SU794590A1 - Method of colour correcting and determining exposure time at colour printing - Google Patents

Description

depending on the plot content of each frame and, in the case of a negative net density deviating from normal.

The aim of the invention is to obtain,

optimal exposure conditions in

 depending on the plot content of each frame and in the case of a deviation is dense-.

, ti negative from normal. ,

- The goal is to achieve the fact that the correction signals obtained by printing a reference negative result in one value by changing the transmission coefficient for each of the zonal channels, determine the signals characterizing the spectral composition of the luminous flux passing through the negative to be printed, with the subsequent conversion of these signals to inverse values, and the exposure value is set in proportion to one of the obtained values and is given. correction by other channels by changing the spectral composition of the printing light in accordance with the value of the reciprocal of the corresponding channels.

The drawing shows the block diagram of the device that implements the method.

The device consists of the light source 1, the corrective light filters 2, the negative holder 3 for installing the negative 4. The light flux passing through the negative and the corrective light filters is received by a photo-receiver 5 connected at the input of the common amplifier 6, allowing 1} to change the coefficient of the amplifier the entire device. Its output is connected to the input of the switching unit 7, the outputs of which are connected to the inputs are adjustable: zone amplifiers 8, the outputs of which are equipped with indicators 9. In addition, the additional outputs of the switching unit are connected respectively to the input of the comparator 10 and the input of the converter 11 which converts the incoming signal AND to the inverse value 1 / AND, recorded by the indicator. 12 and simultaneously from the output of the converter 11 supplied to the input of the memory unit 13, the output of which is connected to the second input of the comparator device 10. The output signal of the latter leaks by the drive unit 14 of the corrective optical filters 2. The second output of the common amplifier of the channels. connection, is associated with the input of the time relay 15, controlling, the burning time of the light source J.

The method of color correction and exposure determination is as follows. The Negative Holder 5 sets, with

reference, negative 4 and spectr. the composition of the printing light, in which the resulting positive satisfies the conditions and correct light transmission. To do this, a photodetector 5 measuring the spectral components of the light flux is measured, passing through the reference

negative, and the values obtained are recorded by the indicators 9 of the zone amplifiers 8. By adjusting the regulators, the gains of each of the zone amplifiers are designed so as to obtain the same Signal Value at the output of the zone amplifiers, i.e., obtained when printing the reference negative reduced to one value

by changing the transmission coefficient for each channel. Subsequently, the reference negative is removed in its place, the negative is to be printed, and the signals characterizing the spectral composition of the luminous flux passing through the negative light are determined. For this, using the photodetector 5, the luminous flux changes in different zones of the spectrum and the received signals are recorded: indicators 9. Moreover, depending on the absolute value of the registered signals, the average, minimum and maximum signals are printed. For example, the following values are recorded: by

red channel: -92 - average; on the green channel: 100 - maximum; blue channel: 90 - minimum.

Adjusting the gain of the common amplifier channels, set to

the indicator, the channel on which the maximum value was registered, the level corresponding to the value to which the values of all indikatoB were given when printing the reference negative,

for example, 50. Then, the lacasa and the indicators and by will change accordingly. other zonal channels:.

on the red channel: -46 - average; on the Zelets channel: / 50 - maximum;

channel blue: 45 - minimum.

By means of the blocking switches 7, the signals corresponding to the average and minimum values are fed to the input of the converter 11 and converted into inverse

magnitude, according to the red channel: 54; channel blue: 55.

These values are registered by indicator 12 and fed to the input of memory block 18, from the output of which is fed to

one of the inputs of the comparator device 10. At the output of the comparator device, the signal will be until the bale is equal between the signals arriving at its input 1 directly. from the switching unit 7 and the memory unit 13, i.e., until such time as the input of the optical filters necessary for the correction of this frame density and chromaticity is required to drive the correction light filters 14 into the light flux zone.

Claims (3)

1. The patent of Germany No. 1597323, cl. 57 a 8/05, publ. 1970: 2. US patent number 3797933, CL., 305-35, published. 1974. 3.Minolta, Durst Color Transtalor, .1976, (prototype) ...