JPS581150A - Evaluating method for original for printing - Google Patents

Abstract

PURPOSE:To convert information on the brightness of a color original into information on density by fetching the brightness information on a density scale arranged in parallel to the color original, finding the correspondence relation between the brightness and density, and then generating and storing a brightness-density conversion table. CONSTITUTION:Light transmitted through an original 1 which is placed on a light table and lighted from below is supplied through a filter 2 to a TV camera 3 to take a photograph, and the output of the TV camera 3 is supplied to an A/D converter 4, whose output is supplied to a TV monitor 6 through a video controller 5 and also supplied to a computer system through an interface 7. Then, brightness information on a density scale arranged in parallel to the original is fetched to find the correspondence relation between the density scale and each density band. To improve the precision of the data, the same data is fetched several times and the mean value is stored in a DMA transfer buffer as the brightness information on a gray scale. The correspondence relation between the density of each band of the gray scale and brightness information (A/D- converted value) is obtained and contained in a conversion table.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing original evaluation method, and more particularly to a method of converting luminance information extracted from a printing original into density information.

When color-separating a color original for printing, deciding on the highlight reference point in determining separation conditions is an important issue that greatly affects the quality of the original.

Conventionally, the determination of color separation conditions has relied on the subjective evaluation of color originals by the operator. In this case, as an auxiliary means for the operator's evaluation, it is not necessary to use the point view #IN result of the color original by a densitometer or scanner beam, or to use the aflll determination result by camera division. There is. However, the color document evaluation Kd fluctuates due to the skill fK of the operator.

Therefore, a color document evaluation AT as shown in Japanese Patent No. 55-92414 has been developed. This is as follows. First, apply an ND filter to the color original placed on the light table, shoot it with a TV camera, display it on the monitor, perform arbitrary 1112, □ slice it with a bell, convert it into a binary image, and +! Select a candidate highlight set point for the color separation conditions based on the area and position of the white part of the color document by changing the fv level.0 Next, set the TV camera to red.

A color original is photographed using each of the green and blue filters, and the slice level for each filter is determined so that it is equal to the white area of the candidate highlight set point. Determine. The 1llf distribution and density accumulation curve for the entire surface of the color document using one 7tND filter are determined. These results can be used to improve operator skill (regardless of the operator's skill level).

This means that the quality of the original plate can be made uniform and good.

Here, the conversion from brightness information, which is the basis for determining the highlight set point, to darkness information is accurate and accurate!
The present invention was made with this point in mind, and the present invention was made with this in mind. By inputting the information and determining the correspondence between luminance and 100%, a luminance [-11if conversion table is created and stored on t, and this conversion table is used to convert the luminance (emotion) of a color manuscript into density. It is designed to be converted into information.

Hereinafter, with reference to the accompanying drawings, one aspect of the present invention will be described. ! An example will be explained.

FIG. 1 shows a predetermined configuration according to the present invention, which is a 1rj original, consisting of a so-called printing original and a gray scale having a predetermined density band. This original 1 [is placed on a light table (not shown) and illuminated from below. Light transmitted through original l to filter 2
It consists of a filter that reduces the amount of transmitted light through the TV camera regardless of the color of the TV camera. These filters σ reduce the amount of light reaching the TV right camera from the printing document 1.

Even though the dynamic range of the TV right camera is narrow, the brightness If information in a wide density range is output. Dark [1
, 4 to 2.1, etc.

The output of the TV right camera is fed to a converter 4 and further fed to a TV monitor 6 via a video controller 5, while being fed to a computer system via an interface q. Combi child--System ArjCP
U8. RAM9. DMA:yy) Consists of o-910, display fold (111-) and external memory 12.

Next, referring to FIGS. 2 to 5, the operation of converting brightness/subordination information to Sakaki-ryo information in the present invention will be explained.

As shown in Figure 2, a printing original and a density scale are set on the light table. In this state, first set the filter for #IfO,O to 0,7 foot measurement, apply the brightness/darkness information of the *W school, and find the correspondence between each a degree band of the density school and the brightness counterfeit information. At this time, in order to improve the data, the same data is captured multiple times and the average value is used as clay scale brightness information.
Store in A transfer buffer.

The density and brightness of each band on the V-scale are ff1lF (A
/b conversion value), make this correspondence into a conversion table.
, 05 thick electric increments) are 2 9 ways on the left side of Table 1 below, the address assignment of Memo IJ 12 is performed to create a conversion table as shown in the right column of Table 1 and Table 2 below.

Table 1 Note: An A/b value of 21 or less indicates a concentration greater than 0.7, so it is treated as invalid data in step 1.

Table 2 is related to dlljo, 0 to 0.7, and 1
A conversion table of 6×16 = 256 bytes is created. In this Table 2, the A/l) conversion value is the address from the previous memory address, and its A/i)
The #I stage corresponding to the converted value is equal to the contents of that address.

