Picasa allows you to resize images by exporting them to a folder or as a html page. Usually, Picasa only lets you define a maximum size which is used for the height or width depending on which is larger. More control of the exported image size can be gained through the Export as Html Page template system.
Defining separate limits for image height and width
Picasa's Export as Html Page template system allows you to override the limits for the maximum pixel size of images set on the Export as Html Page screen. To override the settings you must manually edit the template's index.tpl file with a text editor, like Notepad, each time you want to change the limits for the exported images. The index.tpl file can be found in the individual template's folder where templates are installed by Picasa.
C:\Program Files (x86)\Google\Picasa3\web\templates (on 64-bit systems)
C:\Program Files\Google\Picasa3\web\templates (on 32-bit systems)
The index.tpl file uses the pound sign (#) as a comment character. Anything on the current line after the pound sign is ignored.
The index.tpl file defines two variables for the height and width of the exported images.
define imageWidth 800
define imageHeight 600
Here imageWidth defines a maximum width of 800 pixels for the exported images and imageHeight defines a maximum height of 600 pixels. Picasa will resize the images to whichever limit is hit first keeping the original size ratio of the image being resized. Picasa does not enlarge images. If the image is smaller than the limits set in the index.tpl file, the image will remain its original size.
Limits in one direction only can be defined by setting one limit to the desired size and the other to a size greater than any image size possible.
define imageWidth 200
define imageHeight 10000
This will result in all images being exported at 200 pixels wide unless the original width is less than 200 pixels.
Two sets of images
Picasa's Export as Html Page always exports two sets of images to two separate folders. Images sent to the images folder are controlled by the imageWidth and the imageHeight variables. Images sent to the thumbnails folder are controlled by the thumbnailWidth and the thumbnailHeight variables. Each set of images are independent and can be radically different sizes. If only one set of images is needed, the thumbnailWidth and the thumbnailHeight variables can be set to small sizes to minimize processing time.
Adding shadows to images
Picasa's Export as Html Page can add a shadow effect to images by defining a value of "1" for the variables that control them. A value of "0" turns off the addition of shadows. Shadows add 10 pixels to the defined height and width of the image.
Shadows for images sent to the images folder are controlled by shadowedImages which if not defined will default to "0" and no shadows will be added. Shadows for the images sent to the thumbnails folder are controlled by shadowedThumbnails which defaults to "1" if not defined and shadows will be added.
More information
More information on Picasa's Export as Html Page template system can be found in the documentation folder located in the same folder as the templates folder. You can also find some useful information by reading the index.tpl files in some of the default templates that come with Picasa.
Download my template
If you would like to download the template I use it can be found here. It is currently set to export images with a maximum width of 400 pixels and a maximum height of 300 pixels. After export, most of this page will be displayed in your default browser.
Unzip the file and copy or move the "Custom Image Resizing" folder to the folder that contains Picasa templates. On Windows systems that folder can be found at :
C:\Program Files (x86)\Google\Picasa3\web\templates (on 64-bit systems)
C:\Program Files\Google\Picasa3\web\templates (on 32-bit systems)
