| For the first time ever, GAMMA
& DENSITY introduces a simple system for accurate translation of IRE
units into printing light equivalents without any additional equipment,
software, etc. . The principle is a visual comparance between 45 IRE
on GAMMA=1c chart as exposed on the set, and the same 45 IRE field on
the GAMMA-1t telecine negative control strip. When using the GAMMA=1c
Chart and the T.C.S., 1 printing light is equal to 2 IRE units.
Example: After setting the 45 IRE field of the GAMMA=1t negative control strip on the 45 IRE mark on the wave form monitor, the telecine colorist will put your camera negative on the telecine machine and roll to the GAMMA=1c chart. If the 45 IRE field from your negative falls on the 65 IRE mark, it is fair to say that your negative would have to be printed about 10 printing lights higher than the LAD printing numbers from any lab. [2 IRE =1 printing light.] The cinematographer immediately knows the negative is overexposed and can take the steps necessary to correct the problem (assuming it is unintentional).
|
The other system of evaluation
is rather cumbersome and not easy to apply.
It takes a lot of time to adjust, needs special software, and creates wasted energy for looking up tables, etc. The results are printing lights which are different not only from lab to lab, but are abstract numbers from printer to printer. Even in this case, look up tables are needed for virtually every lab. This other system requires the ACCOM still store box as part of telecine machine.
Also it is necessary to have an Aaton Keylink digital keyer for the Rank Cintel or Phillips telecines. This ability can be activated only by the "GreyFinder" software. Then, it needs Telecine calibration. The Keylink calibration screen shows three RGB bargraphs that are on three bands: gray, black and white. With the appropriate TEC-V or TEC-P film being placed into the telecine gate, the colorist adjusts the position of the three voltmeter samplers to hit the gray, black and white patches of the TEC film image. With thanks to the Keylink screen, nine bargraphs permanently monitor the nine interacting RGB levels.
Each time the colorist wants to analyze a grey card, he activates the GreyFinder. It first calls the color controller to bypass its secondary color settings and, as the Keylink Keycode reader recognizes the type of film being transferred, it selects its primary color TEC-V or TEC-P setting. With the Telecine on stop, the colorist moves a pointer to hit the card. Wherever and however small it appears on the screen, the pointer then expands its sampling area to the isochrome densities, and the sampled area is hilighted by white lines. By filtering out noise and card defects, this auto-expansion improves measurement accuracy. Assumingly, this method allows the DP to place the grey card in the most relevant part (sic!?) of the picture. The grey card RGB densities are then converted into transfer points (timing values) through rawstock specific look-up tables automatically loaded by the Keylink Keycode reader.
|
