In the packaging and printing industry, printing manuscript plate making needs four-color electrical separation. Apple computer color separation originals include reflection originals (such as color photos, originals, watercolor paintings, oil paintings, traditional Chinese paintings, New Year paintings, gouache paintings, etc.) and transmission originals (such as color reversal films (natural color positive films), color negative films, etc.).Relevant adjustment requirements before printing.
The brightness of the color negative original is opposite to the original, and the color is complementary to the original. For example, the opposite color of red complementary on the negative is green, the opposite color of yellow complementary is blue purple, and the opposite color of red complementary is blue. The light and shade on the positive manuscript are the same as the original, and the color is the same as the original.Relevant adjustment requirements before printing.
Printing copy is a visual image formed under the action of transmitted light. A reflected original is a visual image formed by the reflection of the original under the illumination of a light source.Relevant adjustment requirements before printing.
The scheduling of printed matter is to classify the color according to the brightness. In the copy operation of printed products, the color recovery, scheduling recovery, texture recovery and clarity recovery must be achieved. The color recovery is that the color tone is correct, and the copied product perfectly reproduces the color of the original without color deviation and variegation.Relevant adjustment requirements before printing
Ideal step restoration means that the steps on the manuscript are faithfully restored on the printed products to meet the copying requirements of the manuscript. The maximum recording density of printed matter is 1.8. After reaching 1.8, it becomes a straight line parallel to DT (original density). Therefore, both reflected and transmitted originals must be adjusted to compress and contrast, correct color difference and reach the range suitable for printing and copying stage.Relevant adjustment requirements before printing
For example, the maximum density of a color original is DT = 3.0, and the maximum recording density of a printed matter is Dr = 1.8.
The curve shows that the copy of the printed matter does not reach the maximum density of the original. The materials used in the process of printing include ink, paper, photosensitive materials (software, PS version), color sequence, printing machinery, etc. the maximum recording density Dr = 1.8, but DT = 3.0. The maximum density of the original is large and can only be compressed and compared. Otherwise, the actual effect cannot be printed.
Printed matter often needs to be adjusted step by step when it is gradually restored. When the density contrast of the manuscript is greater than the maximum recording density of the printed matter, in order to make every step of the manuscript reflected on the printed matter, the original work must be adjusted at appropriate stages. Relevant adjustment requirements before printing
Secondly, in order to meet the copying requirements of special originals (for example, photos with bright tone as the center and photos with dark tone as the center), the stage of the original must be properly emphasized and other stages must be compressed accordingly. The main feature of linear compression is to adjust the equal proportion of each step. Linear compression does not represent the real visual equal proportion compression, because the D-Y curve is also nonlinear. After this compression, the bright adjustment is not easy to be distinguished by the human eye, resulting in the “gray level” phenomenon.Relevant adjustment requirements before printing
Tone reproduction refers to the relationship between the original density and the percentage of reproduction dots.Relevant adjustment requirements before printing
To make all levels and colors on the original can be well expressed in the printed matter, first select the correct hierarchical curve. Hierarchy is the basis of order and color change. If the hierarchy on the picture is not rich, the color performance must be monotonous and tasteless. Only if the hierarchy is realistic, can there be vivid color change.Relevant adjustment requirements before printing
Absolutely faithful reproduction of the original is impossible, because most of the original density contrast is greater than that of the printed matter, so the printed matter reproduction must compress the density. Therefore, it is necessary to lose the subtle level of the part. In practical operation, the reasonable level curve should be adjusted according to the contrast of the original and the specific content of the tone, that is, the levels of the secondary parts above both the reflective and transmissive manuscripts should be compressed, so that the levels of the main parts can be emphasized and characterized.Relevant adjustment requirements before printing
On the premise of normal comparison of color manuscripts, the hierarchical curve is accurately adjusted according to different types of manuscripts. The control level of apple computer for extension and color separation is convenient and flexible. Although it can be locally strengthened or compressed, attention must be paid to the balance of the hierarchical curve of the color splitter. Relevant adjustment requirements before printing
The balance of neutral gray is appropriate, and the incorrect hierarchical curve will distort the replica. Therefore, please pay special attention to the correct use of the horizontal when operating the motor and apple computer, but the overall color deviation of the original can be corrected by adjusting the horizontal curve.Relevant adjustment requirements before printing