Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Kayencee on June 23, 2011, 08:04:23 am

Title: Images with low dynamic range or sparse histograms
Post by: Kayencee on June 23, 2011, 08:04:23 am

Hi,

I am looking for real image databases with either low dynamic range or with a sparse histogram.
Can someone please provide some help.

Thanks.
Kayencee.

Title: Re: Images with low dynamic range or sparse histograms
Post by: feppe on June 23, 2011, 08:10:36 am

It's unclear what exactly you mean by "real image database," "low dynamic range" or "sparse histogram," but this (http://www.flickr.com/groups/lowdynamicrange/) should get you started.

Title: Re: Images with low dynamic range or sparse histograms
Post by: Kayencee on June 23, 2011, 09:50:06 am

Thanks for the link.

By dynamic range, I meant the range of intensities in the image, i.e., the difference of the maximum and minimum intensity (e.g., its 255 for an 8-bit image).
By spare histogram (for example for an 8-bit image) I meant that the image takes on only a few intensity values in the range [0,255].


Kayencee.

Title: Re: Images with low dynamic range or sparse histograms
Post by: stpf8 on June 25, 2011, 09:12:09 pm

I don't have a source, but I have observed that these images are often difficult to work with in the digital darkroom, simply because we too often want to have a full range of tonal values in the image.  That's very easy to accomplish with "levels" in PS, but the result usually does not match what our eyes saw.  One of the biggest challenges when looking at the monitor is trying to remember just what that scene looked like a few days, weeks, or months previously when we opened the shutter.

Title: Re: Images with low dynamic range or sparse histograms
Post by: Guillermo Luijk on June 27, 2011, 07:14:46 pm

Low dynamic range scene, and sparse image histogram:

(http://www.guillermoluijk.com/article/histogram/niebla.jpg) . (http://www.guillermoluijk.com/article/histogram/niebla.gif)

Regards

Title: Re: Images with low dynamic range or sparse histograms
Post by: John MacLean on June 28, 2011, 09:11:05 pm

Lightroom Before & After album (https://www.facebook.com/media/set/?set=a.145690492114992.28367.145239152160126)

Check out the first 3 images in this album. 1st is RAW from camera, 2nd is my processing, and 3rd is the 2 histograms in LR3.