The main reason lies in the very principle of scanning in discretization. In addition image details are blurred due to errors in the scanners optics and noise introduced by its electronic path. When slides and photographs are magnified too much their grainy structure begins to appear and this also leads to a loss of sharpness. Printed originals have to deal with moire which also affects the sharpness of the image. Many scanners especially professional ones have builtin hardware modules for sharpening and screen suppression.
These should of course be used during the scanning process e-commerce photo editing they dont take extra time and often work better than the filters included with PhotoShop. Unsharp Mask Filter Pretty much the only way to sharpen after a scan is to apply the Unsharp Mask filter. Its action is based on the peculiarities of the vision of a person who perceives a local increase in contrast at the boundaries of areas with different brightnesses as a subjective increase in sharpness. In other words this filter emphasizes the contours of objects.
Schedule original brightness profile smoothed profile Blur after Unsharp Mask filter In Photoshop this filter is controlled by three options A Amount brightness gain at the border as a percentage of the original value C B by the filter in pixels. Threshold value of the jump in brightness above which the filter starts to act threshold. In advanced scanning programs the number of control parameters is or more. In fact this filter includes not one but two the first stage is the Blur filter. It smoothes the edges by a radius B width.
發表於 2022-10-1 12:54:37
