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What is a bleach bybass?

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Bette CraigWhat is a bleach bybass?
by on Jul 13, 2001 at 3:38:03 am


My boss just asked me to do an effect simulating a bleach bypass. I nodded confidently, but quite frankly, I hear that term all the time, but I don't know what it means.

Can someone explain what the term means, and give me a few hints how to do it?

Please. Of course, I have this deadline.

Bette C.

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Chris ZwarRe: What is a bleach bybass?
by on Jul 13, 2001 at 8:35:31 am

Bleach bypass is a film processing effect that in simple terms doesn't wash excess silver from the emulsion.

Basically this means you get really dense blacks.

I haven't seen the movie "Three Kings" but apparently the directors commentary contains a lot of detail about the bleach bypass system used on the film, which gave it a very unique look.

To simulate the effect with video, the first stop would be your levels filter, and try notching the "input black" up, and maybe slightly lowering your gamma a bit, maybe .9 or so.

Then duplicate your layer and add a blur effect, something around 10 pixels. Hopefully you have either a fast machine or a fast blur algorithm (eg. Tinderbox or a Puffin blur) or even both. Then change this upper layer to the screen transfer mode.

If you leave it like this you have a glowy music video effect that I use a lot to make crap footage look good. But by doing hardcore levels adjusting on the screened layer you get some excellent color effects.

So on your upper layer, the one with the screen transfer mode and the blur, alter the levels filter so the input blacks are something much higher, eg. 90, and your input white is down to about 200. Try adjusting the individual colour channels to achevie an "earthy" look - lowering the blue gamma will often do this, but you don't want people going yellow. You may need to lower the overall opacity of the layer if it's not working, 60 - 70 % may look much better.

Finally, add an adjustment layer to the lot and bring your levels back to video legals, if you're using video. Your colours may be too rich so the HSL filter can be used to desaturate the overall effect, and you may want to swing the hue around a few degrees to the left to compensate for the screen transfer mode.

Overall, this recipe will smooth out your image and remove grain, crush the blacks and increase contast to create a denser image, and give the image a soft, diffuse look (and desaturated if you choose) that isn't the same as shooting film but definitely not video.

Good luck.

Chris Zwar
Entertainment Media

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Donat Van BellinghenRe: What is a bleach bybass?
by on Jul 13, 2001 at 6:06:46 pm

Just to add to Chris explanation : When processing a color negative film, one step is to remove the silver grains (bleaching), so that only the color remains in the emulsion. When you skip this step, what you get is a mix between a black and white image and a color image, so I would try the follwing method to simulate it using AE : Duplicate your footage layer, then desaturate the top layer, swith its mode to multiply or overlay, and maybe add some film grain on the top layer.


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Bette CraigRe: What is a bleach bybass?
by on Jul 13, 2001 at 8:16:28 pm

Thanks for your great answers. You really helped explain the whole concept instead of just telling me how to do it. You should write Kathlyn, this would make a great article for the cow library.

Bette C

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Chris ZwarRe: What is a bleach bybass?
by on Jul 14, 2001 at 12:01:44 am

I'm glad you find it helpful...

I was thinking about this a lot last night because, like yourself, I often hear the term "bleach bypass" thrown around but from what I can tell, not many people (here is Australia anyway) actually do it chemically, most seem to "simulate" the look in colourgrading etc. So you end up with a whole lot of people copying a "bleach bypass" look which was never bleach bypass to begin with....

One thing I have noticed is that the look can be varied quite a bit, and the sorts of people who use a bleach bypass system are also the sorts of people to do hardcore colourgrading and use lots of other effects, so where the bleach-bypass ends and the colour-grading begins is a little indistinct.

I've only got one TVC on my shelf which I know for sure was a "proper" bleach bypass done at a lab, and finished on film. It does indeed look like a mix of black and white with colour, but it also has really strong earthy tones to it. It also looks quite different to "Three Kings", which is the only film I know of that used bleach bypass, although I haven't seen all of it.

In addition to the steps I suggested earlier, you could try adding a third layer on top (but under the adjustment layer) that was tinted sepia, and mixing this in with a very low opacity.

I'm going to go back to that TVC and have a much closer look at the way it has come out, if I can find a recipe that replicates the look then I'll write a short article for Kathlyn (famous last words).

And you could also just hire "Three Kings", which I'm told is pretty good.

Chris Zwar
Entertainment Media

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J.R.EllisRe: What is a bleach bybass?
by on Jul 15, 2001 at 1:49:03 am

We used true bleach bypass on the film PYTHON on the mutant snake's pov shots ('s out on dvd (and doing quite well!)...I used After Effects NT extensively for compositing on that project (all 2k files), tho Digital Fusion played a big compositing hand and the snake was almost all Maya ;)

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John FischerRe: cool look
by on Jul 16, 2001 at 3:56:21 am

Chris --

I tried out your recipe .. it's pretty cool. Similar to "Three Kings" but not .. I'm guessing the footage you use makes a big difference too (in terms of colors, etc...) in the final look.


John Fischer

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