Site realize, print product, can reflect, publish surface level wait for and the intersection of color and steps transfer deeply or lightly ‘ Light and shade) Base unit with natural boundary. It plays the decision and prints the product color, function of the level and image outline in press. So only as big as site to could reproduce color of the original manuscript while being faithful while being accurate make a plate, guarantee the printing craft makes better result.
Behave by size of the site because of printing the deep or light intensity of the product layout, the site of the area of different size, is commonly called as ” becoming ” on crafts . Only understand the concept of the site round number accurately, could use the site to be printed off and most close to the seal product of the color of the original manuscripted well. So, print the knowledge that operators and quality testing personnel should know in round number which knows the site. Describe several kinds of site round numbers as follows briefly now:
Distinguish fifty percent less than round number of site, to can hold equal black drop of site count, come on, recognize according to the intersection of opposite side and two space between being black. Namely in the space between two black sites of the opposite side, can put the black sites of three drops of equal size, a site become; If in the distance between two sites, can hold one Liang of likewise large sites, called twenty percent of the sites; If between two sites Yes 1 is put. The sites of 5 grains of equal size, are named thirty percent of the sites; Can hold 1 if between two sites. 25 sites of the same size, are called forty percent of the sites; Can hold a site of the same size if between two sites, that is to say black point and white point each take half in the unit area, it is fifty percent of the sites. And fifty percent, in order to discrimination to go site, with can hold how much of the same size white point come on, weigh between the the intersection of opposite side and two white point. According to arranging the law in the site, networks held count in two white point interval, just sixty percent are the same as forty percent; Seventy percent are the same as thirty percent; Eighty-percent are the same as twenty percent; Ninety percent become the same with 1.
The above-mentioned situation shows, the so-called site round number is the percentage accounted for in the unit area. If 1 become site 10%, 2 become 20%, the others analogize, 100% are the layout on the spot. Arrange the rough analysis of the situation from the positive site, if black point is greater than the white point, it is fifty percent, in order to go to the site; If black point is smaller than the white point, it is under fifty percent site. The denser the site round number crosses the black of product layout of great seal, simple on the contrary. The size of the area of site, has determined the change of the layout level. Usually the level on the picture is divided into three steps and adjusted the level, namely the lofty tone level makes up by 1 to thirty percent of the sites, form the bright position on the picture. Adjust the level and display the light and shade transition position of the picture in the middle, usually 4 to sixty percent of the sites make up. And the dense dark picture composed of 7 to ninety percent of the sites is the low-key level. Print the most bright place on the layout, the high mere part is that 1 becomes the following sites.
In sum, only know the round numbers of the site accurately, could utilize the site to change the law well, produce the printing plate which accords with the original manuscript, print off the color printing products with accurate color, with satisfactory quality, this is exactly a goal of quality control too.