Robert D Feinman

Finding "Invisible" Detail

Sometimes important details of an image are hard to see.
This picture shows the "Tribute in Light" for the World Trade Center as seen from South Street which is on the opposite side of Manhattan Island. Keeping the exposure short enough not to overexpose the buildings in the foreground has made the light very dim. In addition the scattered light from the city lights makes the contrast lower.

Color Original
Color Original

We use the color range selection tool to pick out the very dark color of just the beam of light. By carefully selecting the spot in the image and adjusting the Fuzziness it is possible to extract much of the beam. After the selection has been made it is further possible to clean up the selection by painting on the mask. We chose not to do this since the grainy appearance of the selection is similar to what was seen. The smoke and dust in the air made the beam slightly wispy.

Color Range
Color Range

The trick now is to apply a very severe curve to only the selection. Since the difference in brightness is very slight we need to emphasize this greatly by this steep curve. Because only a small part of the image is selected we do not alter any other areas.
This curve can be applied as a layer or to the image itself.

Curve Dialog

Here is the image with the curve layer applied. Notice that the beam is now quite visible. It appears pretty much as it  did to the naked eye when the picture was taken.

After Curve
After Curve Applied

We're still not satisfied. The image was taken with an extreme wide angle lens and the camera was pointed up to capture as much of the beam as possible. This led to "leaning building" syndrome. We correct most of this with the perspective transformation. A little inward tilt was left in to make the image somewhat more dynamic.

Fix Perspective
Perspective Corrected

Finally we apply another curve layer to remove some of the green caused by the high-intensity street lighting.

Click here for other images from the Tribute of Light.

Final Image
Final Image

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© 2002 Robert D Feinman