Luttiewhat is film print emulation? the print stage, explained
film print emulation imitates printing the negative for projection. what it does to an image, why colourists use it, and how to add it without wrecking the grade.
film print emulation (pfe) imitates the last step of a photochemical film workflow: printing the camera negative onto print film so it can be projected. most of what people call "the film look" happens at that step, which is why colourists add a print stage even to footage shot on a digital camera.
the negative was never the picture
in a film workflow, nobody watched the camera negative. it's orange, inverted and low in contrast. its job was to record as much of the scene as possible. the picture the audience saw was a print: the negative, exposed onto a positive print stock and developed. for decades that stock was usually kodak's 2383.
so the finished image was two films multiplied together. the negative captured a wide range of light gently. the print took that record and turned it into something with punch.
what the print does to an image
- contrast. a camera negative has a gamma of roughly 0.6; a print stock's is several times higher. most of the image's contrast comes from the print, not the negative.
- dense blacks. the print's shoulder holds shadows down into a rich, deep black instead of a milky grey.
- colour crossover. the print's three dye layers don't behave identically, so shadows drift cool and highlights warm. that's a large part of the "cinematic" palette, and it happens without anyone dialling it in.
- highlight roll-off. bright areas compress smoothly towards the print's base instead of clipping at a hard edge.
how colourists use it
a pfe is a transform, not a creative lut, and it expects a particular input. the classic setup in davinci resolve is to convert the footage into cineon film log, then apply a print emulation lut such as the kodak 2383 luts that ship in resolve's film looks folder. those luts assume cineon input. put rec.709 video straight into one and the result is crushed and too contrasty, which is the most common way people decide pfe "doesn't work".
the other rules follow from the fact that the print adds contrast:
- do the creative grade before the print. you grade "the negative" and let the print shape it, the way a lab would.
- expose for the print. a print look on a normally exposed image often wants a little more exposure going in, so skin doesn't sink into the print's density.
- don't stack prints. a pfe on top of a lut that already includes one doubles the contrast.
trying it without the pipeline
luttie's film engine models both stages directly. you pick a negative and a print, and set exposure and printer lights the way a lab would. it reads ordinary photos and phone video as well as camera log (s-log3, c-log3, n-log, apple log and dji d-log), so there's no cineon conversion to set up first. grading with it in the browser is free; saving the result as a .cube lut for resolve, premiere or final cut is part of luttie pro.
luttie's cinema print is shaped after kodak's published 2383 sensitometry. it hasn't been measured against real film, and luttie isn't affiliated with kodak.