Entries in Colorspace (1)

Tuesday
Dec042012

Pitch Perfect takes advantage of P3 Colorspace

Anna Kendrick stars as an alt-girl out of her element when she joins a prissy college a cappella group obsessed with winning the finals in the film, Pitch Perfect.  The film, which also starts Brittany Snow, Anna Camp and Rebel Wilson, has been an indie hit for Universal Pictures and Gold Circle Films.

Colorist Leandro Marini walked director Jason Moore (the Broadway smash Avenue Q) and DP  Julio Macat through the brave new world of DCI-targeted color workflow using the Scratch system.  The film was shot digitally on the Arri Alexa camera to LogC Prores 444 Quicktimes.

For a peek at Pitch Perfect, check out the trailer.

Targeting the DCI-P3 color spec, which is the native colorspace for digital cinema projection, allows for a much wider contrast and color gamut than a traditional film-targeted workflow, and we took full advantage of that for this film.  The highlights of the film take place on a colorful stage with moving lights and flashy performances.  With all the saturated blues and reds, film prints can’t always handle that kind of rich color detail.

This a good moment to pause and talk about colorspace.  People use the term in various ways, but to understand colorspace you have to understand an image’s function in the world.  Colorspace, at its core, concerns itself with the display device that is showing your image.

The first rule: grade your film to natively match your primary distribution format.  These days, that is digital projection and DCPs (Digital Cinema Package).  It is now estimated that 80% of the world’s screens will be digital by the year’s end.  A wide domestic release now only prints a couple hundred film prints for US theaters, in contrast to a couple thousand DCP’s.

A digital image on a hard drive doesn’t technically have a colorspace until it is displayed on a screen.  How that image data looks when it is output to that screen defines its colorspace.  Therefore, on a disk, the digital data that defines color is only an abstract mathematical concept.

The basic colorspaces used in post production are these:  High Definition monitors (Rec.709), Standard Definition monitors (Rec.601), Digital Cinema Projectors (DCI-P3) and Cineon Log for film prints.  If your image “looks good” on an HD monitor and reflects the creative intent of the film, then that image is in the Rec.709 HD colorspace.  Same with P3, if your image looks great, as the creatives intended on a DCI projector, then your image is in the P3 colorspace. On the other hand, if you look at a P3 colorspace image on an HD monitor, it will look too bright, and colors that are heavily saturated will start to bleed out and lose definition.  If you look at an HD colorspace image in P3 mode on a DCI projector, it will look too flat & dark and not take advantage of the richly saturated colors available to you.

There often isn’t metadata in the image files to tell you what colorspace was intended in the grading suite, so be sure to label everything properly.

The second way that the term colorspace is used, I think is a misnomer.  If someone were to describe colorspace as 4:2:2, 4:4:4, RGB, YCbCr (aka YUV) or XYZ, then what these refer to is different ways to numerically represent color data in an image file.  They don’t inherently describe the color properties of a display device, but simply the data format that the signal is in.

You can have a digital image intended for HD monitors (Rec.709) that can be encoded in any of the above formats and there aren’t any significant color value differences.  Each of those formats are designed for different uses:  4:2:2 YCbCr for HDTV, RGB 4:4:4 for color critical monitoring, and XYZ for digital cinema.  The technical differences between them we’ll save for a more detailed article.

To further understand the distinct physical differences, below are a few stills.  Keep in mind that your computer monitor is in the sRGB colorspace, so none of these images will look as the creatives intended, but you get the idea.

Here is the final grade in DCI-P3 RGB:

P3 uses a native gamma encoding of 2.6, a perceptually brighter image, in order to show more detail in the blacks. It also has a white point that is perceived as green when viewed on an HD monitor.  Overall it has the ability to show more saturated colors in the spectrum, as demonstrated by this graph below comparing HD to P3:

 

 

 

 

 

 

 
Here is the transformation of that image to Rec.709 HD (RGB):

In order to remain in “legal” HD color levels for the home video version, some saturation has to be dialed out of the P3 image, and an overall shift toward magenta to make the white’s not so green.  HD has a native gamma of 2.2 (or 2.35), which leads to a darker image.

Here is what a “cineon log” curve encoded image looks like, with its color and contrast transformed to look good when printed to a release print film stock:

Here is what an XYZ translation looks like, but still in DCI-P3:

 XYZ is a different mathematical color plotting all together, representing axis on a color gamut chart (see above), rather than actual colors themselves.  Your monitor is showing the X value as “R” the Y value as “G” and the Z value as “B,” so there’s no way it’ll look anywhere close to a correct image in your browser.  This, however, is the highest standard of color representation, thus the choice for digital cinema projectors worldwide.

In addition to the color, we at Local Hero had fun using extra VFX style tools available in Scratch, for beauty work, clean-up and enhancing reality.  For example, not all those lens flares and glowing stage lights were real, just a little added movie magic.

The movie fires on all cylinders, laugh out loud jokes, and is a fun ride through cutthroat college competitiveness.  The music lover in you will jump up and cheer at some of the numbers.  Catch Pitch Perfect on Bluray and DVD starting Dec 18th.

Photos Property of Universal Pictures