Questions to consider when choosing a scanner

There are many types of scanners available today: platform-type, slide-type, transmissive document scanners, and drum type. Where do you start? 1. The types of images we need to scan are the following types: * Slides * Transparency (from 2.25*2.25inch to 8*10inch) * Negatives * Prints (to 8.5*11.5inch) Recommendation: Consider, The company's business development in the previous year and forecasting future needs. It is important to remember that general considerations are key issues when selecting scanners. 2. Magnification Considerations Recommendation: The smaller the original, the more data it needs to extract to amplify it. To reach a web of 5*7 inches or more, typical 35mm and 2.25 inch transparencies must be scanned at a resolution higher than 2000dpi. This uses a high-end scanner that automatically selects the resolution based on the magnification. 3. Characteristics of Batch Scanning Recommendation: Units that are busy at work need to process many images at once: and various manuscripts are often mixed together. We can scan only one image at a time on the platform scanner. You can purchase a high-end scanner with a batch scanning function so that the originals can be scanned with different resolutions and different scanning parameter settings. But it does not mean that this function is definitely needed. 4. Production Capacity Recommendations: If our business requires a rapid production cycle, we need a single-scan high-end scanner. Most platform scanner users purchase higher-priced premium scanners for better productivity and higher quality. 5. Stable image quality recommendations: Drum scanners and high-end platform scanners that use special technology can guarantee authenticity over the entire image area: Ordinary platform scanners can lose important edge information and often require After several tests, the correct scan results can be obtained. 6. Dynamic Density Range Recommendation: PMT technology enables the drum scanner to capture the maximum amount of detail in shadow, skin, and highlight areas. 7. Convenience to use Recommendations: The scanner hardware is only part of our production considerations, and the software that drives the scanner is critical to the overall productivity. Therefore, when selecting a scanner, we must choose a suitable software package so that we do not need too much experience, we can do our work, and we can stably obtain good production quality. 8. Color guidance advice: Is it a CMYK color template? Select a set of software that provides color correction guidance to instruct us to perform a complete scanning process, or we can automatically evaluate each image for us and automatically correct the image. 9. Upgrade Feature Recommendation: Do not choose a design mode that requires expensive hardware updates to reach the current level. Choose a design mode device that is really likely to be upgraded through software improvements. 10. Considering the average failure time of the light source Recommendation: Most scanner vendors will not provide this parameter. However, we should ask about the failure time of the light source, because if the failure time of the light source is very low, it is possible that we always need a lot of overhead to replace the light source. This is not appropriate. So, pay attention to this detail at the time of purchase. 11. Professional color tool advice: Do you need more control over the image? Do not use incomplete scanning software. To use software that allows us to easily perform some adjustments, such as balancing chromatic aberrations, adjusting the color saturation in highlights and shadows, and creating user color curves, feedback the adjusted results on the screen. 12. Fees Considerations Recommendation: If we send more than 10 originals per month to scan, then there is a cost-saving way to buy a high-end scanner and use it to make other people's money. 13. Suggestions for future plans: Although the issue of costs may only be a temporary issue, do not use it to do unnecessary things: The first consideration is whether the purchased equipment will increase the scope of our business, rather than hinder the business. . The Seven Steps of High-End Scanning Do you want to get the best scanning results from desktop color scanners? The following steps will tell you how to do it. Happily, many of today's platform color scanners can scan more than 24 bits of color. This color scheme can only describe 8 bits of each color at each point. Many scanners can now describe each color of each point in 9, 10, or 12-bit mode. The bad news is that the scanner must discard more than 8 digits of other digits and produce 8-bit color when output. The problem lies in the fact that Photoshop image processing software cannot adjust the tone and color of images with more than 8 bits per color. However, we can use the scanner software to adjust the image so that all the data captured by the scanner can be used. In acquiring high-quality scans, four basic software tools are valuable: a histogram (a block diagram of the number of pixel points corresponding to gray levels), and a screen densitometer (pixel points below the mouse points) RGB, CMYK or grayscale values ​​for digital display); Grayscale control tool (for setting white point, black point, and gamma dialog box); Curve control (can be performed by changing the position of the point on the curve, Like dialog box for adjusting the shape of a tone curve). Most scanner software has at least three of them. Because most graphic makers are familiar with Photoshop software, we discuss how these tools work in Photoshop. In Photoshop software, there are histogram commands, pixel signal display templates, gray level commands, and curve commands, respectively. The experience of using these tools in Photoshop allows us to understand how to control these tools. The lessons we learned in Photoshop can be easily transferred to scanning software. When we use these tools, we can store the grayscale or curve settings of the image separately, so that we can try these effects on different images. As long as we have applied grayscale and curve conversion to the image, select the Undo command to