Reply To: How Do I Change the Size of the Optimal Header Image?

First you’ll need to go into your functions file and change the header height size from 100 to 140.  The code will look like this –

/** Add support for custom header */
add_theme_support( 'genesis-custom-header', array( 'width' => 960, 'height' => 100 ) );

Then you can upload your image using the WP Header uploader. Make sure it has the same dimensions as the functions file.

You may also need to make adjustments to your css as well. It looks like you already know how to do this, if not just let me know.