File format for mixed resolution?

[johnfi...@gmail.com]

Is there a file format that is better than ordinary formats for the result of combining photos with different resolutions?

I want to combine two photos, where one is a higher resolution image of the most interesting feature in another.  When viewing on a computer, I want to be able to zoom in to the interesting feature and see full detail or zoom out and see full context.

The obvious general approach would over sample the wide photo up to the resolution of the narrow photo, then combine them with a mask to force all but the edges of the inner photo to be used unblended.  That result would have far more pixels than it actually has content, but should be compressible to eliminate most of that waste.  Then a fairly fast computer with large ram could decompress it for viewing.

But is there a better way?  A format that more directly supports multiple resolutions?  Or a container file for multiple photos and a viewer that combines them on the fly.  I assume they would be pre-warped for better alignment and have an alpha channel for on the fly blending, but the resolution difference would be dealt with on the fly, up or (most often) down sampling each separately to the display resolution.

[David W. Jones]

Well, the TIFF format supports having a thumbnail in the file. I think it also supports muliple layers, and definitely supports file compression. I don't know if it supports multiple resolutions, though.

Many graphics viewers already support TIFF files.

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David W. Jones
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