Adobe Photoshop CS5 for Photographers - Martin Evening [310]
Figure 14.12 The Save for Web interface showing the GIF settings.
The Diffusion dithering algorithm is effective at creating the impression of greater color depth and reducing any image banding, and the Dither slider allows you to control the amount of Diffusion dithering (the ‘Pattern’ and ‘Noise’ options have no dither control). If the image to be saved has a transparent background, the ‘Transparency’ option can be kept checked in order to preserve the image transparency in the saved GIF. To introduce transparency in an image you can select the color to make transparent using the eyedropper tool and then click inside the image preview area. The color chosen will appear selected in the color table. Select one or more colors and click on the Map Selected Colors to Transparent button in the Color Table (see Figure 14.13). You can then apply a diffusion, pattern or noise dither to the transparent areas, which can help create a smoother transparent blend in your GIF images.
Figure 14.13 This shows a close-up of the color table showing the Color palette options menu. A: Maps the selected color to transparency. B: Shifts/unshifts selected colors to the Web palette. C: Locks the color to the palette to avoid deletion. D: Adds an eyedropper-selected color to the palette
The ‘Lossy’ option allows you to reduce the GIF file size by introducing file compression. This can be helpful if you have an overlarge GIF file, but applying too much compression will noticeably degrade the image until it looks like a badly tuned TV screen. The ‘Interlaced’ option can make the image appear to download progressively in strips, but adds slightly to the file size.
Zoomify™ Export
The ‘Zoomify™ Export’ option in the File menu allows you to create an output folder containing all the necessary components to produce zoomable image web pages (Figure 14.14). Visitors are then able to view the pages created with the Zoomify export plug-in so long as they have an up-to-date Flash plug-in for their browser. Zoomify pages are ideal for portfolio presentations and commerce websites, where customers can easily view large images in close-up. If you go to the Zoomify website at www.zoomify.com, you can see some examples of customer sites where the Zoomify Export plug-in has been used.
Figure 14.14 Here is the Zoomify™ Export dialog box, showing the typical settings that might be used to create a zoomable image. When you click OK this creates a folder containing all the necessary components to display a zoomable image on the Web. Once created, all you have to do is upload the folder to your website and add the /foldername/basefilename.htm/ to the usual URL weblink (note that the base file name referred to here is based on the image's file name). Visitors to such pages can left mouse-click on an area of interest to zoom in and -click to zoom out. You can mouse down and drag to scroll, or use the navigator preview to select an area of interest to scroll to. There are no usage fees or restrictions on the usage of this plug-in. As is mentioned on the Zoomify website: ‘We simply ask you not to decompile the Zoomify Viewer SWF file, not to redistribute the Zoomify Viewer source code (available in the Zoomify Flash product), and not redistribute the Zoomify Converter. Your content is yours, and redistributing the Zoomify Viewer swf is encouraged.’
Chapter 15. Automating Photoshop
Getting to know the basics of Photoshop takes a few months, although it will take a little longer than that to become a fluent Photoshop user. One way you can speed up your Photoshop work is by learning how to use many of the various keyboard shortcuts. There are a lot of these in Photoshop, so it is best to learn a few at a time, rather than try to absorb everything at once.