The quality of the image scanning determines the final quality of the image. How to get the best quality image is a long-term common topic in the industry. The quality of scanning has a great relationship with the scanner, scanning software and the actual experience of the operator. The quality of control is nothing more than the original manuscript, scanning equipment, scanning parameter settings and scanning techniques. In the following, I will talk about some aspects that affect the quality of scanning in combination with work practice. Composite Cookware Set,Stainless Steel Cookware,Composite Pot Set Jiangmen Xinweijie Stainless Steel Products Co., Ltd. , https://www.xwjstockpots.com
1. Manuscript type and manuscript analysis
Faithful reproduction of manuscripts is the eternal pursuit of the industry. Therefore, manuscripts are the prerequisite and basis for ensuring the quality of color reproduction.
1. Color copy requirements for originals
â‘ High definition. It is the basis for realizing the record price adjustment, color, texture, three-dimensional sense, perspective sense, etc .; â‘¡ density contrast. The density contrast of the original must be normal. Generally, the contrast of manuscripts is required to be between 1.8 and 4.0. The levels of bright, middle, and dark tones of such manuscript screens are relatively rich, and the distribution of coordination levels is normal. The color saturation is good and the texture is realistic (if there are rich levels of dark tones; there are few levels of medium tones, you must open the dark tones when scanning, and press the middle tones); â‘¢Color saturation. Check the original under the standard light source (50O0K), the color saturation is the real response to the wave photography scene, only the original with large color saturation can be the original with normal tone; â‘£ image grain. The granularity of the original affects the color, gradation, and texture. The fine-grained manuscript is conducive to the reproduction of gradation and tones (especially the bright texture) and the true expression of color.
2. Manuscripts are usually divided into three types: transmissive, reflective and secondary.
Secondary manuscript: namely, scouring product; the density range is small, the level is not rich, generally only the original large scan, and it is not suitable for enlargement processing. The density range of good quality secondary manuscripts is usually only about 0 to 1.6. Far lower than the density recognition ability of the scanner, only a general flatbed scanner can be used to scan such manuscripts. The second manuscript often has a color shift problem, so proper color correction should be done when scanning. It should be reminded that scanning the second manuscript must be processed on the net.
Reflective draft: ①Photo. The density range of high-quality photos is only O ～ 2.2, which basically meets the pre-press processing requirements and printability; it is the most common manuscript in our daily work. ② Kind.
Transmission manuscript: â‘ negative film. Normally, the negative film is not scanned directly. It is better to develop the negative film into a photo and then scan it. This is because, first, the negative film can not see the effect. It is not easy to restore the color; second, the base of the negative film has a colored light film, which will cause the negative film to have no white field, and it is not easy to calibrate. â‘¡ Positive film (slide show). It was redeveloped by negative film, such as 135 slides. The film base is not as good as the reversal film, the density range is small (0 ~ 2.8), and the particles are rough, the scanned image is also dirty, its magnification can only be controlled at 4 to 7 times, no matter how large, the picture Will be distorted. â‘¢Reversal film, also called positive film, the film material and processing technology used are different from negative film and positive film, the quality is the best in the original, the safety range is between 0 ~ 3.8, and it can be enlarged by ten during scanning Several times, it is the most ideal manuscript.
3. Analyze the original
The operator should have certain experience and manuscript analysis ability, according to the actual situation of the manuscript; set the scanning parameters to obtain the best scanning quality. In actual operation, special attention should be paid to avoid any parameters that are automatically adjusted. Make the picture quality mediocre, and even fail to meet the printing requirements. For color cast pictures. If you have a wealth of color correction experience, it is best to perform corrections by channel during scanning, rather than correcting them in PhotoShop after scanning. [next]
Second, scan preparation
To obtain an ideal threshold scan image, do a little preparation and experiment in advance; not only can save a lot of time in the future, but also can effectively improve the scan quality.
1. Warm up. The scanner needs a few minutes to warm up. The scanner should be turned on 30 minutes before starting the scan.
