Where should the color code be placed?
In practical applications, the printing operator can place the color mark in any suitable place, such as the upper or lower edge of the paper or sheet format, the margin trimming area at the top, and the gutter section printed along the cylinder. Although this option is not suitable in the end, because it can only provide channel information to the ink supply system of the printing press, it is better to measure some data and observe the limits of these data than nothing.
In the most ideal situation or when maximum control is required and the typesetting position permits, the color mark should be placed across the typesetting page, parallel to the ink supply cylinder, and as close as possible to the center of the printed page, because at the beginning and end of the typesetting page There is a greater possibility of changes at the edges. This placement method can measure across the length of the printed matter, and can provide good printing information for the entire paper.
Take care to avoid placing color patches where they may be folded, cut or punched. These will hinder or destroy the measurement values ​​obtained by printing color scales.
It is recommended that if time and materials allow, it is best to use the same color-coded film to print the job and test version, placed on the top edge, center, bottom edge and along the direction of the cylinder. Include pictures in the test layout, print them so that the pictures match the pre-proofing proofs of the test layout, and then select some printing features while ensuring the stability of the printing press. Measure the color scales of these four locations separately, and compare their dot gain, density, and other measurement data. Through these operations, you can realize the effect of different color mark positions on the measurement data, including whether a color mark placed along the direction of the cylinder can provide more information on the test copy reproduction status.
What should I do if a complete color mark cannot be placed in the layout?
Experts suggest that printing operators should at least place a solid color block of each color and a 75% density color block of the corresponding color somewhere in the layout, or in a specially designed icon or other customer approved element , Including black, even if these eight color patches are to be placed in the gutter. The reason for this suggestion is that the printing quality of the dark areas directly affects the quality of the entire printed product, and the human eye is also more sensitive to the resolution of this part. The measurement of printing contrast is a more technical term. It can be obtained by measuring field objects and 75% chroma blocks, and this data can be used to convey the information of printing quality.
If it is not possible to use a complete color scale in every job, you can choose to use the color scale in as many jobs as possible, or at least the complete color scale in stages, such as once a week or once a month. This will help to find the problem during the actual operation evaluation and analyze the cause of the problem. Remember to take a measurement is better than no measurement. Also note that if someone controls the production process, the quality of the product will be better.
Can the back of the color code be printed again?
If you use standard black backing materials such as BackStopTM during the measurement of the color mark, it does not matter whether the back of the color mark is still printed, because this black backing eliminates the measurement changes caused by the pattern printed on the reverse side of the printed sheet.
If you do not use black backing material, in order to ensure the most accurate measurement and analysis, the printed color code should not print any patterns on the back. Because any paper is not completely opaque, the printing on the reverse side of the paper will be measured by the densitometer, affecting the final measurement value. (Note: The measurement results with a black lining cannot be compared with the measurement results without a black lining, nor can it be compared with an object with a pattern printed on the back.)
The ANSI / ISO standard stipulates that a black backing should be used for measurement. However, since most printing companies print the color code at the same position on both sides of the printed sheet, because this can save space and facilitate the positioning of the layout, most of the black backing has been eliminated Lined up.
Even if other patterns are printed on the back of the color scale, and there is no black backing on hand, printing and measuring the data on the color scale is better than nothing. Just be aware that compared to other operations, this type of measurement is more affected by additional variables and the results will be slightly different. As mentioned earlier, it is better to take a measurement than no measurement.
When measuring proofs or prints, why is a black backing better than a gray or white backing?
ANSI / ISO 5 / 4-1983 (R.1986)-ANSI PH 2.17-1985: Density Measurements Geometric Conditions for Reflection Densitometry (reflection density measurement geometric observation conditions) defines the geometric observation conditions of reflection density measurement . This standard material contains the following introduction:
"This international standard specifies that the surface of the material on the back of the sample to be tested should be spectrally non-selective and diffusely reflective, and that the ISO reflection density value is 1.50 ± 0.20, which is very important. [Note: Spectral non-selective The surface is a gray surface; gray tones with a reflection density value of about 1.50 should show black]. Some reflection density standards usually specify that the backing material should have a lower reflection density. "Standard Annex A further explains:" When determining the reflection density in a well-defined observation condition, it is very important to determine the characteristics of the material used behind the sample. "
According to the document, there are many reasons for the choice of black backing, including:
The black backing reduces the variable factors during the measurement process. Since many samples used in the printing and publishing process are usually not completely opaque, the pattern printed on the reverse side of the paper will affect the measurement results, and sometimes even greatly. Therefore, for operations that are aimed at measurement and process control, this Point is very important. According to a survey by the PSI Association, when measuring substrates with a transmission density equal to or less than 1.00, different backing materials and patterns printed on the reverse side of the material will affect the measurement results.
