Đây là Giảm lọc tiếng ồn được sử dụng để giúp loại bỏ tiếng ồn từ một nắm bắt kỹ thuật số được chụp tại ISO 1250, nơi mà các bộ lọc giảm tiếng ồn giúp loại bỏ hầu hết những đồ tạo tác tiếng ồn. Cách dễ nhất để tôi chứng minh sức mạnh của biến đổi Warp là để có một lớp lá cờ làm-up | Martin Evening Adobe Photoshop CS4 for Photographers Replacing film grain You may encounter a problem if the photographic original contains noticeable film grain since even with the selective application of the Dust Scratches filter you may end up with some softening where you retouch the image. To counteract this it may help to apply a small amount of noise after you have applied the Dust Scratches filter. Add enough noise to match the grain of the original usually around 2-3 . This will enable you to better disguise the history brush retouching. Alternative history brush spotting technique This spotting method has evolved from a technique that was first described by Russell Brown Senior Creative Director of the Adobe Photoshop team. It revolves around using the Remove Dust Scratches filter which is found in the Filter o Noise submenu. If this filter is applied globally to the whole image you can easily end up with a very soft-looking result. So ideally this filter should be applied selectively to the damaged portions of a picture. The technique shown here has the advantage of applying the filtered information via the history brush such that only the pixels which are considered too dark are painted out. This modified approach to working with the Dust Scratches filter avoids destroying the tonal values in the rest of the picture. As you can see the technique works well when you have a picture that is very badly damaged and where using the clone stamp would be a very tedious process. What is really clever is the way that the Lighten and Darken blend modes can be used to target which pixels are repaired from the stored Dust Scratches history state. 1 This scanned photograph serves as a good example with which to demonstrate the history brush spotting technique as there are a lot of dust marks clearly visible in the enlarged detail views shown in this picture. 400 Chapter 8 Image retouching tXiSt A Scratches s IOC c J Cancel t M Preview Radius. pixels .