2. Clean and maintain the scanner regularly. The scanner should be cleaned and maintained regularly in accordance with the requirements of the scanner manual. When the scanner is not in use, it should be covered with a dust cap. Never let the scanner get into the water.
3. Wash your hands before scanning to prevent fingerprints from contaminating the scanned image. Never use your mouth to blow dirt and dust on the glass of the scanning platform.
4. Clean the surface of the object or image used for scanning. You can use an air bag to blow, and you can also clean the surface with water according to the object being scanned, but to avoid damage to the object, especially pay attention not to leave scratches on the surface of photos and films. Pay more attention to protection when cleaning some original artworks.
5. Flatten the original. If you use software to trim the marks caused by the original curling. Will reduce the clarity and quality of the image. Although there are many functions in Photoshop (such as blur and sharpening methods) to process the image, this is not the best way to solve the shortcomings in the scanned image.
6. Approved. Use the calibration software to adjust the image and improve the scan quality. Most scanners come with various approval options to check the light source and
Stepper motor. Run the school uniform option once a day to keep the scanner's force working state stable. [next]
Third, the scanner's input indicators and parameter settings
The difference in scanned image quality depends largely on the input indicators (such as bit depth, resolution, etc.) of different scanners and the settings for each input indicator. Practice has proved that only by correctly setting the scanning parameters of the scanner for different types of manuscripts can we obtain the best color, gradation and clarity of the image and ensure high-quality color reproduction.
1. Resolution
Resolution reflects the richness of image details recorded by the scanner and can be divided into optical resolution (physical resolution) and interpolation resolution (maximum resolution). Optical resolution is the actual resolution of the scanner and the true resolution (vertical and horizontal values) obtained when the scanner is scanned by the hardware. It is a key factor in determining the clarity of the scanned image. Interpolation resolution is the resolution that is enhanced by software operations to enhance the dots. It does not add new information to the image, but it is very useful for images or scanning line drawings with specific requirements. In order to obtain proper image quality, the scanning resolution needs to be matched with the number of screen lines. For the original size copy, the number of forged lines (lpi) is generally multiplied by a quality factor k (1.5 ~ 2.0) to determine the best Scan resolution. For example, when the amount of online money is 175 lpi; if k = 2, the scanning resolution is 350dpi.
2. Bit depth
The number of bits of color information sensed for each pixel in the scanned input image is the bit depth; also known as the sampling depth. It is generally 24 bits, that is, R, G, and B each occupy 8 bits, and each has 256 gray levels; it can represent 2 (8 + 8 + 8) = 17.6 million colors are true colors, and professional scanners should at least There is 36 bits deep. At present, Photoshop can only process 24-bit images, and images obtained by scanners with a bit depth higher than 24 bits need to be converted into 24-bit images before they can be processed in Photoshop.
3. Choose the right black and white field
The brightest point in the picture is the white field. The white field directly affects the tonal gradation of bright tones and middle tones. The human eye is extremely sensitive to changes in bright tones. When the white field is set too bright. It will cause some levels of bright tone to be lost; if it is set too dark, the overall level of the picture will be dark. For general pictures, when the white point is neutral gray, the CMYK value of the white field can be 25, 0%, 0%, 0%. For the case where the white field is a color cast; it must depend on the specific situation, and the ability to judge can only be improved through continuous accumulation of experience.
The darkest point in the picture is the black field. The setting principle of black field is basically the same as that of white field. The difference is that the highlight point can be determined through the eyes, and the black field of the image requires the operator to have a certain judgment. Some scanning software can automatically identify the black field, and some also provide certain tools (such as the adjustment of the histogram) to determine the black field. If the black field is set too dark, it will cause the dark tone level to be lost, causing a "union" phenomenon. . If the black spot is set too bright, the dark tone will be too bright. For large and most normal pictures, the K content of CMYK in the black field cannot be lower than 70%, and generally not higher than 80%.
In general, when scanning, compare the difference between the ink field and the dark tone level, the white field and the light tone level, and judge the scanning effect by comparing the values ​​shown in the "probe". Do n’t easily believe the color effect displayed on the screen