Printing machine properties file (below)

3, The maximum density in the field, the minimum expansion of outlets, and the best performance of gray balance. These 3 points are related and attached to each other. Here we discuss together. First of all, one of our important principles is to ensure the best In the gray balance state, the minimum dot gain rate is obtained and the maximum solid density is determined. In the four colors, the black version is considered independently: we must first determine the density of the black version because the density of the other three colors is gray. Balance is related to each other and is based on the grey balance of the black version.

In modern offset printing, we require that the density of the black plate be as large as possible, but due to the ink-water balance of the printing press; too thick ink layer thickness will bring ink adhesion to be what we often say, because the black ink has the highest viscosity. The possibility of a paste version is the greatest. In the figure above, we demand that the finer the anti-white lines in the image, the clearer the better. When the black ink volume is increased until the 0.01 point line is just about to be pasted, the black version of the field density can be Think of the greatest density.

We visually require that the black ink gradually gradation shape without a ladder, the darkest part does not paste version, for the black version, we can appropriately increase the dot expansion rate of it, in order to get a darker black, so the required 50% The dot expansion does not exceed 15%, that is, the measured value is below 65%. Usually, after satisfying the above conditions, measuring the density of the black plate is the maximum black density that we will set, generally about 1.7-1.9.
After we decided on the black version, we decided to determine the maximum density of the other 3 colors: see the top area of ​​the test chart:

Here are mainly two gray strips. The gray strips above are three-color (CMY) gray, and the lower ones are monochromatic black at 50% gray. Now we require that the density of the three colors be adjusted when printing, until the two grays do not matter. It is very similar in hue or brightness. After two grays are close to one another, we measure the halftone dots of CMY three colors at 50%, and require the dot gain rate to be less than 12%, ie, less than 62%, while observing them. The three color gradient steps, like the black version, require gradual and symmetric no-step shape. At this time, the three-color field density values ​​are recorded, and they are taken as the maximum density. Generally, the three color density ranges are: C=1.5- 1.65, M=1.4-1.55, Y=1.2-1.4,

There is another area on the test chart to check the gray balance. It mainly checks the gray balance at different gradations, indicating that the three colors (CMY) are gray at different tones (7%, 30%, 60%, and 80%, respectively). The proportion of numerical values, we find the best gray balance of the color blocks, the so-called optimal gray balance is required and monochrome black version of the same tone of the gray color, so long as the three-color gray block is closer to the figure in the red diagonal Line, then the gray balance of the entire printing is more standard, now we have the maximum density of the four inks, the maximum amount of black ink and the maximum amount of ink.

4, printing accuracy, overprinting accuracy is the most basic printing requirements, but it is also an important factor in our color management, to eventually become a color standard, the accuracy of the color is very important, offset printing four color dots In a certain degree of standardization and arrangement, when the overprint between the color plates fails, it will seriously affect the color rendering effect of the print colors. We require that any two color edges in any direction cannot be exposed.

So far we have basically adjusted our printing presses or we can say that we have completed the standard adjustment work of the printing presses. There are still some photographic works in the test chart that can be used to observe the actual results after adjustments. These figures have certain representations. Sex: There are dark pictures that reflect the levels of the shadows; high-profile photos that reflect the level of the highlights, and scenery, etc. You can judge the correctness of these photos based on your own experience.

Next we can use these printed standard data to guide the printing of our standard color target documents.

Sixth, now we enter the main task: according to the above printing standards to guide us to print standard color target files, first select our color target, generally we can print IT8.73, can also print ECI2002R if it is Use GMC software must use ECI2002R, if it is other ICC-based color management is recommended to print IT8.73 file, too many color blocks based on ICC profile digital proofing is not a good thing! Things to note are:

1, according to your measurement tool to determine the arrangement of color targets, different measuring instruments have their own color arrangement, porfilemaker provides these different arrangements of the map file.

2. Attention should be paid to the position of the figure on the printing plate, and the center of the printing plate should be placed as far as possible while avoiding the pause position of the printing ink stick. The new type printing machine can conveniently adjust the staying position of the ink stick in the operation window. Some old models are very troublesome to adjust.

3, printing must be accurately registered, the importance of which has been mentioned above.

4, but also strictly in accordance with the color density determined by the previous test to print (assuming we previously set the four-color field density is K = 1.9, C = 1.6, M = 1.55, Y = 1.4), then when printing The error should not exceed 0.05 of this standard density.

5, within the entire color target range, the same color about the density error can not exceed 0.05! (Assuming C color density standard = 1.6 then C color density must be controlled between 1.55-1.65 across the entire color target! Remember this is very important!!!)

6. After adjusting the machine and color, let the machine open more than 200 pieces all the way, take the last 10 pieces, and measure the density value of the printed matter that is closest to the standard density value.

7, OK, you have finally got a standard printer color characteristics of the color draft. ,

Seventh, measurement: there are many tools for measuring software. Experts who are skilled in using these tools and software are more here. I will not repeat them. I usually use profilemaker+lino/scan to measure, use printopen to test, and then profilemaker To generate ICC, I would like to talk about the calibration of measured data, and the problem of setting ICC profiles. These two points are easily overlooked. Let's take a look at the calibration. Is it a certain standard? Is it consistent with our expected printing standards? This requires us to make a judgment on the measured data. Do not rush to generate the ICC after measurement. Save the measurement data as a TXT data file. Here is a useful function in printopen, which is used to check the measurement. The data: We opened printopen, clicked on a new curve, then opened a data file and selected the TXT file generated by our previous measurement.

After opening, we can first see if its gamut range is normal, and then focus on checking the expanded dot curve after the measurement.

Is the checkpoint spread within our ideal range? Does each curve's dot enlargement occur at 50% of the maximum? Is the parabola smooth? And so on, if there is a problem, we can use manual measurement of the standard print to determine The question is whether it is on the top of the measurement or on the printing. Before we generate the curve, we must make the data obtained accurate, not defective. Only the ICC characteristic curve based on the correct data is valuable!

Eighth, finally generated: After the data after the appeal test, we then transferred to profilemaker to generate the ICC curve. Here we should pay special attention to the setting of the separation method. This will affect the application of the ICC behind, because this curve we Not only for digital proofing, it will be the essence of our color management system! It also guides our screen soft proofing, matching color separation!

In general, UCR is to allow a small number of black version to participate in color separation, if you want to copy color pictures, you have to choose UCR, which can make your picture color purity higher, such as the human skin color we do not want to Involving the black version, there is no doubt that UCR should be our first choice.

Here I suggest that you use GCR to generate another ICC, because when you do some works with black and white keynotes, more black version of the intervention allows you to ensure that the tone is consistent when printing, like black and white with a cool tone Photographs, traditional Chinese paintings, etc. must be separated by color separation using GCR.

Then we need to input your maximum black ink volume and your maximum total ink volume according to the characteristics of your press. The total ink volume of c, m, y, k is also based on the data on the printed measurement chart!


Source: Chinese Printing Community