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Andrew Kramer’s 32 bpc HDR tutorial
Hi guys.. i found out about creative cow when looking for after effects tutorials, and i really liked what i’ve seen… when i was watching Andrew Kramer’s tutorial for 32 bpc and HDR images, i was amazed and thought i’d give it a try.. but it looks like it takes a little bit more than just watching the video to learn how to do that!!! i created a comp, a new solid, applyied the ramp effect, and then came back to watch the tutorial… i mean.. i was working in 8bpc, just like andrew in the tutorial… then, he goes to the project settings and then comes back to the ramp setting, and allof a sudden you can see that he is already working on 32bpc… in the info pallete, it shows values like 0.7292, instead of traditional 8bpc rgb codes… please tell me, am i really dumb or is there something that i don’t konw?? whe he goes to change the end color, the window opens and the rgb codes are already 1 1 1… and… well… i didn’t understand how, all of a sudden, it turned to that, so, could anyone out there help me out with this??
by the way, i tryied to do it by myself, but wasn’t able, i went in File > Project Settings
inside that, there was the option to change the depth from 8pc to other things, except it is locked… the drop down menu is locked!!! it also says that the color profile converter could be used to manually convert between color spaces, but i tryied and didn’t get any luck.. besides, i think this is not really the greatest way to do it, so i thought i’d ask you guys around here to see if you could help me!!
sorry for the big post!!!!
tks
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2 Replies
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AE’s 32-bit mode (hereon referred to as HDR) uses 32-bit floating-point calculations. That means that there is an exponentially larger number of values available for the color channels, and a simple numerical scale (8-bit uses 0-255) won’t cut it.
HDR instead uses a scale from 0 to 1.0. Zero represents black, and 1.0 represents white. Values inbetween are represented using decimal values (roughly a percentage, but notice that the precision of the decimal value is very high). Now here’s where the of HDR magic happens: you can have values that are lower than zero and higher than one. This means that you have values that are blacker than black and whiter than white.
How on earth can this be? Isn’t white, well, white? For a computer yes, but computers are limited in the range of colors they can display. HDR is meant to represent the colors of the real world, which a computer can not fully represent on screen. The 0 to 1.0 scale for HDR represents only the values that fit within the computer’s range, and values outside that range are relatively brighter or darker. It looks a little like this:
-…..0…..1…..+
Between 0 and 1 is what the computer can display, but in the real world there’s useful color information outside the range. It might be a very bright reflection off a metal surface, or a very deep shadow in a dark forest. They don’t display on a computer because they’re too bright or too dark. In the past, you’ve either had to clip off those values to white or black, losing the useful color information, or you had to compress them into the computer’s range, which can throw off the overall luminance balance of the image.
HDR provides a new way to access the overrange information. If you adjust the range (using AE’s Exposure effect), like so:
-……..0…..1..+
then you’ll get more of the highlights in the image to look correctly exposed. You’ll lose a lot of the darker colors into pure black at the same time, but it’s one of those artistic choices that you have to make.
I don’t know if I’ve explained this well at all, but those are the basics of why HDR uses a different scale for color and luminance values. The help files for AE 7.0 or Photoshop CS2 have more practical info, and there are plenty of web sites and books out there you can look up. Try downloading some sample HDR files and playing with them in AE and Photoshop CS2 (if you have it). Play with the exposure and you’ll get to see what I’m talking about.
As for your problem with the 32-bit option being grayed out, 32-bit is only available in AE Pro, so it would make sense if you’re using AE Standard.
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hey timothy…. thanks for the great reply… it cleared out some things for me.. i think i had already got this concepts, but this way i’m being able to see it more clearly… and this way i think i should be able to explain it to people (which i think is a very good way to see if you really understand the concept of it!)… thanks very much….
as for the AE being pro or standard, i’m using the trial version.. i guess this means i’ve got the standard.. we’re waiting for our matrox board to arrive, which comes with AE pro, premiere pro 2 and other cool stuff.. i guess until then i’m going to have to agonyze until i’m able to see it on action… i mean.. i really liked the motion blur effect demonstrated on kramen’s tutorial…hope to accquire a lot more knowledge around here!! thanks for you all!!!
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