Low Level: Image formats in different industries

[Diego Sánchez]

Hi all,

  Besides the ubiquitous single plane color + optional alpha, there are other image formats used by different industries. I'm trying to gather a list of use cases. The ones that come to mind are:

• Stereo pair. Just two image planes, one for each eye.
• Multichannel images, as used in 3D rendering. Sometimes the number of channels is known at compile time, but usually it's defined at runtime.
• Multiple planes, as used in medical imaging. These can have hundreds of planes; so should be considered 3D images, composed of voxels instead of pixels.
• Differently sized planes, as used by video and jpeg compression. Sometimes an image consists of one lightness and two colour planes, where the colour planes have half the vertical and horizontal resolution of the lightness one.
• Different number of channels per pixel. I've found a reference to this in the description of the OpenEXR format, but don't really know anything about it.

  I know a generic solution that covers all known cases is impossible, but knowing what's out there may help define common use patterns and shape the common grounds.

[larry...@gmail.com]

Regarding OpenEXR... it can have any number of channels, but it's the same number of channels for all pixels. Though perhaps you are referring to "deep" images, in which there are multiple *samples* per pixel, each one with a different depth value, used to describe how a value like alpha varies with distance along the ray represented by the pixel. This is a thorny and very specialized issue in the field it comes from (visual effects), way way way out of the scope of anything you'd want in std.