Pako Corporation

John Pone, Jr

Ronald B Harvey

Jan T Freier

Gerald A Jensen

Patrick J Gilligan

Francis M Laciak

Kenneth B Schrupp

Peter N Seidel

A photographic printer control system of the present invention separates the operation of the printer into first and second working levels. The first (or 'operator') working level includes selecting the printing mode, loading or selecting one of a plurality of setup blocks, initiating printing, and applying color density button corrections. The second (or 'manager') working level includes determination of printer operating parameters for each setup block, selection of automatic corrections to be applied, color balancing, calibration, and totalizing. A control panel supplies input signals which select and control operation on the first and second working levels. A security system is provided to limit access through the control panel to the first working level for all persons except authorized persons such as the lab manager. The regular operator of the printer, therefore, normally cannot initiate operation on the second working level and thereby disrupt operating parameters, color balance, calibration, or totals which have been selected by the lab manager.

Photographic printer control system

The photographic printer of the present invention stores measured gamma values for the photosensitive medium upon which prints are to be made. The gamma values modify exposure times so that the operator button corrections always correspond to a known increment in density. When the photosensitive medium is changed, new gamma values are entered and the printer again modifies exposure times by the appropriate amount so that button correction increments remain constant despite the change in paper gamma.

Photographic printer with automatic density and color corrections for

In the photographic printer of the present invention, color balancing is performed through an interactive procedure with the user. A test print of a reference film negative is made and the densities of the test print are measured and entered into the printer by the user. The printer derives and displays modified exposure times for the reference negative from the density of the reference negative, the desired reference print density values and the measured density values of the test print. The printer then performs a series of density measuring and exposure time calculating cycles during which time, if the modified exposure times differ from desired reference exposure times, the user changes the color content of the print lamp light by moving subtractive filters. The calculated exposure times are displayed so that the operator can monitor the changes in exposure time for each color channel as the subtractive filters are adjusted. The procedure continues until the displayed exposure times equal the desired reference exposure times.

Photographic printer with interactive color balancing

An automatic photographic printer includes a sensor system for providing density signals indicative of measured optical density of a photographic film at a plurality of defined areas of the film. Photographic films containing landscape type scenes, snow/beach type scenes, and other scenes which might be incorrectly identified as subject density failures, are identified. The identified films are excluded from receiving a subject density failure exposure correction, while the remaining films are subjected to an automatic subject density failure exposure correction which is derived from the density signals.

Automatic exposure corrections for photographic printer

An automatic system for classifying photographic negatives containing snow or beach scenes measures the red, green, and blue densities of the negative to be printed. Signals indicative of red, green, and blue exposure times are derived from these measured densities, and the signal indicative of the blue exposure time is compared to the signals indicative of the red and green exposure times. The results of this comparison indicate whether a snow or beach scene is present. To determine the amount of density correction, if any, the densities of the negative at a plurality of points are measured. The extent of the density correction is determined by the number of points whose density is within a predetermined interval of the maximum density measured from any one of the points.

Automatic snow/beach correction for photographic printer

The photographic printer of the present invention automatically derives and stores slope compensation factors which are used in subsequent printing to compensate for exposure. Reference or slope center values are stored for a reference negative and prints of various negatives are made. A print which requires correction is selected from the test prints which have been made, and the desired density corrections for that print are supplied to the printer. The density values of the negative from which the print was made are measured, and slope compensation factors are derived from the slope center values, the desired density corrections, and the measured density values. Exposures in subsequent printings are compensated based upon these derived slope compensation factors.

Photographic printer with automatic slope compensation

An improved exposure time control for a photographic printer includes a digital processor such as a microprocessor. The digital processor receives input signals such as signals from large area transmission density (LATD) sensors, from density or color sensors, and from an operator control panel. Based upon the input signals, the digital processor derives a digital count and a clock control signal for each color channel. The exposure of each color channel is controlled as a function of the time required to change the corresponding digital count from its initial value to a predetermined final value. The changing of the digital count for each channel is caused by the digital processor in response to clock or interrupt signals from variable clocks controlled by the clock control signals. The rates at which the interrupt signals are generated are controlled by the clock control signals.

Exposure time control

An automatic density control device for photographic printers for sensing and correcting for a 'subject failure' in a photographic negative, where the subject area of the negative is out of the optimum density ratio to the background area, which device includes a frusto-pyramidal radiation directing member having its enlarged end proximate to the negative and its small end remote therefrom and being positioned to receive the radiation from a source through the negative and having subject sensing means mounted at the central portion of the enlarged proximate end of said member to sense the radiation passing through the central subject area of the negative and also having background sensing means mounted at the diminished remote end to sense the radiation passing through the marginal portions of the negative and the marginal portions of the enlarged end of said member and including circuitry for comparing the signals produced by said subject sensing means and background sensing means and thus deriving a density signal which is used to control the exposure time during the printing process.

Growing community of inventors

Minneapolis, MN, United States of America

John Pone, Jr