JPEG-2000: Can I dynamically resize an image without resampling?

Question

One of the nice features of JPEG 2000 is that it's easy to downres an image -- just feed out fewer bytes.

Is there a similar way to scale the image, such that I could send a thumbnail using bytes in the full-size file, without resampling?

Answer 1

No, to resize you will still have to read the original size, resample to the new size, and then recompress.

You can write your file such that it has layers with powers-of-2 sizes, with a very small relative incremental increase in size, and extract those layers.