About XDepth
Although providing augmented precision and a wider color gamut, XDepth can be built on top of most existing image compression technologies and algorithms, thus making XDepth fully compatible with the base algorithm of choice.
High Dynamic Range
High Dynamic Range (HDR) is a technology that provides high-contrast digital imaging and video. While DeepColor and the xvYCC color space are intended to enhance the number of shades within a given black and white point, HDR enables pixels to assume values beyond the "white point", thus allowing extreme pixel contrast and digital dynamic exposure.
HDR images are typically represented using 32bit/channel, e.g. 96bit/pixel, thus HDR files are 4 times larger than common 24bit/pixel (Low Dynamic Range or LDR) uncompressed images.
XDepth allows lossy compression of HDR images with compression ratios similar to those achieved by the Jpeg algorithm.
HDR is currently employed among professional and amateur photographers, 3D-animation and visual-FX studios since it provides greater realism when dealing with exposure, brightness/contrast and color adjustments, post-processing and artistic effects.
Other external references:
HDRI on Wikipedia
Paul Debevec's HDR Recovering
Greg Ward's HDR Encodings
XDepth Comparision
The following test shows XDepth HDR capabilities for low-quality settings on a simple, synthetic HDR image. Click on the image below to view results:
XDepth HDR Features
XDepth is fully compatible with Jpeg files.
In fact you will be able to open .xdp files in any application that supports Jpeg.
You can also rename your .xdp files as .jpg and they will still open as HDR in Photoshop.
XDepth images can be viewed on any browser without having to convert them to Jpeg or other web-compatible formats.
If named with a ".jpg" extension, XDepth images can be previewed as thumbnails and opened in any Operating System, image editing and image viewing software.
Applications that explicitly support XDepth - as a plugin or as a built-in reader - will be able to open XDepth files in HDR mode thus retrieving the full compressed HDR image.
Compression
XDepth allows great quality and very small file-size.
With some synthetic HDR images the XDepth compressed file is 12 times smaller than its HD Photo counterpart and 173 times smaller than the uncompressed HDR image.
XDepth performance is dependant on the base algorithm. The basic version of XDepth is based on the popular Jpeg-1 algorithm, thus offering similar quality and compression ratios.
Lossless options in the XDepth format benefit of a notable advantage from the internal representation of the image, resulting in higher compression ratios while keeping 100% of the data, bit-wise.
Quality
HDR images are very difficult to compress. Other technologies drop much of the details in darker areas proportionally to the increased contrast.
XDepth maintains the same perceived quality throughout the whole image, regardless of the contrast.
XDepth offers a variable bit-depth throughout each HDR image thus providing extra precision only where it's required.
Spatial resolution instead is always dependant on the base algorithm. In the basic version of XDepth spatial resolution is constant, while other technologies will drop spatial resolution in order to account for the extra space required by HDR data and often failing in keeping file-size reasonably small.
Future
Future implementations of the XDepth technology will support 48bit/pixel images always maintaining full compatibility with Jpeg.
The 48bits/pixel technology also incorporates a very efficient built-in deblocking feature.
Increased precision and HDR data can be easily merged together in order to provide superior image quality and extended luminance.
XDepth can be built on more efficient image compression technologies such as Jpeg2000. In such case XDepth will maintain compatibility with standard Jpeg2000 files but will enable HDR encoding and compression, exactly like the current version of XDepth for Jpeg-1.