TVP to DCP, anyone?

[slowtiger]

I wonder if anybody already has experience in creating a DigitalCinema Package (DCP) from a TVP project. I'm researching about digital cinema recently, especially to collect knowledge about what to do, where to search, and how much to pay.

Right now I'm delving in technicval specs a lot. In a document from Dolby about the requirements for material sent to them to be processed into a DCP it reads: "Pixel components shall have 12 bits of depth and shall be stored in the slice using 16 bits per component (12 bits plus LSB pad of 4 zero bits)." Now this is clearly more bits than the 8bit per channel TVP supports.

Has anybody already transferred a film to DCP? If so, what are the experiences? Did anybody complain about images being only 8bit per channel, or sound being only 16bit?

[Paul Fierlinger]

I had to read up on this subject after I read your post. All I can say is that my producers are certainly planning to release My Dog Tulip in this technology, first in the UK and then the rest of the world. This should be happening about a year from now. They want to wait to first enter the movie at Cannes next May before they make a public release. Only then will I be able to answer your question.

[User 767]

DCP standards allow for maintaining quality available right now (in theory). They talk about what the system should be capable of delivering, not what you need to supply. I believe the specs cover 3D projection, and high frame rates as well.

The conversion to DCP from original includes a color space modification (different LUT), as well as 'tweaking' contrast for a decent looking 'projected' image. So, 8 bit color doesn't leave much room for those 'shifts' to occur quite as smoothly. The more information you can deliver, the better. With an 8 bit image, you might expect to see some issues in shadow and highlight areas staying 'clean' (banding, muddiness, blocking, etc.). Naturally, all of that depends on the original image, it's tonal range, and the person who's encoding it. [In theory], the digital release version should look like the film version.

I'd suggest you contact an encoder, and ask them what they would like, and what they can best deal with. Barco is in Belgium: http://www.barco.com/ (somewhat closer to you than Hollywood) Or, read on;

Paul, you're using Pacific Title, right? They do DCP there. Have you talked to anyone about that conversion yet (or is that going somewhere else?). (Probably Marc Ross?) If they're already doing the film recording, they can probably give you a pretty good idea of how what will work for digital. What file format have you been supplying?

http://www.pactitle.com/
http://www.kodak.com/US/en/motion/hub/dcinema.jhtml
http://www.qubecinema.com/
http://www.technicolor.com/Cultures/En- ... +Servi.htm

No, I haven't done DCP (DCDM) from TVP. Film, yes.

[Paul Fierlinger]

Us 7,

I haven't even begun to think about this aspect of the delivery process. We have decided to look into Shooters, in Philadelphia, at this point and I'll go from there.
http://www.shootersfilms.tv/directions.html

They have a good reputation with lots of new equipment and I even know some of the guys who work there from my old film days. I need to start with some face to face talk, so I might as well start on home turf for that.

[slowtiger]

767: I'd figured out that much as well. The least result I expect would be that the 8bit/channel images I can render (in TVP or else) are converted the best possile way into that other color space. From my experience with printing etc I don't expect much problems in image quality within the style of animation I do, or Paul's.

The only tricky shot would be if someone uses very flat gradients over long distances - this could cause banding on the screen, like in printing. And I think one could heal this with applying some noise filter over the final render - maybe not the normal variant, but some special film-grain like filter.

[Paul Fierlinger]

STig,

you make a good point about large flat areas. Whenever that happens to us, both Sandra and I discuss what should be done to disrupt the flatness without making it look too digitally dithered. We weren't aware of the technical liabilities you just brought out here; we were just intuitively displeased with the CG look of flatness.

For conversion to film I guess the best advice would be to stay away from the fill bucket for large, static areas.

[slowtiger]

You will not have any problem with an area which is of one uniform colour. Problems could only occur with very flat gradients, that is, something like from dark blue to a bit not so dark blue, but over the entire width of frame. I've also noticed (in doing print jobs) that a not-quite-so-accurate retouching, like painting some area in an otherwise uniform area with a just slightly different colour, impossible to spot with a naked eye, could be amazingly visible in print.

