{"id":840,"date":"2008-06-18T19:21:18","date_gmt":"2008-06-18T10:21:18","guid":{"rendered":"https:\/\/regex.info\/blog\/2008-06-18\/840"},"modified":"2013-08-28T14:01:25","modified_gmt":"2013-08-28T05:01:25","slug":"hdr-and-why-i-dont-do-it","status":"publish","type":"post","link":"https:\/\/regex.info\/blog\/2008-06-18\/840","title":{"rendered":"“HDR”, and Why I Don’t Do It"},"content":{"rendered":"\n\n

High-dynamic-range<\/i> – HDR<\/b> – is an\nimage-processing technique that's been gaining popularity over the last few\nyears. HDR can be<\/span> used to create some amazing, impactful, stunning<\/i>\nimages. For some eye<\/span>-popping examples, see this page<\/a>, which\nis just one page of many that are linked from this HDR\nroundup<\/a>.<\/p>\n\n

I haven't created anything amazing with HDR, but I utilized<\/span> HDR in\nwhipping this image together, just for this post...<\/p>\n\n

<\/a>\nNikon D200 + Nikkor 17-55\/2.8 @ 34 mm — HDR, f<\/span>\/3.5 —\nmap & image data<\/a> — nearby photos<\/a><\/span><\/span>\nHDR Example<\/span>\nboring, but illustrative\n<\/div>\n\n

HDR attempts to overcome a limitation of current camera technology... a\nlimitation<\/span> that disallows a camera<\/span> from picking up fine detail in the dark\nshadows and<\/i> bright highlights of a scene<\/span> at the same time. This\nlimitation can be easily seen in the main source photo used in creating\nthe image above, a two<\/span>-second exposure that I took<\/span> during the Kyoto Higashiyama “Hanatoro”\nLightup Event<\/a> in March:<\/p>\n\n

\nNikon D200 + Nikkor 17-55\/2.8 @ 34 mm — 2 sec<\/span>, f<\/span>\/3.5, ISO 100 —\nmap & image data<\/a> — nearby photos<\/a><\/span><\/span>\nOriginal Photo<\/span>\nExposed to bring out detail in the street and other darker areas,\nwith the unfortunate side effect that the lanterns are “blown out”\n<\/div>\n\n

As you can see here, the lanterns appear<\/i> to be just big blobs of\nwhite. They weren't big blobs of white, of course (they were a delicate<\/span>\npattern of fine colors, and looked like this<\/a>),\nbut with the limitations of my camera's image sensor, if I left<\/span> the shutter\nopen long enough for a reasonable<\/span> capture of the dark street, the relative\nfirehose of photons from the much brighter lanterns simply overwhelm the\nsensor in that part of the photo. With my camera's sensor, as with\nvirtually all digital cameras today, “overwhelm” means “registers as pure\nwhite.”<\/p>\n\n

On the other hand, if I use a shorter exposure – one that slams\nthe door shut on the photon firehose before the image of the lanterns is\ntotally blown out – the detail in the lanterns is retained, but now\nthe unfortunate side effect is that the dark areas of the scene don't have a\nchance<\/span> to send enough photons, and they end up black. Here's the same\nscene, but with a much<\/span> shorter exposure that allowed only 1.7% as much\nlight in as above...<\/p>\n\n

\nNikon D200 + Nikkor 17-55\/2.8 @ 34 mm — 1<\/sup>\/<\/big>30 sec<\/span>, f<\/span>\/3.5, ISO 100 —\nmap & image data<\/a> — nearby photos<\/a><\/span><\/span>\nShorter Exposure<\/span>\nDetail now mostly retained in the lanterns, but lost everywhere else\n<\/div>\n\n

In this particular situation, my eyes didn't have a problem<\/span> capturing\ndetail in all areas of the scene at once, but like our cameras, our eyes do\nsuffer from this issue to some extent (try reading the label on the end of\na 100w<\/span> bulb while it's lit and you'll have a difficult<\/span> time of it). Still,\ncamera technology is far behind God in this respect, and that's where HDR\ncomes in.<\/p>\n\n

To create the shot seen at the top of this post, I brought<\/span> in lantern\ndetail from the “shorter exposure” image, as well as from another\nintermediate image, and blended it all in where the original was blown out. For having<\/span> spent just a few<\/span> minutes on it (and without much HDR experience\nto begin with), the technical result in this case is surprisingly good\n– the result looks completely natural – although the effort\nseems to be a waste<\/span> of energy on such a boring<\/span> scene.<\/p>\n\n

Here again is the HDR version, and the three photos used to make it;\nmouseover the buttons below the image to see each version...<\/p>\n\n

\n\n
<\/a>\n Nikon D200 + Nikkor 17-55\/2.8 @ 34 mm — HDR, f<\/span>\/3.5<\/span>\n <\/div>\n\n
\n HDR Result<\/span>\n   –  \n Original Photo<\/span>\n  · \n Mid<\/span>\n  · \n Highlight Detail<\/span>\n <\/div>\n mouseover button to see that image\n\n\n\n