SU1448331A1 - Apparatus for measuring mean square granularity of photographic materials - Google Patents

Abstract

The invention relates to systems for measuring structural and metric characteristics and is intended to measure the mean square granularity of photographic materials. In order to increase the accuracy of the measurement of the mean square granularity of photographic materials, the switch 5, the comparator 8 and the sample device 7 — signal storage connected between the signal and other blocks — are additionally introduced into the device so that the signal coming from the electrolytic filter 4 passes to the extraction unit 6 RMS cleared-from interference. 1 hp f-ly, 1 ill. with (

Description

The invention relates to systems for measuring the structural characteristics of photographic materials and is intended to measure the mean square granularity of photographic materials.

The purpose of the invention is to increase the reliability of measurements of the rms granularity of photographic materials.

The drawing shows a diagram of the device.

The device contains an o-mechanical optic unit 1 and a photodetector 2 connected in series, a log amplifier 3, a band-pass filter 4, a switch 5 and a unit for the root-mean-square value of signal 6, the output of which is the output of the device. At the same time, in the feedback circuit between the output of the device and the second input of the switch, a sampling block for signal storage 7c is installed. In addition, the device contains a comparator 8, the first and second inputs of which are connected to the output of block 4 and the output of the device, respectively its output is connected to the control inputs of blocks 5 and 7.

The device operates as follows. ,

In block 1, an enlarged image of a sample of a photographic material is scanned with a measuring aperture. In this case, at the output of the photodetector 2, the electrical signal is proportional to the transmittance, and at the output of the logarithmic amplifier 3, the optical density of the scanned area. The band-pass filter eliminates low-frequency interference caused by uneven sample illumination and instability of the light flux in 1 5 and high-frequency noise of blocks 2 and 3. Depending on the signal at the control input, switch 5 passes a signal to the block 6 exit fshgtra (f (t;)), or from block 7 - (b).

Comparator 8 generates a signal Z signC / (t) / - Zb). Fed to the control inputs of blocks 5 and 7. At Z -1, the output of block 5 passes the signal from filter 4, and block 7 remembers the signal sent to it input output signal wq. At z +1, fixed by block 7. The signal through the switch enters the input of block 6. Since the granularity signal at the output of block 3 is a normal random process (t), with dispersion Q, the probability of it exceeding the B3 threshold is small (P 0.0028). Therefore, in the absence of interference, the signal T (t) is fed directly to the rms extraction unit.

When the setpoint signal (in this case, Zbd) is increased, the output of the block 6 is fed through the feedback circuit, i.e. the signal at the input of the RMS allocation unit, F (t) is equal to

Fa) p:

I l

i.t},

Where

- relative duration

interference. r Easy to identify 6V,

, 2 fg 2

6 F (t) dt J, .dt +

+ / fb) dt -6;% (l-V) 6 /

Rtkuda 6 g € e. Therefore, the proposed device ensures that the measurement results of non-quadratic granularity are independent of interference.

Claims (1)

1 .. A device for measuring the mean-quadratic granularity of photographic materials, comprising an optical-mechanical unit and a photo-receiver connected in series, a logarithmic amplifier, an electric filter and a unit of the root-mean-square value of the signal, is characterized in that, in order to increase the reliability of the measurement of the mean square granule photomatics. It also contains a switch, a comparator and a signal storage unit, the output of the electric filter connected to one of the inputs of the switch, the output of which is connected to the input of the RMS value selection unit, the output of which is the output of the device A signal is installed in the feedback circuit between the output of the device and the second input of the switch, with the first and second inputs of the comparator being connected to the output of an electrical 1D48331 filter and output device2. The device according to p, I, TL and, respectively, and its output is connected by the fact that the switch filter is electrically controlled by the control inputs in half the floor of the signal-storage filter.