Adobe Photoshop CS5 for Photographers - Martin Evening [183]
Manual tone mapping
There is yet another way to tone map an HDR image. You can add adjustment layers to a 32-bit image and use these to edit the tone and color. Previously, the ability to paint and add layers was only available in the extended versions of the program, but this is something that you can now do in all versions of Photoshop CS5. In Figure 7.7, you can see a preview of an image that was in 32-bit per channel mode, where I used a combination of Exposure adjustment layers to adjust the contrast and brightness and Levels adjustment layers to adjust the color, and masked each of these individual adjustment layers to selectively apply these adjustments to specific areas of the image. By building up a succession of adjustment layers, I was able to tone map the original HDR image just the way I wanted, but without having to render it as an LDR version just yet. If you wish to preserve all the layers when saving such a file, you will need to use the Photoshop, TIFF, Portable Bit Map or PSB format. Preserving the layers means that the master image file size will be increased, but direct HDR image editing does offer a lot of flexibility.
Figure 7.7 You can use adjustment layers to manually tone map the 32-bit data while keeping the HDR image in it's original 32-bit mode.
Exposure adjustments
Although you can use the Exposure adjustment to edit 16-bit or 8-bit images, it is really designed as an image adjustment for working on 32-bit images.
Work from the top downwards
When you add a new adjustment layer, it is best to add the newest layer at the bottom of the layer stack just above the Background layer. This reduces the length of time you'll see the ‘Building histograms’ dialog appear on the screen.
Chapter 8. Image Retouching
Photoshop has become so successful that it's very name is synonymous with digital image retouching. Photoshop retouching tools such as the humble clone stamp have been around since the very early versions of the program and been used and abused in equal measure. The new retouching tools that have been added since then mean that you can now transform images almost any way you want. As my colleague Jeff Schewe likes to say, ‘you know why Photoshop is so successful? Because reality sucks!’ Well, that's Jeff's viewpoint, but then he does come from a background in advertising photography where heavy retouching is par for the course. The techniques described in this chapter will teach you some of the basic techniques, such as how to remove dust spots and repair sections of an image. We'll then go on to explore some of the more advanced techniques that can be used to clean up and enhance your photographs.
Basic cloning methods
The clone stamp tool and healing brush are the most useful tools to use at the beginning of any retouching session. You can use these to carry out most basic retouching tasks before you proceed to carry out the more advanced retouching steps.
Clone stamp tool
To use the clone stamp tool, hold down and click to select a source point to clone from. Release the key and move the cursor over to the point that you wish to clone to, and click or drag with the mouse. If you have the tool set to aligned mode, this establishes a fixed relationship between the source and destination points. If the clone stamp is set to the non-aligned mode, the source point remains the same and the clone stamp will keep sampling from the same spot until you -click again to establish a new source point. When working with the clone stamp or healing brush I do find it helps to use a graphics tablet like the Wacom™ device (shown in Figure 8.1). This can help you work more quickly and efficiently.
Figure 8.1 If you are carrying out any type of retouching work which relies on the use of the paint tools, a pressure sensitive graphics tablet and pen, such as the