This section tells about transforming user-selected images before upload. Image Uploader can resize, recompress, rotate, crop and watermark images on a client side. These transformations may be combined, for example, an image can be resized and watermarked at the same time. You can create any number of transformed versions of one image, for instance, the first one is a considerably downsized version, the second is watermarked, and the third is cropped and watermarked. An image you get after applying any set of transformations is called thumbnail.

To configure a thumbnail you should add a Converter to the Uploader.Converters collection and set its Mode property to Thumbnail. For more information about converters, please, see the Configuring Files to be Uploaded topic.

Each thumbnail is a file, so on the server you can save uploaded thumbnails using any approach examined in the saving uploaded files topic.

Now, when you have an idea about what thumbnail means in terms of Image Uploader, how to configure converters, and how to save uploaded files, let us briefly describe each topic of this section:

  • The Resizing and Recompressing topic tells about basic concepts, such as thumbnail size, quality, and resolution. It also gives an advice on handling the situation when a thumbnail cannot be created.
  • The Rotating and Cropping topic describes how to rotate and crop images in two modes: manual and automatic. It also provides instructions on highlighting a rectangular area of an image to mark an object or a person out.
  • The Applying Watermarks topic contains a lot of information about adding watermarks, which can be text or image, solid or transparent, and can be put in any place of an image.
  • The Working with EXIF and IPTC Metadata topic gives a brief definition of what metadata are, and describes Image Uploader possibilities in metadata handling, especially preserving metadata in thumbnails.
Note

Image Uploader can load a lot of image formats and display previews for them, however, it can save the image only into the single format - JPEG. So, all thumbnails created by Image Uploader are JPEG images.