Archive for May, 2011
In an earlier post on Object Export Options, I had shown you how to specify Alt-text. In this post, we’ll see how Object Export options help us in the EPUB and HTML workflows. You can use the Object Export options to create different conversion settings on each object, with special attention spent on settings useful for different screens sizes and pixel densities (ppi).
Unlike alt text, which is supported in all three major export formats—PDF, EPUB, and HTML— the EPUB and HTML tab in the Object Export dialog box represents conversion and formatting options unique to EPUB and HTML.
The main purpose for this tab is to set image conversion properties on an object by object basis. This enables you to apply different degrees of quality on each individual object. If not specified, the global conversion options defined by EPUB or HTML export is used. To enable per object conversion settings, the “Custom Rasterization” box must first be checked.
Below is a description for the major features. (The rest are easy to understand).
You can choose between fixed size or the new relative to page width size. Using Fixed results in an image with static height and width pixel dimensions based on the size of the object used in the InDesign document. “Relative to page width” setting sets a % value based on the width of the image relative to the InDesign page width. The % value enables the image to resize automatically based on the screen size of the device or the size of the browser window. “Relative” is recommended when producing EPUBs that are intended to be viewed on different devices.
PNG is now supported, in addition to GIF and JPEG. PNG is a lossless format and also supports transparency. When PNG is selected, compression options are dimmed out.
While operating systems have standardized on either 72 or 96 ppi, mobile devices range from 132 ppi (iPad), to 172 ppi (Sony Reader), to over 300 ppi (iPhone 4). New in CS5.5 is the ability to specific a ppi value for each object selected. Values include 72, 96, 150 (average of all ebook devices today), and 300.
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Object Export options consolidate two major functions when exporting images to EPUB/HTML and Tagged PDF.
- The first function is the requirement to add and persist “alternative text” to placed images and graphics, which i’ll talk about in this post.
- The second function is the ability to create different conversion settings on each object, with special attention spent on settings useful for different screens sizes and pixel densities (ppi).
The dialog box has been made modeless, so that you can select different individual frames while leaving the dialog active.
The Object Export Options can be applied to both graphic and text frames, as well as to groups. You can also apply conversion options to text frames, which is very useful when you want to control the quality of rasterization applied to text effects like Drop Shadows, and Bevel and Emboss, in the exported HTML and EPUB files.
Object Export Options > Alt Text
Alternative text (or alt text for short) is a brief text based description of the subject captured in the photograph or illustration. Adding alt text is a common practice when creating HTML web pages and is also supported in EPUB and Tagged PDF. You can find information on writing Alt text at http://www.w3.org/QA/Tips/altAttribute. In InDesign CS5, do the following:
- Select an object and choose Object > Object Export Options > Alt Text.
- Choose one of the following
- From Structure: For legacy INDD files where users have already created all of the alt-text using the Structure Pane.
- From XMP (Title | Description | Headline ): Common XMP metadata fields used to capture some text about the image or graphic. If the XMP data is updated in another application like Adobe Bridge, updating the link in InDesign results in the alt text string being updated.
- From Other XMP: Only to be used by an XMP expert! Requires understanding the XMP path namespace and the array value. For example, the Bridge user interface supports IPTC Core, which contains a field titled “IPTC Subject Code”. If this was the field where Alt text string is stored, then in InDesign CS5.5, the value would have to be written as “Iptc4xmpCore:SubjectCode”. For advertuous mortals, in Photoshop, you can view the full namespace in an image under File Info > Raw Data.
- Custom: Users can enter their own custom alt text string. Useful when there is no pre-existing data, or when the metadata text is lacking in quality.
Besides this there are a few otherways Alt Text can be created in InDesign:
- From Microsoft Word: When you import a Word document with graphic images that have Alt Text already created in Word, these are converted to native InDesign alt text. Currently, only the Windows version of Word supports this feature.
- When a text frame has Object Export Settings for EPUB/HTML conversion to a graphic format like PNG, GIF, or JPEG, any alt text value is appropriately be passed through.
James Wamser goes over the common issues that arise when preparing InDesign documents for printing and shows how to tweak PDF and document settings to ensure the perfect print.
InDesign CS5: Print Production Guidelines from Lynda.com shows how to avoid mistakes by preparing documents correctly upfront, covering document construction, layout, ink management settings, and output options. Prepress processes in Acrobat are also covered, including accurate soft proofing and packaging in the PDF/X formats. Exercise files accompany the course.