On Wed, Sep 4, 2013 at 2:22 PM, Igor Roshchin <[email protected]> wrote:
> I have a question for John Sessoms: > John, you wrote for your photo: > "This is not an HDR image. It is a blend of 4 exposures 2 sec to 45 sec > using layer masks & blend modes." > How is it different from HDR? I would say that the difference is that in "HDR imaging" (as the term is generally used) at some point (prior to tone-mapping) you produce a scene-referred high-dynamic-range image. This requires understanding or measuring the quantitative exposure relationship between the input LDR images, allowing the software to know (for example) that a bright point in the HDR image is 1,000,000 times brighter in the original scene than a darker point. What John did is more akin to exposure fusion, as performed by the Enfuse software for example (although it sounds like John blended images manually). In exposure fusion, the pixels in the output image are a weighted average of the pixels in the input image (with weights varying from pixel to pixel), but exposure fusion algorithms don't need to know the quantitative relationships between the exposures... they can just prefer to weight pixels that are "well exposed" (i.e. near the middle of the LDR exposure range). -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
