Alien Anomalies

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Post Info TOPIC: Areas of Pure Black in Images


Teaching the truth

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Areas of Pure Black in Images
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I just thought I would remind everyone that the images at the official Mars Rover website (http://marsrovers.jpl.nasa.gov/) have been 'enhanced' to reduce the range of greys. Or.. to put it another way, the images in the pds repository have been stretched to allow a fuller range of greys. See below.

This means that images from the Mars Rover site will often have shadow areas of pure black, where nothing is visible and nothing ever will be visible in those areas - however much manipulation is done to the image.

Let me give an example of 1P317898595EFFAB00P2366L5M1.JPG 

The image on the left is the original, the image in the middle is stretched over the whole range of greys(which is still unable to show anything in the pure black areas), the image on the right is the one showing areas of pure black(0,0,0) which are shown marked red.

However, if you use the one from the pds it has a fuller range of greys and so there is more opportunity to enhance the darker areas.

If you are unsure, a program to show the pure black areas in an image is available, go to the first link in my signature.



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