How to Maintain Image Accuracy in Large Format Color Output

Obtaining high-quality output in large-format color output must pay attention to the source file quality There are two main ways to obtain the source file. One is to scan the material and the performance of the scanning device has a decisive influence on the quality of the generated file. The quality of files obtained by different devices scanning the same material is not the same. Another method of obtaining the source map is to directly select from the ready-made electronic picture library. At this time, the user cannot select the source map accuracy.

In theory, the accuracy of the source file should be no less than 1/4 of the output accuracy in the case of 1:1. If a 1010cm photo is to be enlarged to 100100cm at 720dpi, this photo should be scanned at a resolution of not less than 1800dpi (calculation formula: source file dpi = magnification factor X (output dpi/4)).

If the accuracy of the source file is less than 1/4, the image will have a more obvious graininess, affecting the picture quality. If it is too large, the file will be too large, affecting the speed of drawing.

In actual use, the user often encounters such a problem. When scanning a photograph, the accuracy of scanning needs to exceed the mechanical resolution of the scanner. At this time, the user only needs to use the scanner's highest mechanical resolution to scan the entire photo, instead of using the software interpolation function of the scanner to improve the accuracy of the document. The advantage of this is that the generated file is smaller, the effective information of the image is obtained as much as possible, and the scanning time is short. The user can perform the image processing at a faster speed, but before the output or when needed, the interpolation accuracy in the image processing software is used to improve the accuracy of the document. If the RIP software has anti-aliasing, it is best to turn it on. Example: The 1010cm photo needs to be scanned at 1800dpi and the scanner has a mechanical resolution of 600dpi. At this point, the scan should be performed with an accuracy of 600 dpi, so that the scanned file is much smaller. On this basis, the image processing speed is much faster than the processing of 1800 dpi images. Increase the accuracy of the file before adding text or printing.

To get a better scan, you need higher quality material. The scanning quality of different materials is sorted by color positives, photos, and prints. For color negatives, it is best not for non-professionals because they involve color reproduction. Among them, the print is the most common, and the key to scanning the print is to select the network parameters. The user can first compare the local parameters with different parameters to find the best parameters.

Note: The optical resolution of the scanner refers to the precision of the optics in the scanner. Mechanical resolution refers to the scanner's mechanical movement accuracy, similar to hardware interpolation. Software resolution refers to the resolution a scanner can achieve using an interpolation algorithm.