Image server
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 | This article possibly contains original research. (November 2009) |
An image server is web server software which specializes in delivering (and often modifying) images.
While traditional web servers generally supply clients with static copies of image files, image servers usually perform additional image processing before serving the file. These functions may include frame/format selection, resizing, cropping, alpha blending, compositing source images, rotating, and color adjustment, and filtering.
Uses
The proliferation of mobile devices, screen resolutions, and pixel densities has forced web designers to create an ever-increasing number of image variations. Image servers capable of dynamic image resizing can produce the required sizes and variations on demand, eliminating repetitive work and the room for human error.
Zoomable photos are a cornerstone of e-commerce, and may be the most popular use for image servers.
In e-commerce, image servers are qualified by their abilities to scale to hundreds of thousands of images, to multiple CPUs or load-balanced server machines, and to the quantity and quality of their image processing functionalities, such as resizing, compositing, zoom and 3D viewers, and the addition of dynamic data to the images in the form of overlaid text or graphics.
Dynamic compositing is also extremely useful for merchants who permit product customization. Many vehicle manufacturers use dynamic compositing to let the visitor visualize their customizations.
Large image sets, mapping, and geospatial use
Geospatial or mapping has particular need for specialized "image servers". Aerial and satellite images are georeferenced and can be hundreds or thousands of gigabytes in size. Traditional mechanisms for serving this data have proved inadequate. The first specialized image server for geospatial image data was Image Web Server, released in 1999. Image Web Server, among other protocols, supports ECWP (ERDAS Compressed Wavelet Protocol) that "streams" large images to a user's application, rather than sending a regular image over HTTP. The well known standard for a distributed architecture of geospatial data is Web Map Service.
Responsive web design & mobile support
One problem that plagues web masters is that for their site to be compatible with as many web browsers as possible, they have to use very general images to fit all. An image with a width of 400 pixels will take up half of the screen in an 800×600 resolution, but in a 1280×1024 resolution it will only cover a third. Therefore, if the page is designed for 800×600 resolution it will look considerably worse in 1280×1024. An image server can solve that by dynamically adjusting the size of the image according to the user's browser settings. Similarly, old versions of Internet Explorer have trouble displaying PNG and MNG images, but an image server could detect the user's browser version and send the image in a supported format such as GIF instead.
= Other specialized uses
Other more specialized image servers can add value to existing systems by providing services like automatic object recognition, copyright detection and image querying by visual similarity.
Standards and Specifications
Image servers which offer open APIs and have standardized client applications are aften more attractive.
- RESTful Image API (RIAPI) - 2012 - Draft specification for a simple, declarative, querystring-based image API. Browser-compatible.
- Internet Imaging Protocol (IIP) - 1997 - (optionally) HTTP-based imperative protocol for image editing; heavily tied to the FlashPix file format.
- International Imaging Industry Association
- ECWP (ERDAS Compressed Wavelet Protocol)
- Web Map Service
Imaging Server Software
Open Source imaging server
- IIPImage - for high resolution TIFF and JPEG2000 images
- Apophnia - Open Source imaging server, supporting various types of transformations
- Djatoka - Open Source imaging server, Java-based
- ImageResizing.Net - High-performance open-source imaging server with 38 plugins. Supports Amazon Web Services, MS SQL, CloudFront, and seam carving.
Commercial Image Server
- Picaris Platform, Dynamic rendering and compositing server for product images
- Bildero Server, Dynamic Imaging with one source Images, 360 spin, Zoom and Pan, resize images on the fly
- LiquidPixels LiquiFire, Dynamic Imaging appliances for Zoom and Pan, 360 spin, colorization, text rendering, device transcoding
- NeptuneLabs FSI Server, Realtime for 2D, 3D (stereoscopic), 360 spin, page flip, image manipulation