confused as to just what the camera is recording and to how Vegas seems it. The picture quality unprocessed is superb, I just want to soften contrast to be more film like.

Would capturing with a 10bit codec (like NEO-HD) give me more options?

Comments

Serena wrote on 2/14/2008, 3:28 PM
I think it is very difficult to comment without having the image and knowing the picture profile you've used. The bottom end is controlled by black gamma and black level, which you can manoeuvre yourself in addition to Sony's defaults. It would seem that your setting severely crushed blacks. If you haven't done so I would try cine gamma 4.
MH_Stevens wrote on 2/14/2008, 4:48 PM
Serena:
This was Cine4 gamma, all settings neutral except for HiSAT Matrix, and Black Master -2 and Black Gamma -3. I though my detailed description of the scene would suffice as this is not a special situation - I get this shaped histogram an all my CINE preset shots. If you see some6thing different please advise. I will start a similar thread so I can post a screen shot for you DVi.

This is my attempt to draw the Vegas Histogram: (Can one screen shot a histogram to publish?)

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This Do you see the sharp cut off of the blacks like a black clipping on the left y-axis? CAN THIS BE BECAUSE OF UNDER EXPOSURE?

Michael
Serena wrote on 2/14/2008, 5:57 PM
Michael,
I've had a look at the image you posted at DVInfo and don't see a problem. I haven't loaded it into Vegas, which I can do if that might help. My comments posted at DVInfo are:
"There are a lot of pixels in the black region of the image and that is what the histogram shows; namely how many pixels are at each brightness. The camera histogram puts black a bit to the right of the apparent zero and in an underexposed image you get that cliff at the black end because that's where all the pixels are. If you over expose it becomes a gradual decline because there aren't many pixels that are dark.
In Photoshop your posted image gives the usual histogram I'd expect (there are a lot of blacks present and no cut-off -- apart from a number down at 0) and the amount of detail in the dark hedge is quite surprising (considering the brightness range in the subject). You can bring it up with levels, but that doesn't help the rest of the image. I would use masking to bring up only the hedge using levels, but noise will be a problem with such an underexposed area.
Looks pretty good, to me."