· From the perspective of spectrum, density and physical requirements, the use of backing materials can greatly reduce the measurement data of low-density surfaces.
· The use of black backing can directly calculate the absorption ratio based on the density reading.
The standard also warns that samples in the printing industry are usually backed by two or more layers of the same backing material before observation. There is no reason why the ISO density value of the sample combined with the density value of the printing image and the printing material cannot be read together, although some precautions should be taken to determine the reading of the image and the printing material together, not the image layer itself Reading.
The change in measurement values ​​due to the absence of standard backing materials continues to intensify as the paper becomes thinner and the projected density value decreases. The initial investigation and research conducted by the PSI Association in this regard showed that for the printing industry paper, the delta density value of the paper under the conditions of black and white backing measured from 0.07 to 0.002, under the same circumstances, the transmission density value It will increase from 0.3 to 1.2. From the data, we can see that the difference between the transmission density of the printing material and the data measured by the same material under different black and white backings has an exponential relationship. The white backing used in this investigation is a non-selectively absorbable material coated with ceramic tiles on white steel, which is non-fluorescent and has a reflection coefficient of 89%. / ISO regulations. In order to actually observe the transmission density value of the paper, the PSI Association investigated several different papers and found that the transmission density value of the thinner paper used for multi-page publications and Bibles is about 0.30; 20 pounds white cloth offset The transmission density of the paper is about 0.60; the transmission density of 80 pounds of coated card material is about 0.90; and the transmission density of 120 pounds of coated card material is about 1.20. These investigations also show that the situation of photographic paper is similar, but with different curves.
Realizing that the black backing minimizes changes in the measurement results, it is recommended to use a standard black backing in the following situations:
· Instrument installation;
· Calibration of the instrument (Note: During the installation of the density meter, the calibration black backing used is very important, because this backing is defined in the ANSI / ISO density standard.);
· Specification of job parameters (for example, printing a job to determine the target point), unless a different backing is specified;
· Industry parameter specification (for example, the printing type of products such as magazine advertisements to determine the target point), unless a different backing is specified;
· Exchange measurement data between different organizations unless a different backing is specified.
For internal users, for example, an operator subjectively estimates an image and compares it with a proof or another model. The black backing will make the printed image look slightly different, which is not applicable at this time. . As suggested in the standard, in these cases the operator is likely to place one or more unprinted substrates under the paper and then evaluate it.
Many members of international organizations plan to develop a standard white backing. The standard of this backing must redefine the following parameters:
· Color · Brightness · Surface diffusion phenomenon · Fluorescence · Density In order to ensure the transmission of the measurement results, each of the above factors should be recorded when using the white backing to ensure that the receiver of the measurement results can understand the operation of these measurement results .
From the two perspectives of measurement standards and user standpoints, the currently used standards have a certain stability, and the convenience of using black backing (existing materials, and common under various conditions, to ensure consistency with the current ANSI standard) And the challenge of defining a white backing shows that the development of a white backing standard will not help to reduce the variation in measurement results, nor will it reduce the user application of standard backing materials.
In general, the industry recommends a standard black backing for color measurement for measurement and process control purposes. This should be a standard method to ensure that these measurement operations are not affected by factors such as printing on the reverse side of the paper or the disproportionate image on the paper. The printing materials should not be stacked together during the measurement. First of all, if a black backing is not used during the density measurement, the user should communicate the information of the backing used, and also be aware that this measurement result is affected by additional changes. The degree of influence of these changing factors can be determined by comparing the measured readings of the same paper material with and without a standard black backing.
