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Uploading Images for Thumnails
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1. Be sure you have PHP 4.3 with GD-library installed on your server. PHP 5 is better.
2. Start from a fresh copy and upload the theme at wp-content/themes/premium/. Do not change ‘premium’ to anything because it will break everything.
3. Make the folder “scripts” and “cache” writable (777 or 755). Try 777 first. These folder are located in wp-content/themes/premium/ and wp-content/themes/premium/scripts/. You can do this using FTP or any online file manager from you web hosting company.
4. Add a custom field in the post. The custom field key MUST be 'Image' (letter cases are important).
5. Fill the custom field value with the path of your image. It MUST start with 'wp-content'. If you have the image located at 404- not found then the key value of the custom field MUST be wp-content/uploads/2008/06/file_name.jpg (Notice there is no
yourblog.com in the value)
6. You could skip number 4 and 5 if you choose the First-Image automatic generation. To have your thumbnail generated, simply add images in your post and the first-images will be used as thumbnails.
7. Read this:
Tutorial: TimThumb Thumbnail Generation with Arthemia Theme - Jubel and The Unessential if you want to use Post Custom Field.
8. The script currently only support JPG images.