JPH01176559A - Text printing quality control device - Google Patents

Abstract

PURPOSE:To correct influences of the uneven density resulting from the uneven width, gain or loss, of dots on the same printing paper, by determining the character density of a specified character, adding a density correcting amount to the maximum density of said specified character. CONSTITUTION:A character printed object 1 which is an object to be controlled is set on a transparent platform 3 above a flat-bed image scanner 2. When a light shielding window 4 is closed and a switch 5 is turned ON, the data begins to be read by the image scanner 2 and transferred to a processor 6 via a cable 7. The data is taken into an input means 11 as image signals showing the light and shade of a specified character in the printed object 1, which is digitized through a LOG circuit 12 and a digitizing means 13, corrected with the optical distortions thereof or the like by an image processing means 14 and finally stored by a storage means 15. At this time, the correcting value of the density corresponding to the dot width of the specified character is determined from a correction table. The determined correcting density is added to the maximum density of the character part, so that the character density of the printed object is determined.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is for managing the printing quality of printed text such as dictionaries and textbooks, which mainly contain text printed by printing machines such as offset printing machines and letterpress printing machines. This invention relates to a character printing quality control device.

<Prior art> In general, in text printed matter mainly consisting of characters printed by printing machines such as offset printing machines and letterpress printing machines, especially in encyclopedias, dictionaries, textbooks, etc., uniform printing is performed on all pages of the text printed matter. Maintaining constant density and thickness of characters is strongly required for character printing quality.

In order to meet such demands, the present inventors filed a patent application filed in 1983.
476233 character printing quality control device was proposed. This is done by dividing the printed surface reflection density (light intensity) into very fine pixels using an input device for a specific character part of the printed text to be managed, and then inputting the printed text from the pixel pinch and the number of pixels. The density value of the specific character was determined by determining the width of the drawing line, and the density value taken from the pixel within the character line segment and not over the edge of the character drawing line.

<Problems to be Solved by the Invention> In this way, the stroke width and density of characters have been determined as separate data.

However, in general, the causes of uneven density of characters on printed paper include the effects during printing and the effects of the stroke width of the characters, and the narrower the stroke width, the lower the density. The first reason for this is that ink and water are printed in an emulsified state, and the water content tends to increase as the print width becomes narrower.

Another reason is that the thinner the character lines are, the more difficult it is for ink to transfer to the blanket cylinder. For this reason, the narrower the printed character's line width, the lower the density.

If the density is affected by the print width, it becomes difficult to determine the correct character density for printed matter.

Therefore, by converting the density measured in the thin character printing line area to the density value of the sufficiently thick character printing line area, it can be said to be a common density that is independent of the thickness of the character printing line, and it can be used to compare the density of printed text. An object of the present invention is to provide a character printing quality control device that can perform the following operations.

Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention provides an apparatus for managing the print quality of text-based printed matter such as dictionaries and textbooks, which mainly uses text. An input means for scanning a specific character part in a printed matter, dividing it into a plurality of pixels, and capturing the gradation signal for each pixel as a gradation signal for each pixel, and a gradation signal for each pixel captured by the input means. A storage means for storing, a line width calculation means for calculating a line width of a character line by performing predetermined calculations and processing based on the gradation signal stored in the storage means, and a line width calculation means corresponding to the pixel width. and a storage means in which a density correction table for determining the density correction amount is stored in advance, and the character density of the specific character is determined by adding the density correction amount to the maximum density of the specific character. The present invention provides a character printing quality control device.

<Operation> The present invention divides the printed surface reflection density -3~ (light M) into a plurality of very fine pixels and inputs the printed surface reflection density -3 to (light M) using an input device for a specific character part of printed characters to be managed.
The line width of the character is determined from the pixel pitch and the number of pixels, the density correction amount corresponding to the line width is determined from a density correction table stored in advance, and the density correction amount is added to the normal density value. In this way, the influence of density unevenness due to the narrowness of the image line width on the same printing paper surface is corrected, and the density value on the printing paper surface is determined.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external view showing basically an example of the hardware configuration of a character printing quality control apparatus according to the present invention, and FIG. 2 is a functional block diagram of the same character printing quality control apparatus.

First of all, in Fig. 1, 1 is a printed text such as an encyclopedia, dictionary, textbook, etc. that is to be managed, 2 is a flatbed image scanner that is an input means, 3 is a transparent mount above the image scanner 2, and 4 is a light shield. Door 5 is a switch. Further, 6 is a processor that inputs data from the image scanner 2 via a cape-4=Lua, and a monitor 8, a disk device 9, and a mouse device 1o are connected to this processor 6 as shown in the figure. are doing.