return to the original scan state. We can also use the Undo command between the original scanned image and the transition effect to compare the processed image with the processed image. If we already have an idea of ​​what the scan has to do in Photoshop, we can go back to the scanning software and rescan the image. The settings for the scan should be as close to the adjustment of the image in Photoshop as possible. After a while, we can see that the result of the scan is very close to the ideal result, because we have fully utilized the scanner's control functions. Resolution Solutions There are four issues we have to consider when scanning an image: resolution, color balance, gradation range, and sharpness. First, let's take a look at the resolution, and the remaining three will be discussed later in the article. The resolution we need depends on the size of the original image, the finished size we need to copy, and the output method we want to use. For halftone output, whether it is a laser, ink jet printer, thermal wax transfer printer, or a film for a laser imagesetter in a press, the general rules followed are simple: for output size images, every inch The pixel number is between 1.5-2 times the screening frequency used. For example, the scan frequency of our scanned image is 133 lines per inch and the output resolution of the image should be between 200-266 ppi (pixels per inch). The conservative approach is to multiply the line by 2 times - we may be lucky to get a low resolution, but because it does not use the high resolution necessary. We multiply the output resolution (twice the number of screens) by the scaling factor (the ratio of the output size to the input size) to calculate the input, or scan resolution. For example, if you want to copy a 1*1.5-inch (35mm) original into 6*9 inches and use 150 lines/inch of screen, the formula should be the number of lines*2*(output size/input size), or 150* 2*(6/1)=1,800. It does not matter what size is substituted in the formula. As long as it is the corresponding input, the output will be fine. If the object being scanned out is a continuous tone device, such as a continuous tone scanner or a dye sublimation printer, we only need the output resolution to correspond to the scan resolution. So the formula for scanning resolution becomes (output size/input size)*output device resolution. Before fixing the color balance, we should first determine the correct tone range. If the scanning software allows it, we can save the adjustment parameters into a settings file and go back to adjust the tone, then apply all the settings at the same time. Or it doesn't allow it, just do a single step in Photoshop. Once you have the correct colors and colors, you can emphasize the sharpness of the image. The following seven steps tell everyone how to get a good gradation range of the scanned image, and correct color balance to get a clear scanning effect. 1. Understanding the histogram It is one of the most important tools for analyzing the scan. With a glance, we can understand many of the scanned images from the histogram. In Photoshop, you can see the histogram in the Level command dialog box. If there is a sharp peak in the dark tone area at the end of the grayscale scale, the darkness of the scanned image is lost. If the peak appears on the right side of the grayscale scale (highlight area), it means that the details of the highlight area are lost. The histogram of the correct scanned image has several pixel points relative to the darkest tone (0) and the brightest tone (255). 2. Try to set the adjustment work in the scanning software. Complete the adjustment of tone and color balance before scanning. If you make adjustments after scanning, you can only use 8-bit color images, and each adjustment will lose part of the image information. Assume that the Scan Gamma value is set to a histogram display of 1.4 scans. The scan image contains information on each level of 256 gray levels of 8-bit color. The gamma value controls the correspondence between the input gray level and the output gray level. When the gamma value is greater than 1.0, the midtones are highlighted; below 1.0, the midtones are darkened. If you scan an image with a gamma value of 1.0 and then correct it to 1.4 in Photoshop, the dark tone area at the end of the gray scale may lose tone levels. If a comb structure appears in the figure, it indicates that the piece of information in the figure has been highly contrasted. 3. Use the Level command instead of the Brightness and Contrast function to use brightness/contrast control to brighten the image, just an inducement. Because if the brightness/contrast function is used, the brightness and darkness of the image will be lost because of some simple upward or downward movement of the brightness range of the image. Figure 3a shows a good exposure but some dark images after scanning. If we simply brighten the brightness of the image, we will get the effect of Figure 3b - all highlight details are lost and many solid white spots appear. If you use the gray level command, we can adjust the brightness of the midtones without losing the details of the dark and highlights. If we have to adjust the image in Photoshop, the value of 1.2 is the maximum gamma adjustment we recommend for post-scan adjustment. If it is far greater than it, it will produce high contrast tones in the image. 4. For more fine-grained adjustment, use the curve command to do everything we can do with the gray level command, all with the curve command, and the curve function is more powerful. When we adjust the gray level (gamma refers to the gamma value of the midtone of the image input), what we are actually doing is bending the curve around a point on the midtone of the curve. The curve command allows us to fine tune the range of the gradation. When you want to move a point on a curve, it is often helpful to set two points on both sides of this point to support this curve. This controls the movement-induced changes to a small range. If we do not do this, we will change the shape of the entire curve, and the result may be quite large. 5. Set the gray balance once using the curve and information template (Info)