Tips for image processing in newspaper printing
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Photographs in newspapers have a very important role. If used properly, not only can beautify the layout, increase people's interest in reading, but also play a finishing touch. The pictures processed before the print directly affect the printing effect. Therefore, we have made some observations through image processing through years of experience.
Planning approval should be done before scanning the image. The quality of the picture, you should know that there are over-exposed or under-exposed pictures, there is no need to go to the net, the pictures are properly processed during the scanning process, during the scanning process, because the loss of the degree of image processing is minimal.
Processing images In Photoshop, we first need to establish a good image, black and white field and gray balance, these two factors are very important and very necessary. We have different determinations in the black and white field depending on the printing needs. But the standard is black, not white paste can not be absolutely net. However, in order to ensure a better visual effect of the printed image can be considered a small gemstone area network or paste, but not a large area. If the picture is distorted we can balance its color by gray, but the medium gray affects the color reproduction of the entire picture, so it is accurate. Gray balance has the following experience, that is, less than 20% or 80%, CMY values are roughly equal; in the middle part, my value is roughly equal to 10% to 15% of the value, but than my c value .
Picture color scan. If grayscale, the color scan effect will be more color-shifted grayscale maps than direct scan grayscale, especially more than 70% color saturation. There is a "dash" option, if you need to select a value printed on the higher the number, the higher the printing accuracy of the picture selected in the finished linocolorelite settings panel. In addition, the "color correction" option, you can choose the default, you can choose according to your own situation. The "Color Assistant" calibration "is a good tool to choose a different way, or to determine the selected value of the image for free, and to adjust the data during the image scanning process to retain more levels and details.
In actual operation, grayscale processing is relatively simple. There are two ways to convert a Forex color image into a grayscale image: use the "mode" function to convert directly; or you can convert the color image to Lab mode, then delete the channel "and" b", and finally convert the image into "gray" In the chroma Lab mode conversion, the brightness L channel retains more level changes, so the effect will be better. The gray picture will be a good black and white, which is to pay attention to the horizontal picture halftone must be turned on Otherwise, the picture will feel dirty and the contrast of the midtones will increase, which will significantly improve the situation.
We feel that when using photoshop to process images, don't let the image and the two modes open. Because, once every conversion, the details of the original image will be lost. When the image of the RGB mode is converted into a CMYK mode picture, the color separation parameter plays a decisive role in the effect of converting the picture. The adjustment of the color separation parameters will greatly affect the conversion of the picture. The Photoshop image processing software has the ability to control the color separation parameters, that is, when the image processed in the RGB mode is converted into the CMYK mode output, the color conversion loss in the image mode can be reduced by adjusting the color separation parameter during the conversion process.
The rgb mode image is converted to CMYK mode, plus an intermediate step on the step, which is first converted to Lab mode. The Lab mode consists of three channels, the L channel represents brightness, which controls the brightness and contrast of the picture, including the color of one channel from dark green (low brightness value) to gray (brightness value) to bright pink (high brightness value). The b channel includes colors ranging from bright blue, gray (low brightness value) to burnt yellow (high brightness).
A color blend similar to Lab mode and RGB mode will produce brighter colors. Only the value of the luminance channel affects only the change in hue. The rgb mode of the Lab mode adds two channels of the luma channel mode. Lab mode is device-independent, and you can use this mode to edit any image (including grayscale images), as fast as RGB mode, and multiple times faster than CMYK mode. The Lab mode ensures that there is no loss of color in the CMYK range when the color mode is switched.
Processing images will have different effects, and it is helpful to increase the contrast of the picture in different modes, such as LAB mode, just use images that are not too large in amplitude, otherwise would be distorted. It is the best RGB mode for processing pictures, the saturation and brightness of photos, the level of performance and other functions are very good, especially good at adjusting the color of a person's face without causing distortion or level. All the pictures just had to be converted to CMYK mode before printing, so adjust the advantages of the picture and CMYK mode. In this mode, it is convenient to adjust each color channel to prevent image color cast to determine the black and white field.
Different pictures require different methods, such as Chinese paintings and similar pictures must be faithful to the original film, and can not change its color, because of the good results. The details of the comic calligraphy are not lost. You can consider using a bitmap. The clear capacity of the picture will increase the speed of the order.
In addition, in the Photoshop adjustment of the image, "there are many utilities, such as "brightness/contrast", "hue/saturation", optional color, etc., in actual work, as long as it is used reasonably, you will get a good result.