To activate this feature for a given folder, right-click an empty area of the folder and choose Customize This Folder. Click Next, check Choose or edit an HTML template for this folder. Uncheck the other boxes (if necessary), and click Next once again. If you haven't enabled the Web view for this folder, a prompt will remind you to do so; if you receive the prompt, click OK. Select Image Preview from the Customize list, and click Next and then Finish. To preview any file, just select its icon on the right; you'll see the preview to the left of the list of files.
If you wish, you can increase the preview size: enlarge the Explorer window, close the Folder pane on the left (by clicking the X to the right of the word Folders at the top of the column), or do both. This solution goes only so far: to enlarge the preview area, you have to click the Full Screen Preview button, but this opens a separate window, defeating the convenience of previewing files as you browse the list. If you're willing to roll up your sleeves and edit the folder's template file (folder.htt), you can enlarge the preview area to better use the Web view column.
Here's how to edit the folder's template file. As before, right-click an empty area of a folder that contains your images, and choose Customize This Folder. Click Next, make sure Choose or edit an HTML template for this folder is checked, uncheck the other boxes (if necessary), and click Next again. Select Image Preview from the list, but this time also check I want to edit this template. Click Next to see the folder.htt file open in Notepad. The HTML code may look scary, but you'll be making only a few changes.
First, find the line that begins with #ThumbDiv (it should be visible without any scrolling). In that line change "top: 50%" to "top: 5%". Then change "height: 50%" to "height: 95%". The preview will now use most of the height in the Web view column. Next, choose Edit-Replace. Type 300 in the "Find what" box and 500 in the "Replace with" box. Click Find Next. Make sure the 300 this search finds is part of an expression line containing "panelwidth > 300" or "panelwidth = 300". Click Replace twice (there should be only two occurrences in the file). Click OK, and then click Cancel to close the Replace dialogue box. This change allows the preview area to keep expanding as you increase the size of the Explorer windows - especially helpful if you use a high-resolution display.
The changes you've made so far will enlarge the preview area, covering the file information that normally appears in the Web view column. This isn't a concern, since you can see most of that information in the file list by choosing View-Details. However, the Web view column gives some information not available in the file list's Detail view, like the dimension of the image in pixels. To make the image dimensions readily visible, you can move the image information to the top of the column so the preview image won't cover it. Choose Edit-Find, then type and click Find Next. When Explorer finds the text, click Cancel to close the Find dialogue box. Now press
Now when you open the folder and select a file on the right, the preview area will occupy most of the Web view column and show the image dimensions above the preview. If you don't get the results you want, right-click an empty area in the folder and choose Customize This Folder. Click Next, select Remove customizations, click Next, make sure Restore default folder template is checked, click Next, and click Finish. Then try again.