Images form an integral part of a website by providing additional context for the site visitors. Although a wide variety of graphic file formats exist, GIF, JPEG, and PNG file formats are commonly used in web pages. GIF and JPEG file formats are compatible with web pages, and can be viewed in most browsers. The following text gives more information about these file formats:
GIF (Graphic Interchange Format) - GIF files use a maximum of 256 colors, and are best for displaying noncontinuous-tone images. GIF files are ideal for displaying large areas of flat colors, such as navigation bars, buttons, icons, logos, or other images with uniform colors and tones.
JPEG (Joint Photographic Experts Group) - The JPEG file format is the superior format for photographic or continuous-tone images, because JPEG files can contain millions of colors. As the quality of a JPEG file increases, so does the file size and the file download time. You can strike a good balance between the quality of the image and the file size by compressing a JPEG file.
PNG (Portable Network Group) - The PNG file format is a patent-free replacement for GIFs that includes support for indexed-color, grayscale, true-color images, and alpha channel support for transparency. PNG files retain the original layer, vector, color, and effects information such as drop shadows. Further, all the elements are fully editable always. Files must have the .png filename extension to be recognized as PNG files by Dreamweaver.
Dreamweaver is not a WYSIWYG (What you see is what you get) editor. That is, you can add or insert images using Dreamweaver, but you cannot move or position the images using the interface.
To move your images in your layout, you must use CSS that displays your HTML content the way you want. You can refer to the basic tutorials on HTML and CSS to learn how to work with images using code. You can also view the tutorial on working with images in Dreamweaver.
To know how to insert and use images using the Dreamweaver application, see the following sections.
When you insert an image into a Dreamweaver document, a reference to the image file is generated in the HTML source code. To ensure that this reference is correct, the image file must be in the current site. If the image is not in the current site, Dreamweaver asks whether you want to copy the file into the site.
Dreamweaver also allows you to insert images dynamically. Dynamic images are those images that change often. For example, advertising banner rotation systems that randomly select a single banner from a list of potential banners. The system dynamically displays the selected banner’s image when a page is requested.
You can also drag-and-drop any layer from the Extract panel to any place in Dreamweaver Live View using Live Guides and Element Quick View. The Extract Panel allows you to upload PSD files and then drag-and-drop any layer in the PSD file directly into your Dreamweaver document.
After you insert an image, you can set the image tag and accessibility attributes that screen readers pick up for visually impaired users. You can edit these attributes in HTML code.
For information on extracting images from your PSD compositions, see Extract images from PSD files.
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Place the insertion point where you want the image to appear in the Document window and do one of the following:
- In the Insert panel, select HTML from the drop-down list. Click Image. Double-click or drag the icon to the document window (or to the Code view window if you are working using code).
- Drag an image from the Assets panel (Window > Assets) to the desired location in the Document window; then skip to step 3.
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If you are working in an unsaved document, Dreamweaver generates a file:// reference to the image file. When you save the document anywhere in the site, Dreamweaver converts the reference to a document-relative path.
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When you insert images, you can use an absolute path to an image that resides on a remote server. That is, an image that is not available on the local hard drive. However, if you experience performance issues while working, you can disable viewing the image in Design view by deselecting Commands > Display External Files.
The Images Property inspector allows you to set properties for an image. If you do not see all of the image properties, click the expander arrow in the lower-right corner.
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W and H
The width and height of the image, in pixels. Dreamweaver automatically updates these text boxes with the image’s original dimensions when you insert an image in a page.
If you set W and H values that do not correspond to the actual width and height of the image, the image is not displayed properly in a browser. To restore the original values, click the W and H text box labels, or the Reset image size button that appears to the right of the W and H text boxes.
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You can change these values to scale the display size of this image instance. However, the change does not reduce download time, because the browser downloads all the image data before scaling the image. To reduce the download time, and to ensure that all the instances of an image appear at the same size, use an image-editing application to scale images.
Src
Specifies the source file for the image. Click the folder icon to browse to the source file, or type the path.
Link
Specifies a hyperlink for the image. Drag the Point-To-File icon to a file in the Files panel. Click the folder icon to browse to a document on your site, or manually type the URL.
