Blue skies contains 20 HDRIs of neutral, blue skies.
High Dynamic Range Images (HDRI for short) allow you to import the complex lighting of a real scene in your individual 3D-design. Perfect shadow casting and reflection propel renderings into a new dimension of realism and expressiveness.
The resolution of the Spherical Map HDRIs is 10,996 x 5,498 pixel. Additionally, the HDRIs are provided as Lightprobes (4096×4096), Horizontal Cross(8192×6144) and Vertical Cross (6144×8192).
Radiosity – and therefore the use of HDRIs is directly supported in many 3D-applications like Lightwave (version 6.0 and higher), Softimage|XSI, Maya & Mentalray, Pixar RenderMan, Bryce 6, Autodesk VIZ, messiah:render (Arnold), InSight (Integra), 3ds-max & VRay, 3ds-max & Brazil r/s (Splutterfish), 3ds-max & finalRender (Cebas), Cinema4D Version 8.1 and more. For further HDRI-rendering tools options the documentation of the used 3D-program should be consulted.
And each HDR image is provided in the industry standard .HDR. So they are useable in most rendering applications.