Jump to content
Mi Ki

Color timing - how was it done?

Recommended Posts

I am wondering how did they color grade movies photo-chemicaly in laboratory. I cant imagine how it was done without a computer.

Share this post


Link to post
Share on other sites

To color grade when printing negative, most laboratories were equipped with an analog video "interpreter". It illuminated and read the negative, and produced a positive display approximating the characteristics of a color print film, and it allowed the operator to adjust three channels R, G, B corresponding to the printing light controls and see their effects. Since color adjustment in printing consisted of no more than those three controls, this much of a "computer" sufficed.

Share this post


Link to post
Share on other sites

Just think of printing as shining a light through the negative so that the image gets exposed onto the print stock. Since the print stock is also a "negative" stock in the sense that it reverses the light values, you are basically taking a negative picture of a negative image and thus creating a positive image. So shine more light and the image on the print gets darker, shine less light and it becomes lighter. This is the way it works in printing b&w negatives to print stock. So to be able to correct the color, instead of a single white light, you shine red, green, and blue light through the negative onto the positive and by changing the individual levels of red, green, or blue, you can adjust the overall color bias in one direction or another while also making the image overall brighter or darker.

 

That's basically it.

Share this post


Link to post
Share on other sites

Tangential: were/are IPs used, because lots of INs were/are needed or because a satisfactory positive intermediate stock was never produced? (Or because a more complex and material-intensive printing process was/is more profitable, for film manufacturers and labs?)

Share this post


Link to post
Share on other sites

An Intermediate Positive is the step between the Original Color Negative and the Duplicate Negative. Color Intermediate Stock is used. Its qualities are a very long straight middle portion of the HD curve, very fine grain and high sharpness and a gamma close to 1.0.

 

In the color process, the same stock is used for both IP and DN. From one IP many DNs can be made and from each DN many thousands of prints could be made. During the 1980s there was also a Color Reversal Intermediate stock which was processed in a modified ME4/ECO3 type of process but with much higher agitation. Using this stock, you could make a copy negative in one step instead of two.

 

Just today I received an old 35mm B&W negative where the original timing sheets were still in the cans. It is a simple list of numbers with a value of 1 to 4 next to it, the nitrate negatives (Pathé Vincennes with a few feet of Kodak) were notched. So the printer operator would follow the chart and preposition the printer to the next aperture (1 to 4), the notch in the film would trigger the exact change to the new setting;

 

Later this system was improved with a 35mm black paper tape in which holes of various sizes were puched according to the amount of light needed on the shot. After the introduction of color, initially gelatin filters were glued to the punched 35mm paper tape. All these systems were substractive color. In the 1960s Bell and Howell perfected the additive lighthouse where three light valves modulate white light that is split into the three primary colors RGB by dichroic filters and after modulation recombined into colored light by mirrors. A punched paper tape was used to control the three light valves with values from 0 to 50. One step is about 1/6 of a stop or 0.025D. Initially notches or metal foil was used on the film to trigger light changes but later Frame Count Cueing was used making changes much easier.

 

I will write more about the way the film grader works later if anyone is interested.

Share this post


Link to post
Share on other sites

One step is about 1/12 of a stop or 0.025D. This might seem unnecessarily fine, but the color positive film had a gamma of about 4, so the 1/12 of a stop made a luminance change of about 1/3 stop, quite noticeable.

 

What the new generation of Mi Ki needs to hear from the old generation is how pathetically weak a color correction was possible by control of just the R, G, B printing lights. Contrast adjustment was not possible, neither for individual layers nor for them together. Saturation adjustment, such as every digital beginner enjoys, was unthinkable. Etc. This does not mean that the color timing was trivial. To the contrary, it required extreme skill to harmonize images by such weak means. We sometimes made radical color changes in place of the small simple ones we couldn't make.

Edited by Dennis Couzin

Share this post


Link to post
Share on other sites

Here's a good article about how a Hazeltine color timer works: http://www.theasc.com/ac_magazine/September2006/DigiPrinterLights/page1.php

I took a tour of Fotokem probably 10 years ago, and this was the color timer they were still using for photochemical prints. I'd imagine that hasn't changed, except far fewer people use it now.

 

And here's the sales brochure from 1969. Pretty neat stuff: https://archive.org/stream/bitsavers_hazeltineHalyzerBrochureSep69_2848682/Hazeltine_Color_Film_Analyzer_Brochure_Sep69#page/n0/mode/2up

Edited by Josh Gladstone

Share this post


Link to post
Share on other sites

If printing from color negative to positive, you need 6 printer points to compensate 1 stop on the negative, if printing to reversal or intermediate, it would be 12 points as Dennis pointed out.

Share this post


Link to post
Share on other sites

Just think of printing as shining a light through the negative so that the image gets exposed onto the print stock. Since the print stock is also a "negative" stock in the sense that it reverses the light values, you are basically taking a negative picture of a negative image and thus creating a positive image. So shine more light and the image on the print gets darker, shine less light and it becomes lighter. This is the way it works in printing b&w negatives to print stock. So to be able to correct the color, instead of a single white light, you shine red, green, and blue light through the negative onto the positive and by changing the individual levels of red, green, or blue, you can adjust the overall color bias in one direction or another while also making the image overall brighter or darker.

 

That's basically it.

David, you need to create some online training materials...I was starting to formulate in my mind how to explain the process and then read your post and was amazed at how clear and concise it was.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



  • Ritter Battery



    Rig Wheels Passport



    Serious Gear



    New Pro Video - New and Used Equipment



    Glidecam



    CineLab



    Wooden Camera



    Media Blackout - Custom Cables and AKS



    Tai Audio



    Paralinx LLC



    Metropolis Post



    Gamma Ray Digital Inc



    Broadcast Solutions Inc



    Abel Cine



    Visual Products


×
×
  • Create New...