What is High Dynamic Range Image (HDRI)?

By Xah Lee. Date: . Last updated:
New York City at night HDR
A multi-exposure composite image of New York. image source

Note how sometimes in a photo, parts are not detailed. You adjust contrast and brightness, but other parts becomes too bright or fainted out.

The solution, is to take several photos using different exposures, and then combine these photos into one. This technique is called: Tone mapping, High dynamic range image. The result is a colored image with high detail everywhere, which may make the image look artificial, but desirable for its detailed illustrative effect.

the following are 4 images, taken with different exposure. Each one by itself is not great, but capture parts in detail.

St Louis Arch mult expEV-4.72 St Louis Arch mult expEV-1.82 St Louis Arch mult expEVp1.51 St Louis Arch mult expEVp4.09
(Photo by Kevin McCoy)

Combined Image

St Louis Arch mult expCDR
combined image. (Photo by Kevin McCoy)

Combined Image with Tone Mapping

St Louis Arch mult expToneMapped
combined image with tone mapping. (Photo by Kevin McCoy)

Problem: What systematic technique to use to turn the first image into the second image?

Flaming June Frederic Leighton Flaming June Frederic Leighton orig

The first image is from Wikipedia. The second is found on the net. Apparently, someone made the tone better, but also cropped the image, and censored the nipple.

Look at the second image, and note the color of the wall, the girl's skin color, the blue-colored clothing on the right, and how the girl's calf is clearly see-thru.

I'm using GIMP and tried various color filters and adjustments, but couldn't do it after trying the various parameters and filters. The one technique is to select parts and apply color changes, but i'm seeking solutions that apply to the whole image. (unless, a image pro specializing in color enhancing tells me the only solution is to edit parts of the image separately.)

I think a combination of the following will do it: Filters:Colors:Retinex, Layers:Colors:Curves, Filters:Enhance:Unshap Mask.

Note: The picture is Flaming June by Frederic Leighton.

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