In practical applications, the printing operator can place the color mark in any suitable place, such as the upper or lower edge of the paper or sheet format, the margin trimming area at the top, and the gutter section printed along the cylinder. Although this option is not suitable in the end, because it can only provide channel information to the ink supply system of the printing press, it is better to measure some data and observe the limits of these data than nothing.
In the most ideal situation or when maximum control is required and the typesetting position permits, the color mark should be placed across the typesetting page, parallel to the ink supply cylinder, and as close as possible to the center of the printed page, because at the beginning and end of the typesetting page There is a greater possibility of changes at the edges. This placement method can measure across the length of the printed matter, and can provide good printing information for the entire paper.
Take care to avoid placing color patches where they may be folded, cut or punched. These will hinder or destroy the measurement values ​​obtained by printing color scales.
It is recommended that if time and materials allow, it is best to use the same color-coded film to print the job and test version, placed on the top edge, center, bottom edge and along the direction of the cylinder. Include pictures in the test layout, print them so that the pictures match the pre-proofing proofs of the test layout, and then select some printing features while ensuring the stability of the printing press. Measure the color scales of these four locations separately, and compare their dot gain, density, and other measurement data. Through these operations, you can realize the effect of different color mark positions on the measurement data, including whether a color mark placed along the direction of the cylinder can provide more information on the test copy reproduction status.
What should I do if a complete color mark cannot be placed in the layout?
Experts suggest that printing operators should at least place a solid color block of each color and a 75% density color block of the corresponding color somewhere in the layout, or in a specially designed icon or other customer approved element , Including black, even if these eight color patches are to be placed in the gutter. The reason for this suggestion is that the printing quality of the dark areas directly affects the quality of the entire printed product, and the human eye is also more sensitive to the resolution of this part. The measurement of printing contrast is a more technical term. It can be obtained by measuring field objects and 75% chroma blocks, and this data can be used to convey the information of printing quality.
If it is not possible to use a complete color scale in every job, you can choose to use the color scale in as many jobs as possible, or at least the complete color scale in stages, such as once a week or once a month. This will help to find the problem during the actual operation evaluation and analyze the cause of the problem. Remember to take a measurement is better than no measurement. Also note that if someone controls the production process, the quality of the product will be better.
Can the back of the color code be printed again?
If you use standard black backing materials such as BackStopTM during the measurement of the color mark, it does not matter whether the back of the color mark is still printed, because this black backing eliminates the measurement changes caused by the pattern printed on the reverse side of the printed sheet.
If you do not use black backing material, in order to ensure the most accurate measurement and analysis, the printed color code should not print any patterns on the back. Because any paper is not completely opaque, the printing on the reverse side of the paper will be measured by the densitometer, affecting the final measurement value. (Note: The measurement results with a black lining cannot be compared with the measurement results without a black lining, nor can it be compared with an object with a pattern printed on the back.)
The ANSI / ISO standard stipulates that a black backing should be used for measurement. However, since most printing companies print the color code at the same position on both sides of the printed sheet, because this can save space and facilitate the positioning of the layout, most of the black backing has been eliminated Lined up.
Even if other patterns are printed on the back of the color scale, and there is no black backing on hand, printing and measuring the data on the color scale is better than nothing. Just be aware that compared to other operations, this type of measurement is more affected by additional variables and the results will be slightly different. As mentioned earlier, it is better to take a measurement than no measurement.
When measuring proofs or prints, why is a black backing better than a gray or white backing?
ANSI / ISO 5 / 4-1983 (R.1986)-ANSI PH 2.17-1985: Density Measurements Geometric Conditions for Reflection Densitometry (reflection density measurement geometric observation conditions) defines the geometric observation conditions of reflection density measurement . This standard material contains the following introduction:
"This international standard specifies that the surface of the material on the back of the sample to be tested should be spectrally non-selective and diffusely reflective, and that the ISO reflection density value is 1.50 ± 0.20, which is very important. [Note: Spectral non-selective The surface is a gray surface; gray tones with a reflection density value of about 1.50 should show black]. Some reflection density standards usually specify that the backing material should have a lower reflection density. "Standard Annex A further explains:" When determining the reflection density in a well-defined observation condition, it is very important to determine the characteristics of the material used behind the sample. "
According to the document, there are many reasons for the choice of black backing, including:
The black backing reduces the variable factors during the measurement process. Since many samples used in the printing and publishing process are usually not completely opaque, the pattern printed on the reverse side of the paper will affect the measurement results, and sometimes even greatly. Therefore, for operations that are aimed at measurement and process control, this Point is very important. According to a survey by the PSI Association, when measuring substrates with a transmission density equal to or less than 1.00, different backing materials and patterns printed on the reverse side of the material will affect the measurement results.
