Đang chuẩn bị liên kết để tải về tài liệu:
Photoshop Lab Color- P9

Photoshop Lab Color- P9: LAB has a reputation for enormous power, yet virtually all reference materials that advocate its use illustrate its capabilities with a single class of image. This chapter introduces the basic LAB correction method and explains why it is so extraordinarily effective. if you happen to have a picture of a canyon. | Figure 11.20 Left the L channel of Figure 11.19. Center the B. Right the composite after blurring the A and B channels. w C examining the LAB channels of the afflicted file. We hope of course that the problem is limited to the A and B in which case we blur and head for the gym. Here though Figure 11.20A indicates that the music is still playing in the L. But because the moiré is blue and yellow it s sharply defined in the B Figure 11.20B. And with ominous foreboding for the fate of the unfortunate moiré please observe that the interference pattern in the B lines up perfectly with that in the L. As usual we work on a duplicate layer preserving the original channels on the bottom. We select the jacket by one means or another the method doesn t affect what comes next. And now we blur the B and to a lesser extent the A until the moiré is gone. That kills the garish yellow and blue but the damage is still visible in Figure 11.20C as it still exists in the L channel temporarily. As we will discover in Chapter 15 blending the A and or B into Figure 11.21 Blending an inverted copy of the original B into the L in Hard Light mode at 100 opacity not only wipes out the moiré but creates a countermoiré left . Right the final version where the blend was reduced to 70 opacity above . 242 Chapter 11 the L is one of those things that in theory sounds as crazy as an intoxicated loon and in practice is maddeningly powerful. The key is to use one of the blending modes in which values of 50 gray are ignored. The usual suspects are Overlay Soft Light and Hard Light. They work in different ways but they all lighten the target wherever they are themselves lighter than 50 darken where darker and do nothing at exactly 50 . And exactly 50 is the midpoint of the A or B a value of zero neutrality. Blend the original B channel that s why we saved the original on its own layer into the L in one of these modes and nothing much will change except for the only area that is significantly off 0B .