Figure 3 shows this 1g! The operation for performing the conversion shown in Table 2 and Table 2 is shown as a flowchart.

The original data taken into the #IIIKoMA transfer buffer is converted into the corresponding dark/dark data by the program shown in FIG.

FIG. 4 shows the relationship between the above-mentioned measurement and annotation in the range of fO10 to 0.7 and the subsequent total -1 threat in the range of 0.7 to 1.4. Step lIjo, o~0.7no range [琥 as this l1llf0.7~1
．． Assuming that the range of step 4 is step 211, the filter for measuring this step 2 area is a filter that is darker IfO, 7 minutes thinner than the filter for step l area, so the camera system characteristics -H As shown in Figure 4, dark I
I O, translate to the right in the 7 minute diagram.

Therefore, even if the same φ conversion value as measured by the step 1 filter is obtained, the corresponding density is 0.7 larger.

Therefore, when performing It II f using the step 2 filter, the data on the conversion table of step 1 is slid by 14 steps out of 256 electrical manufacturing steps and used as the conversion table. Here, the characteristic -1!Left from the 20B point @ (hlD conversion value 18H or more) is at step 11 [
The area to the right of the zero point (A/l) less than the displacement value ηH) is the area measured in the step 3 area, so the data at the address of the conversion table corresponding to this area is treated as invalid data φ.・Step 3 area is also processed using the same concept.

In order to explain the advantage of brightness (-density conversion) using the conversion table shown in Table 1 and Table 2, Figure 5 shows a flowchart for performing fIk degree conversion without creating a conversion table. The time it takes to execute the program shown in Figure 5 is significantly longer than the time needed to execute the program when creating the above conversion table, and it is much more expensive to create the conversion table. It is efficiency.t
Using the tt conversion table is convenient for performing bright 1f-allfe conversion using software.

FIG. 6 shows the configuration of this hardware.

This configuration consists of DMA controller 2], latch ρ, 25
6-byte RAM23. and DMA transfer buffer (source @) 24. It consists of a DMA transfer buffer (on the floppy side) 25.

In this configuration, change to RAMZ3! Write table data in advance, ijD when converting between legs-dense t-X
Under the control of the MA controller 4, the data (A/l conversion value) in the DMA transfer buffer (source side) 24 is converted into a corresponding 89-step number and written to the DMA transfer buffer δ on the write side. It will be done. The control II of the address bus is all managed by the DMA controller 21, and data read->conversion->data writing is continuously performed at high speed until a set number of 7 is reached.

DMA #5! In the output cycle, the MEMR signal is output from the DMA controller and the data at the specified address in the DMA transfer buffer (source side) 24 is transmitted onto the data bus. Continued l10W [No.D
The data on the data bus output from the MA controller 21 is input into the 8-pit latch B.

The 8-bit latch 22 is connected to the address of ttRAMZ (9), so when the DMA write cycle begins and T1011 is output from the DMA controller, the contents of latch B (A/ll variable value) are The data on the AT V of RAM T3 specified by 11.MEMW is sent out onto the data bus and stored at the specified address of the DMA transfer buffer δ when the MEMW signal is output.

In this way, the method of creating a conversion table and performing leg-to-double conversion is an effective method that can be easily applied to hardware.

As described above, in the present invention, the brightness of a printing original is determined by taking in the brightness information of the density scale juxtaposed with the printing original and assigning the correspondence between the legs and the density. Since a f-a degree conversion table is created and stored, and the conversion table is used to convert the 42 information of the print document into #I actual information, the leg distance information of the print document can be accurately and quickly converted. This information can be converted into coal-making information, providing useful data for creating printing plates.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the first air filter in which the present invention is implemented; FIG. 2 is a diagram illustrating the acquisition of V-scale Terumo information, which is the first step of the method of the present invention; Figure 4 is a flowchart explaining the conversion of clay scale brightness information into interlayer information;
FIG. 5 shows a luminance-value conversion method using a conversion table according to the present invention and a luminance-value conversion method that does not rely on a conversion table (
70-Chart of the Conversion Method, FIG. 6 is a diagram showing the configuration of a conversion apparatus for implementing the method of the present invention. l... Original for printing, 2... Filter, 3... TV
Camera, 6...TV monitor. Single figure, 2nd figure, 4th figure, 3 figure, 5 figure

Claims (1)

[Claims] In a method for evaluating a printing original in which luminance information is obtained from the printing original, the information is converted into information, and this *tt information is used to evaluate the density distribution state of the printing original and the density accumulation curve.
When taking in the brightness information of a printing original, the brightness information for each density band of a density scale that has predetermined density bands placed side by side with the printing original is taken in and the correspondence relationship between brightness and density is determined. A method for evaluating a printing document, characterized in that a brightness/darkness conversion table is created, and brightness information extracted from the printing document is converted into density information according to the conversion table.