Alt
Specifies alternative text that appears in place of the image for text-only browsers or for browsers that have been set to download images manually. For visually impaired users who use speech synthesizers with text-only browsers, the text is spoken out loud. In some browsers, this text also appears when the pointer is over the image.
Target Specifies the frame or window in which the linked page loads. This option is not available when the image is not linked to another file. The names of all the frames in the current frameset appear in the Target list. You can also choose from the following reserved target names:
- _blank loads the linked file into a new, unnamed browser window.
- _new loads the linked file into a new browser window.
- _parent loads the linked file into the parent frameset or window of the frame that contains the link. If the frame containing the link is not nested, the linked file loads into the full browser window.
- _self loads the linked file into the same frame or window as the link. This target is the default target. You do not need to specify this value explicitly.
- _top loads the linked file into the full browser window, thereby removing all frames.
Edit
Starts the image editor you specified in External Editors preferences and opens the selected image.
Update from original
When the image on the Dreamweaver page is out of sync with the original Photoshop file, Dreamweaver detects that the original file has been updated. The application displays one of the Smart Object icon’s arrows in red. When you select the web image in Design view and click the Update from Original button in the Property Inspector, the image updates automatically. The updated image reflects the changes that you made to the original Photoshop file.
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You can also edit image attributes in Live View using the Quick Property Inspector.
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Do one of the following to enter a name or a brief description for the image in less than 50 characters in to the Alternate Text box. The screen reader reads the information you enter here.
- Edit image attributes in Live View using the Quick Property Inspector.
You can visually resize elements such as images, plug‑ins, Shockwave or SWF files, applets, and ActiveX controls in Dreamweaver.
Visually resizing an image helps you see how the image affects the layout at different dimensions but it does not scale the image file to the proportions that you specify. If you visually resize an image in Dreamweaver without using an image-editing application, the user’s browser scales the image when the page is loaded. It might cause a delay in page download time and the image is not displayed properly in the user’s browser.
To reduce download time and to ensure that all instances of an image appear at the same size, use an image-editing application to scale images. Read the following procedure to know how to visually resize an element.
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- To adjust the width and the height of the element at the same time, drag the corner selection handle.
- To preserve the element’s proportions (its width-to-height ratio) as you adjust its dimensions, Shift-drag the corner selection handle.
- To adjust the width and height of an element to a specific size (for example, 1 x 1 pixel), use the Property Inspector. Enter a numeric value in the W and H fields. You can visually resize elements to a minimum of 8 x 8 pixels.
Adjust the width and height of an element using the Property Inspector
When you resize an image in Dreamweaver, you can also resample the image to accommodate new dimensions. Resampling adds or subtracts pixels from a resized JPEG and GIF image files to match the appearance of the original image as closely as possible. Resampling an image reduces its file size and improves download performance.
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Resize the image as described in the section Resize an image.
Dreamweaver provides basic image-editing features that let you modify images without having to use an external image-editing application such as Photoshop. The Dreamweaver image-editing tools are designed to let you easily work with content designers responsible for creating image files for use on your website.
You can resample, crop, optimize, and sharpen images in Dreamweaver. You can also adjust the brightness and contrast of images.
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You do not need to have Photoshop or other image-editing applications installed on your computer to use the Dreamweaver image-editing features.
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Optimize
Select a preset, specify a file format, and specify the level of quality. As you move the slider across the quality levels, you can see the file size of the image in the dialog box. Click OK once done.
Resample
Adds or subtracts pixels from a resized JPEG and GIF image files to match the appearance of the original image as closely as possible. Resampling an image reduces its file size and improves download performance.
When you resize an image in Dreamweaver, you can resample it to accommodate its new dimensions. When a bitmap object is resampled, pixels are added to or removed from the image to make it larger or smaller. Resampling an image to a higher resolution typically causes little loss of quality. Resampling to a lower resolution, however, always causes data loss and usually a drop in quality.
Crop
Edit images by reducing the area of the image. You can use crop to place more emphasis on the subject of the image, and remove unwanted aspects surrounding the center of interest.
Brightness and Contrast
Modifies the contrast or brightness of pixels in an image. Brightness and Contrast affects the highlights, shadows, and midtones of an image. You typically use Brightness/Contrast when correcting images that are too dark or too light.
