Pictures have a very important role in the layout of newspapers. If used properly, they can not only beautify the layout, increase people's reading interest, but also play a finishing touch. The processing of a picture before printing directly affects the effect after printing. Therefore, through years of practice, we have conducted some useful explorations on image processing.
Before scanning a picture, you should review it first. As for the quality of the picture, you should know what you want, that is, whether the exposure of the picture is excessive or insufficient, whether you need to go to the Internet, etc., so that the picture can be properly processed during the scanning process, because the picture is processed during the scan The loss of hierarchy is minimal.
Generally pictures are scanned in color. If it is a grayscale image, the color scanning effect will be better. The grayscale image converted from color is more hierarchical than the grayscale image directly scanned, especially for colors with saturation above 70%. There is an option of "line" on the localized Lino Color Elite setting panel. If it is a printed matter, you need to select a value here. The higher the printing accuracy, the larger the number selected. In addition, 6 options such as "color calibration" can be selected by default and can be selected according to their own circumstances. The "Color Assistant" in "Calibration" is a very useful tool. Choose different methods for the picture, or freely determine the selected value. Adjusting the data during the picture scanning process will retain more levels and details.
In Photoshop processing of pictures, we must first set the black and white field and gray balance of the picture. These two factors are very important and necessary. According to different printing needs, the determination of black and white fields is different. But the standard is that the black field cannot be confused with the white field. However, in order to ensure better visual effects after printing, you can consider a small area of net or paste, but it must not be a large area. If the picture is distorted, we can restore its color by gray balance, but the medium gray affects the color of the entire picture, so it must be accurate when used. There are several experiences in mastering the gray balance, that is, below 20% or above 80%, the CMY value is basically equivalent; in the middle value part, the MY value is basically the same, but the C value is 10-15% more than the MY value.
In practice, the processing of grayscale images is relatively simple. There are two ways to exchange a color image into a grayscale image: directly use the "mode" function to convert; or first convert the color image to Lab mode, then delete the "a channel" and "b channel", and finally convert the image into & "Grayscale". In the chroma Lab mode conversion, the luminance L channel retains more gradation changes, so the effect will be better. After setting the black and white field for a grayscale image, you must pay attention to the layer of the image, and the midtones must be pulled apart, otherwise the picture will have a foggy feeling, dirty and unclear. Increasing the contrast of the midtones will obviously improve This situation.
In the process of using Photoshop to process pictures, don't let the pictures move between the two modes. Because every time you convert, you will lose some of the details of the original picture. When converting an RGB mode picture to a CMYK mode picture, the color separation parameters will play a decisive role in the effect of the picture conversion. The adjustment of color separation parameters will greatly affect the conversion of pictures. Photoshop image processing software has the ability to control color separation parameters, that is, when it is necessary to convert an image processed in RGB mode to CMYK mode for output, adjustment of color separation parameters during the conversion process can reduce the Color is lost during mode conversion.
If the RGB mode picture is converted into CMYK mode, an intermediate step is added to the operation step, that is, the Lab mode is converted first. The Lab mode consists of three channels, the L channel represents brightness, and it controls the brightness and contrast of the picture. The a channel includes colors from dark green (low brightness value) to gray (medium brightness value) to bright pink (high brightness value). The b channel includes colors from bright blue (low brightness value) to gray to buffy yellow (high brightness value).
Lab mode is similar to RGB mode, and the blending of colors will produce brighter colors. Only the value of the brightness channel affects the lightness and darkness of the color. The Lab mode can be considered as a mode of two channels of RGB mode plus one brightness channel. Lab mode is device-independent. You can use this mode to edit and process any picture (including grayscale pictures). It is as fast as RGB mode and several times faster than CMYK mode. Lab mode can ensure that there is no loss of color in the CMYK range when performing color mode conversion.
Processing pictures in different modes will have different effects. Lab mode is helpful to increase the contrast of the picture, but the amplitude cannot be too large, otherwise the picture will be distorted. RGB is the best mode for processing pictures. It provides photos with saturation, brightness, and performance levels. It is especially good at adjusting people's facial colors without causing distortion or loss of levels. However, all pictures must be converted to CMYK mode before printing, so adjusting pictures in CMYK mode has advantages. In this mode, adjusting each color through the channel can prevent the picture from being discolored, and it is also convenient to determine the black and white field.
Different pictures require different processing methods. Pictures such as Chinese paintings must be faithful to the original film, and you cannot change its color because the effect is good-looking. In addition to ensuring that the details such as comics and calligraphy are not lost, you can consider using bitmaps, which are both clear and have a small image capacity, which will increase the speed of haircutting.
In addition, in Photoshop, there are many useful tools in "Image Adjustment", such as "Brightness / Contrast", "Hue / Saturation", "Selectable Color", etc. In actual work, as long as it is used reasonably, it will be very good. effect.