Here, the printed text 1 may be printed using a printing press using an offset printing method or may be printed using a printing press using a letterpress printing method. Further, the text is not limited to the same printing machine, and may be printed by a plurality of printing machines. On the other hand, the image scanner 2, which is the input means, has three floors of 8 bits or more and a resolution of 10 bits per 1 mm.
It is preferable to read in about 30 lines. Regarding resolution, the resolution of the human eye is about 10 μm, so if the resolution is too low, quality control becomes meaningless, and if the input is too detailed, the amount of data to be handled increases, and subsequent calculations This is because not only the time required for processing becomes extremely long, but also the capacity of memory and disk for storing the data becomes considerably large. Therefore, in this embodiment, an image scanner using a COD line sensor having a resolution of 16 trees per 1 mm will be described. Note that the input means is not limited to a flatbed image scanner, but can also be a CCD.
It is also possible to use a type camera, a video signal output type camera, a drum type scanner, or a flying spot type scanner. Furthermore, the configuration of the system is not limited to that shown in FIG. 1, and other configurations may be used as long as they have equivalent functionality and efficiency.

Next, in FIG. 2, reference numeral 11 scans a specific character part in the character print l to be managed, divides it into multiple pixels, and generates an optical grayscale pixel signal that is a grayscale signal for each pixel. Input means for converting the received electrical signals and outputting them (
CCD line sensor), 12 is an LO for converting the output signal from this input means 11 into a density value.
G circuit 13 is a numerical means for converting the analog signal which is the output signal from this LOG circuit 12 into a digital signal;
14 is an image processing means for correcting the output signal from the digitization means 13, and 15 is a storage means consisting of a memory for storing the output signal from the image processing means 14.

Further, it is an auxiliary storage means that stores in advance a correction table of character print line widths and density correction values shown in FIG. Reference numeral 51 denotes processing means for performing predetermined arithmetic processing based on the gray scale image signal stored in the storage means 15 to determine the print density of the character printed matter 1. Furthermore, 54 is an output means consisting of a monitor for outputting and displaying the evaluation results by the processing means 51.

Here, the LOG circuit 12 inputs the grayscale image signal as a gradation signal by the CCD line sensor, and since the portion with high print density is an important factor in character quality, the LOG circuit 12 It is used to digitize the gradations of high density areas with high precision and high resolution. However, using a linear amplifier, the A/D conversion bit
The same effect can be obtained by increasing the number of amplifiers or using other nonlinear amplifiers.

Furthermore, the image processing means 14 recognizes that the signal digitized by the digitization means 13 may include information errors due to optical distortion of the CCD line sensor and variations in photoelectric conversion characteristics. A calibration curve or the like is created in advance and the data is stored in the storage means 15, and the data of this calibration curve is called up as appropriate and used for the purpose of correcting signal values. In this case, the calibration method is as follows:
When a flat head image scanner is used in 1, linear (one-dimensional) correction is sufficient, but when a TV left camera is used, planar (two-dimensional) correction is performed due to lighting conditions.

Next, the operation of the character printing quality control device configured as above will be described.

First, an operator sets the printed text 1 to be measured on the transparent pedestal 3 above the flat head image scanner 2 so that the inspection surface of the printed text 1 is in contact with the pedestal 3. Next, when the worker closes the light shielding door 4 for shielding external light and turns on the switch 5, data from the image scanner 2 starts to be transferred to the processor 6 via the cable 7. This data is input by the input means 11 as a grayscale image signal of a specific character in the character print 1, is digitized through the LOG circuit 12 and the digitization means 13, and is then optically processed by the image processing means 14. The image is stored in the storage means 15 after being subjected to various distortions and corrections.

Next, in FIG. 3, if the density A-F is shown from the captured image data for each pixel, the density of the white part of the paper is A, the density of the character part is B, and the intermediate density value of the pixel in the edge part is C2.
When the distance (resolution) of one pixel is P, the edge distance X of the character at the pixel is determined by the following equation.

C=A (P-X)+BX/P A corrected density value corresponding to the image line width is determined from the correction table shown in FIG. Then, the character density of the character print is determined by adding the determined corrected density to the maximum density of the character portion.

<Effects> As described above, according to the present invention, the density value, which normally depends on the thickness of the character line, can be made into a common density, and the density of character lines of any thickness can be compared equally. It becomes like this. Therefore, it becomes possible to correctly evaluate density unevenness in printing.

[Brief explanation of the drawing]

FIG. 1 is a heart configuration diagram showing an embodiment of the character printing quality control device according to the present invention, FIG. 2 is a functional block diagram showing an embodiment of the character printing quality control device according to the present invention, and FIG. 3 is a character printed matter FIG. 4, which is a diagram for explaining the relationship between the density cross-sectional sections at one location of one character, is a correction table showing the relationship between the character stroke width and the corrected density. Patent application: Toppan Printing Co., Ltd. Representative Kazuo Suzuki

Claims (1)

[Claims] In a device that manages the print quality of printed text such as dictionaries and textbooks that mainly contain text, a specific character part of the printed text to be managed is scanned, divided into multiple pixels, and the gradation of each pixel is calculated. An input means for capturing the signal as a signal, a storage means for storing the tone signal for each pixel captured by the input means, and a predetermined calculation/processing based on the tone signal stored in the memory means. and a storage means that stores in advance a density correction table for determining a density correction amount corresponding to the drawing width. A character printing quality control device that determines the character density of a specific character by adding the density correction amount to the highest density of the specific character.