SCREENING PROCESS SIMULATION APPARATUS

• US 3,629,493 A
• Filed: 11/06/1969
• Issued: 12/21/1971
• Est. Priority Date: 11/06/1969
• Status: Expired due to Term

• Current Assignee: Rudolph A. Morgenfruh
• Original Assignee: Rudolph A. Morgenfruh
• Inventors: Morgenfruh, Rudolph A.
• Application Number:
  US04/874,549
• Time in Patent Office: 775 Days
• US Class Current: 358/3.07
• CPC Class Codes: H04N 1/6011 with simulation on a subsidiary picture reproducer H04N1/622 takes precedence; matching two or more picture reproducers H04N1/6052

Abstract

Disclosed is apparatus useful for electronically simulating the variable graphic arts process step of photographically screening a continuous tone image to develop a corresponding halftone image. The apparatus is readily adjustable for operation over all or any selected portion of a basic nonlinear signal translation characteristic, and thus is capable of simulating any of a plurality of different screening processes and variations in the adjustable parameters of any single screening process. Other embodiments are covered.

Claims

1. Apparatus for independently and electronically simulating the graphic arts process step of screening a continuous tone image to develop a corresponding halftone image, comprising:

signal translation means, consisting of a single signal translating channel having a predetermined nonlinear input signal amplitude to output signal amplitude translation characteristic different portions of which are proportiOnal to the continuous-tone to halftone conversion that occurs in corresponding different screening processes to be simulated, for translating a supplied signal over a portion of said characteristic determined by the range of amplitude variations of the supplied signal;

adjustable input signal modifying means, responsive to an input signal having amplitude variations within a first range of values and representative of a continuous tone image, for adjustably modifying said input signal to develop a modified signal having amplitude variations proportional to those of said input signal but extending over a selected second range of values corresponding to the portion of said nonlinear signal translation characteristic that represents a selected one of said different screening processes and for supplying said modified signal to the signal translating channel of said signal translation means; and

adjustable translated signal modifying means, coupled to the output of the signal translating channel of said signal translation means, for modifying said translated signal to develop a resultant signal having amplitude variations proportional to those of said translated signal and extending over a selected third range of values and representative of a desired halftone image which can be developed from said continuous tone image by means of said selected screening process.

2. Apparatus constructed in accordance with claim 1 wherein the signal translating channel of said signal translation means has an input-to-output signal translation characteristic that is fixed and substantially S-shaped in form.

3. Apparatus in accordance with claim 2 wherein said means for modifying the input signal comprises means for modifying the peak-to-peak amplitude of said input signal thereby to develop said modified signal.

4. Apparatus constructed in accordance with claim 2 wherein said means for modifying the input signal comprises means for modifying both the peak-to-peak amplitude and the DC component of said input signal thereby to develop said modified signal.

5. Apparatus constructed in accordance with claim 2 wherein said means for modifying the translated signal comprises means for modifying the peak-to-peak amplitude of said translated signal to develop said output signal.

6. Apparatus for independently and electronically simulating the graphic arts process step of screening a continuous tone image to develop a corresponding halftone image, comprising:

signal translation means, consisting of a single signal translating channel having a predetermined nonlinear input signal amplitude-to-output signal amplitude translation characteristic different portions of which are proportional to the continuous-tone to halftone conversion that occurs in corresponding different screening processes to be simulated, for translating a supplied signal over a portion of said characteristic determined by the range of amplitude variations of the supplied signal;

first signal amplitude modifying means, responsive to an input signal having amplitude variations within a first range of values and representative of a continuous tone image, for adjustably modifying the amplitude of said input signal to develop a first modified signal having amplitude variations proportional to those of said input signal but extending over a selected different range of values;

means for modifying the direct current component of said first modified signal to develop a second modified signal having amplitude variations proportional to those of said first modified signal but extending over a selected range of values corresponding to the portion of said nonlinear signal translation characteristic that represents a selected one of said different screening processes and for supplying said second modified signal to the signal translating channel of said signal translation means; and

second signal amplitude modifying means, coupled to the output of the signal translating channel of said signal translatiOn means, for adjustably modifying the amplitude of said translated signal to develop an output signal having amplitude variations proportional to those of said translated signal and extending over a selected third range of values and representative of the desired halftone image which can be developed from said continuous tone image by means of said selected screening process.

7. Apparatus constructed in accordance with claim 6 wherein the signal translating channel of said signal translation means has an input-to-output signal translation characteristic that is fixed and substantially S-shaped in form.

8. Apparatus constructed in accordance with claim 7 wherein said first and second signal amplitude modifying means each comprises an adjustable gain amplifier, for modifying the peak-to-peak amplitude of said input and translated signals, respectively, thereby to develop said first modified signal and said output signal, respectively.

9. Apparatus constructed in accordance with claim 7 wherein said means for modifying the DC component of said first modified signal comprises an adjustable DC clamp circuit for clamping a reference portion of the first modified signal to a selected DC reference level, thereby developing said second modified signal.

10. In an electronic system for simulating graphic arts processes, apparatus for independently simulating the process step of screening a continuous tone image to develop a corresponding halftone image, comprising:

a single nonlinear amplifier, consisting of a single signal translating channel having a predetermined nonlinear input signal amplitude to output signal amplitude translation characteristic that is fixed and substantially S-shaped in form and different portions of which are proportional to the continuous-tone to halftone conversion that occurs in corresponding different screening processes to be simulated, for translating a supplied video signal over a portion of said characteristic determined by the range of amplitude variations of the supplied signal;

a first adjustable gain amplifier, responsive to an input video signal having amplitude variations within a first range of values and representative of a continuous tone image, for adjustably modifying the peak-to-peak amplitude of said input video signal to develop a first modified video signal having amplitude variations proportional to those of said input video signal but extending over a selected different range of values;

a direct current level set circuit for clamping a reference portion of said first modified video signal to an adjustable direct current reference level, thereby to develop a second modified video signal having amplitude variations proportional to those of said first modified signal but extending over a selected second range of values corresponding to the portion of said nonlinear signal translation characteristic that represents a selected one of said different screening processes and for supplying said second modified video signal to the input of said nonlinear amplifier; and

a second adjustable gain amplifier, coupled to the output of said nonlinear amplifier, for adjustably modifying the peak-to-peak amplitude of said translated video signal to develop a resultant video signal having amplitude variations proportional to those of said translated video signal and extending over a selected third range of values and representative of the desired halftone image which can be developed from said continuous tone image by means of said selected screening process.