Landsat 8 Dark Object Examples
The images below show points centered on Landsat 8 pixels that have very low relative values in the blue, green, and red bands for entire Landsat 8 scenes, and are essentially dark objects. (Google Earth background imagery is shown, as opposed to the Landsat imagery, in order to have a high resolution view of surface.) The amount of total nonzero values is the amount of pixels with nonzero values and can change a relatively small amount from scene to scene; the amount of different values can change relatively more.
4/17/13: not in shadow in Landsat image
Blue DN value is 8,090; 38,790,925 of the total 38,790,944 nonzero pixels have higher value; 14th lowest value out of 16,582 different values. Green DN value is 6,824; 38,792,060 of the total 38,792,061 nonzero pixels have higher value; the lowest value out of 17,942 different values. Red DN value is 6,214; 38,791,779 of the total 38,791,785 nonzero pixels have higher value; 6th lowest value out of 19,796 different values.
6/20/13: in cloud shadow in Landsat image
Blue DN value is 8,231; 38,778,443 of the total 38,778,466 nonzero pixels have higher value; 15th lowest value out of 23,107 different values. Green DN value is 7,035; 38,779,506 of the total 38,779,532 nonzero pixels have higher value; 20th lowest value out of 24,768 different values. Red DN value is 6,120; 38,779,252 of the total 38,779,272 nonzero pixels have higher value; 12th lowest value out of 27,258 different values.
7/18/13: in cloud shadow in Landsat image
Blue DN value is 8,040; 41,634,923 of the total 41,634,931 nonzero pixels have higher value; 7th lowest value out of 52,089 different values. Green DN value is 6,914; 41,636,179 of the total 41,636,182 nonzero pixels have higher value; 3rd lowest value out of 52938 different values. Red DN value is 6137; 41,635,866 of the total 41,635,891 nonzero pixels have higher value; 16th lowest value out of 55,686 different values.
8/23/13: in cloud shadow in Landsat image
Blue DN value is 8,014; 41,657,020 of the total 41,657,031 nonzero pixels have higher value; 11th lowest value out of 38,579 different values. Green DN value is 6,780; 41,658,217 of the total 41,658,218 nonzero pixels have higher value; the lowest value out of 40,001 different values. Red DN value is 6,013; 41,657,900 of the total 41,657,920 nonzero pixels have higher value; 19th lowest value out of 43,269 different values.
Reference
Chavez, P.S., Jr. 1988. An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data. Remote Sensing of Environment 24: pp.459-479.