Sharpen
Adjusts the focus of an image by increasing the contrast of edges found within the image. When you scan an image, or take a digital photo, the default action of most image capturing software is to soften the edges of the objects in the image. The scanning prevents extremely fine details from becoming lost in the pixels from which digital images are composed. However, to bring out the details in digital image files, it is often necessary to sharpen the image. Using the Sharpen option increases the edge contrast, making the image appear sharper.
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Dreamweaver image-editing features apply only to JPEG, GIF, and PNG image file formats. Other bitmap image file formats cannot be edited using these image-editing features.
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When you crop an image, the source image file is changed on disk. It is recommended that you keep a backup copy of the image file if you have to revert to the original image.
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Preview the image and ensure that it meets your expectations. If not, select Edit > Undo Crop to revert to the original image.
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You can undo the effect of the Crop command and revert to the original image file until you quit Dreamweaver, or edit the file using an external image-editing application.
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the image Property inspector.
Sharpening increases the contrast of pixels around the edges of objects to increase the image’s definition or sharpness.
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To specify the degree of sharpening Dreamweaver applies to the image, drag the slider control. You can also enter a value between from 0 through 10 in the text box. As you adjust the sharpness of the image using the Sharpen dialog box, you can preview the change to the image.
Sharpen images in Dreamweaver -
Save your changes by selecting File > Save, or revert to the original image by selecting Edit > Undo Sharpen.
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You can only undo the effect of the Sharpen command and revert to the original image file before you save the page containing the image. After you save the page, the changes made to the image are permanent.
Brightness and Contrast option modifies the contrast or brightness of pixels in an image. This option affects the highlights, shadows, and midtones of an image. You typically use Brightness and Contrast when correcting images that are too dark or too light.
A rollover is an image that, when viewed in a browser, changes when the pointer moves across it. You must have two images to create the rollover. A primary image or the image displayed when the page first loads, and a secondary image or the image that appears when the pointer moves over the primary image. Both the images in a rollover must be of the same size. If the images are not the same size, Dreamweaver resizes the second image to match the properties of the first image.
Rollover images are automatically set to respond to the onMouseOver event. You can set an image to respond to a different event. For example, a mouse click or change a rollover image.
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In the Insert Rollover Image dialog box, select the images and set the properties for the rollover. You can set the following properties:
Setting properties of a rollover image
Original image
The image you want to display when the page loads. Enter the path in the text box, or click Browse and select the image.
Rollover Image
The image you want to display when the pointer rolls over the original image. Enter the path or click Browse to select the image.
Preload Rollover Image
Preloads the images in the browser’s cache so no delay occurs when the user rolls the pointer over the image.
When clicked, Go to URL
The file that you want to open when a user clicks the rollover image. Enter the path or click Browse and select the file.
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If you do not set a link for the image, Dreamweaver inserts a null link (#) in the HTML source code to which the rollover behavior is attached. If you remove the null link, the rollover image does not work.
While in Dreamweaver, you can open a selected image in an external image editor. When you return to Dreamweaver after saving the edited image file, any changes you made to the image are visible in the Document window.
You can set up a primary external editor and also set which file types an editor opens. You can select multiple image editors. For example, you can set preferences to start Photoshop when you want to edit a JPEG file and start a different image editor when you want to edit an animated GIF.
You can select an image editor for opening and editing graphic files. To select an external image editor, perform the following steps:
You can apply any available behavior to an image or an image hotspot. When you apply a behavior to a hotspot, Dreamweaver inserts the HTML source code into the area tag. Three behaviors apply specifically to images: Preload Images, Swap Image, and Swap Image Restore.
Preload Images
Loads images that do not appear on the page right away such as images that are swapped in with behaviors, AP elements, or JavaScript, into the browser cache. Preloading images prevents delays caused by downloading when it is time for the images to appear.
Swap Image
Swaps one image for another by changing the src attribute of the img tag. Use this action to create button rollovers and other image effects (including swapping more than one image at a time).
Swap Image Restore
Restores the last set of swapped images to their previous source files. This action is automatically added whenever you attach the Swap Image action to an object by default. In this case, you need not select the Swap option manually.
You can also use behaviors to create more sophisticated navigation systems, such as jump menus.
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