· From the perspective of spectrum, density and physical requirements, the use of backing materials can greatly reduce the measurement data of low-density surfaces.
· The use of black backing can directly calculate the absorption ratio based on the density reading.
The standard also warns that samples in the printing industry are usually backed by two or more layers of the same backing material before observation. There is no reason why the ISO density value of the sample combined with the density value of the printing image and the printing material cannot be read together, although some precautions should be taken to determine the reading of the image and the printing material together, not the image layer itself Reading.
The change in measurement values ​​due to the absence of standard backing materials continues to intensify as the paper becomes thinner and the projected density value decreases. The initial investigation and research conducted by the PSI Association in this regard showed that for the printing industry paper, the delta density value of the paper under the conditions of black and white backing measured from 0.07 to 0.002, under the same circumstances, the transmission density value It will increase from 0.3 to 1.2. From the data, we can see that the difference between the transmission density of the printing material and the data measured by the same material under different black and white backings has an exponential relationship. The white backing used in this investigation is a non-selectively absorbable material coated with ceramic tiles on white steel, which is non-fluorescent and has a reflection coefficient of 89%. / ISO regulations. In order to actually observe the transmission density value of the paper, the PSI Association investigated several different papers and found that the transmission density value of the thinner paper used for multi-page publications and Bibles is about 0.30; 20 pounds white cloth offset The transmission density of the paper is about 0.60; the transmission density of 80 pounds of coated card material is about 0.90; and the transmission density of 120 pounds of coated card material is about 1.20. These investigations also show that the situation of photographic paper is similar, but with different curves.
Realizing that the black backing minimizes changes in the measurement results, it is recommended to use a standard black backing in the following situations:
· Instrument installation;
· Calibration of the instrument (Note: During the installation of the density meter, the calibration black backing used is very important, because this backing is defined in the ANSI / ISO density standard.);
· Specification of job parameters (for example, printing a job to determine the target point), unless a different backing is specified;
· Industry parameter specification (for example, the printing type of products such as magazine advertisements to determine the target point), unless a different backing is specified;
· Exchange measurement data between different organizations unless a different backing is specified.
For internal users, for example, an operator subjectively estimates an image and compares it with a proof or another model. The black backing will make the printed image look slightly different, which is not applicable at this time. . As suggested in the standard, in these cases the operator is likely to place one or more unprinted substrates under the paper and then evaluate it.
Many members of international organizations plan to develop a standard white backing. The standard of this backing must redefine the following parameters:
· Color · Brightness · Surface diffusion phenomenon · Fluorescence · Density In order to ensure the transmission of the measurement results, each of the above factors should be recorded when using the white backing to ensure that the receiver of the measurement results can understand the operation of these measurement results .
From the two perspectives of measurement standards and user standpoints, the currently used standards have a certain stability, and the convenience of using black backing (existing materials, and common under various conditions, to ensure consistency with the current ANSI standard) And the challenge of defining a white backing shows that the development of a white backing standard will not help to reduce the variation in measurement results, nor will it reduce the user application of standard backing materials.
In general, the industry recommends a standard black backing for color measurement for measurement and process control purposes. This should be a standard method to ensure that these measurement operations are not affected by factors such as printing on the reverse side of the paper or the disproportionate image on the paper. The printing materials should not be stacked together during the measurement. First of all, if a black backing is not used during the density measurement, the user should communicate the information of the backing used, and also be aware that this measurement result is affected by additional changes. The degree of influence of these changing factors can be determined by comparing the measured readings of the same paper material with and without a standard black backing.
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