The filter I've mentioned needs to be able to create a "stochastic noise pattern", which means it will translate each colour level into a small range of levels which get spread over an area most randomly. This way the border between one colour level and the very next is broken up and made invisible. There were filters available for Photoshop 10 yrs ago when "stochastic rasters" were pretty new, but I haven't searched about that topic since. If necessary, I'll do.

[slowtiger]

Just did a little test. The first image is a 10% reduction of an 1920 x 1080 image with a very flat gradient (#3366ff to #3399ff) from top left to bottom right. I did it once in Photoshop CS3 and once in TVP, using the exact same colours.

sky1.png (5.56 KiB) Viewed 28554 times

The second image is an enlargement of a detail, showing only one channel, once normal values, once with enhanced contrast to make the difference visible. You'll notice that (at least the new version of) Photoshop already does a stochastic spread of values. This is nice to know (I just learnt it). TVP does the gradient the easier way, just spreading values uniformly over distance, which results in banding.

sky_detail.png (8.87 KiB) Viewed 28554 times

I don't say that this banding must be visible on screen - this largely depends on how the conversion from TVP rendered images to DCP is done. Maybe they already apply some filter? I don't know.

This is why I appreciate a slightly visible texture so much: it will nearly always cover banding. If I use large gradients, like sky, I think I will do them in PS and import to TVP. All my other colour areas will have some structure in it.

[User 767]

I had a long discussion today with a technician at Technicolor about DCP. He showed me some stuff that was very informative.

Here's what I got from my visit: Large flat areas like sky start to fall apart quickly. DCP uses JPEG compression, and it doesn't deal well with that. I questioned whether or not it was the smooth gradient that was the problem, and got a demonstration. Looks like big flat areas show compression artifacts fairly easily. Same goes for things like credit rolls and still frames. A frame that's a solid color will compress differently from frame to frame-thus artifacts.

Delivering anything less than a 10 bit DPX file should get you some disclaimers about image quality. Cel-style animation brings some issues with it. Most of the issues have to do with compression artifacts-which show up because there's generally not enough happening to hide the compression. I hadn't realized that Digital projection uses the same data rate for 2K and 4K projection. So, your theoretically higher resolution digital projection is more compressed.

Suggestions: test images by looking at still frames converted to GIF 64 for a worst-case idea. Convert and tweak images by running them through something like GraphicsMagick : http://www.graphicsmagick.org/ Conversion is to DPX 10 bit Log or better files. In this way, you have some control over what direction the image will go for it's projection conversion. The conversion and filtering lets you see what's going on, and lets you adjust for it.

I have pages of notes. There's probably something else I forgot to write here.

[Peter Wassink]

Slowtiger, this excact topic (with almost identical image) was just recently discussed in the Betaforum.
Check out your Gradient panel, it has a 'spread' option,if you set it to 2% and you have you PS gradient.

oh...and the 2% spread will become the new default

[slowtiger]

Tantalus: Good news! I figured it couldn't be such a big deal to incorporate this. (BTW Photoshop sneaked this in over the last versions. They also changed their airbrush to the same effect. This is kind of a full circle: the drawing tools in v4 acted very "painterly", then from v5 on in went worse, with now being in v10 they try to be "organic" again ...)

767: Isn't it funny that it is so hard to maintain the established quality of 35mm film in the digital domain? Everytime I spot artifacts in an animated movie I cringe. I also spot them in life action, though none of my friends does (anymore).

One could, just for fun, define the specs for an artifact-safe movie ... "NTSC colours only ... no uniform colours anywhere ... all pans and other movements must be done in multiples of 8 px ... no more than 20% of the screen shall be moving at any given moment ..."

[Paul Fierlinger]

This might explain a lot too:
http://www.youtube.com/watch?v=YvZZNwDnJuk

[slowtiger]

Made my day, thx!

[Paul Fierlinger]

I found the evaluation of rotoscoping towards the end quite accurate...

[Sierra Rose]

Yes I thought of you in the part about rotoscoping. Very funny.