How many original correction functions does the ho

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How many original correction functions does the scanner have

when using the scanner to scan images, most operators only adjust the options such as resolution and zoom ratio, and the rest adopt the default settings. Practice has proved that this can not obtain the best scanning effect. Especially when the original image is defective, the scanning result is even worse. When scanning defective images, how can we give full play to the best performance of the scanner and scan high-quality images? This requires careful analysis of the original, make full use of some original correction functions provided by the scanner, and carefully adjust the preset values of the scanner

first, pictures with inaccurate exposure

brightness and contrast should be adjusted during scanning. Overexposed pictures look white because of their high brightness; The underexposed picture looks black due to its low brightness. At the same time, the images are lack of hierarchy and rich in detail. At this time, we can drag the slider on the brightness and contrast slider to make the brightness and contrast of the image moderate. Since the adjustment of brightness and contrast works on all pixels in the image, you should pay attention not to lose one thing and lose the other. For example, the main information of the picture is located in the darker area, making it brighter can make the details more obvious. However, when the brightness adjustment function is used to brighten all areas, all details in the areas with higher brightness will be lost

second, color biased pictures

color balance should be adjusted during scanning. If the image is somewhat biased, you can use the color balance option to change the overall tone of the image. When the color deviation is not serious, you can choose the "automatic color balance" option to let the software correct automatically; Manual adjustment is required when the color deviation is serious. The color of the scanner is mainly a mixture of red, green and blue. The scanner provides adjustment functions for these three basic colors, with red, green and blue sliding bars in the adjustment options. To adjust the color of the image, just drag the slider on the slider that the author has randomly investigated the effective travel of the electronic tensile machine sold on the market to the color to be added to the image, or drag the slider away from the color to be reduced. Color adjustment requires mastering some knowledge of chromatics, especially the principle of complementary colors: the two colors in relative positions on the color wheel are called a pair of complementary colors, such as red and cyan, green and magenta, blue and yellow are complementary colors to each other. The so-called complementarity is that the reduction of a color in the image will inevitably lead to the increase of its complementary color. It is absolutely impossible for a color and its complementary color to increase or decrease at the same time

III. pictures lacking levels

the gamma value should be adjusted during scanning. The gamma value affects the hue of the middle value of the graph or the gray level of the middle level. By adjusting the gamma value, the brightness value of the gray scale of the middle tone of the image can be changed to increase the middle level of the image, without having too much impact on the levels of the dark and bright parts. Entering a number larger than one will expand the range of intermediate tones, which can make the image with a large proportion of intermediate tones produce less contrast and more details than synchronous belt and ball screw pair transmission. Entering a number smaller than one will narrow the range of the middle tone, which will increase the contrast of the image and reduce the details of the image. When the curve moves downward, the corresponding pixels of the image become dark; When you move up, the corresponding pixel lights up. Its adjustment often needs to be used together with brightness and contrast to achieve satisfactory results

IV. pictures with poor composition

should be cut reasonably during scanning. Pictures with improper framing often have messy backgrounds, unobtrusive themes, or skewed scenery, resulting in poor visual effects. When scanning, you can choose the scanning range to choose or reject the original image, correct the skewed image, and recreate the art according to your needs. The specific operation is to select "scanning size" as "user defined" in the scanning setting option, and then select the area to be scanned by dragging the selection box in the preview image window. The method is: press and hold the left mouse button at the corner of the area to be scanned, drag the selection box to the opposite corner of the scanning area, and release the left button. In this way, the scanner will automatically scan only the selected area. For pictures with skewed scenery, just use the "rotation" function to correct them

v. printed pictures

the function of removing wrinkles should be used during scanning. Hanging printing technology is used in the printing field, which relies on countless dots of different sizes to show the brightness of the image. These dots are acceptable to the naked eye, but it is a problem that cannot be ignored for the scanner, because when the scanner scans the printed photos, it will scan these dots, which will affect the quality of the image. By analyzing the image with dots, the de technique can restore it to the original without dots and reproduce the effect of the original image. Scanners generally have several options for us to choose from. When the original image is a magazine or film covered printed matter, please select "magazine"; When the original picture is a newspaper or a rough dot print, please select "newspaper"; When the original image is a high-quality exquisite print, and the point is very small, please choose "art print". It should be noted that there is no throttling loss and overflow loss. If scanning non printed matter, select "no setting" and do not turn this function on, because it will reduce the quality of the scanned image

by modifying the scanning parameters, we can make up for some deficiencies of the original image and appropriately improve the scanning effect, but the effect is always limited. To get the ideal scanning effect, the best way is to choose a good picture

VI. pictures downloaded from the Internet

because most pictures downloaded from the Internet are in RGB mode, and the color range of RGB mode is larger than that of CMYK mode. In order to ensure the printing effect of images, it is best to use RGB mode for processing, and finally convert to CMYK mode. Select the CMYK preview option in the View menu when viewing RGB mode images in Photoshop. That is to say, the image is displayed in RGB mode and CMYK mode. Because most of the downloaded images are of display size, the area is small. When we want to make the image needed by the newspaper, the image will become not clear enough. If there are mosaics, we should pay more attention to not sharpening too much when sharpening, and properly blur them before sharpening. If the original image is a color image, but it should be used in the grayscale layout, do not directly convert the original image to grayscale mode during processing. RGB mode should be used for processing. First convert the processed image to the image in L * a * b * mode, and then select the image in L * channel as the gray-scale image for printing through the channel separation command. Pay attention not to switch between RGB and CMYK modes, let alone turn the two modes around, because in the dot matrix image software, every time the image color space is converted, a part of the details of the original image will be lost

precautions in the processing of paper printed images: in order to make the color bright, the main color should be appropriately emphasized, and the opposite color should be appropriately reduced or not used; Appropriately discard the dark tone to maintain the medium and bright tone; The face value of the black-and-white image of the character should not be too high to avoid being too dark. The brightness should be done enough

in short, there is deep knowledge and experience in the scanning and production of images in the prepress system. Therefore, the operator of the prepress system must be able to master various skills of image processing, improve his aesthetic outlook, accurately judge the quality of the picture, and really get a good picture printing effect. Don't be afraid of trouble, carefully adjust, and strive to achieve the effect that the processed picture is of higher quality than the original

source: Qingdao newspaper group Author: Zhao Li

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