Retinex Image Processing





To view these images on a computer monitor as their creators intended them to be seen, the monitor should be calibrated to some standard. Unfortunately, there are no set standards for monitor calibration in the personal computer world. The best that can usually be done is to adjust the brightness and contrast controls to view the full tonal range of the image. For best viewing of these images, adjust your monitor to the grayscale below per the instructions. These images are optimized for viewing at 24-bit color

Adjust the brightness and contrast of your monitor so that you can see each step separately. Pay more attention to the black steps. The darkest step should be as dark as you can make it while still being able to distinguish it from the next lighter step.

Extending your browser window to full width should make the following images line up as pairs. Click on each image to download the full resolution image (1200X1300 ~1-3MB each).













Original image With NASA Technology

These first 5 images were taken outdoors in strong sunlight. Capturing detail in sunlit areas as well as shadow areas is always a challenge. In the processed images it appears as if fill flash was used. 1 2 3 4 5 Indoor with flash and mixed lighting. Note the increased sharpness. This photo was taken with a soft focus filter attached to the lens. 6 Indoor with tungsten flood lights and heavy light falloff. The processed image brings out much detail that was otherwise lost and makes colors more realistic. 7 In this image, detail inside the cockpit is lost due to hazing from the canopy reflections. Processing dramatically brings it out. 8 Another example of strong sunlight and dark shadows. 9 Note the detail outside the window that is retained while that which is inside is greatly enhanced. 10 Overcast skies with diffuse lighting. Color and contrast are subdued in the original images but revealed in the processed ones. 11 Dark original caused by shooting into the sun. Processing brings out detail and color in the shadows. Note the dirty knees. 14 Darkened scene from heavy tree canopy with strong sunlight leaking through, creating strong contrast. Note reflection in window. 15 Very high contrast in original. Dark, tinted window on truck holds much detail brought out only after processing. 16 Dark subject gets lost against its own shadow with on-camera flash. Processing makes subject stand out and reveals tremendous color and detail. 17 Sunlit subject. Processing brings out color and detail not even noticed before. 18 This image is not that impressive until one realizes tht this was taken on the shadow side of this vehicle. 19 Wonderful example of large room with troublesome light falloff from sunlight outside mixed with tungsten light from inside. Flash would have only made this image worse by increasing the light in the foreground only. 20 Original X-ray mammogram is almost featureless before processing. Note date at the bottom which was not even visible in the original. 21 Originals taken in strong sunlight with loss of color and detail in the shadows. Note detail in white areas that are retained and presence of blue car in foreground. 22 23 24 Hazy, low contrast images taken through thick smoke. Processing brings out dramatic detail that was not even visible to the observer. 25 26 Very typical image take from Earth orbit. Many low contrast and dark areas. Spectacular detail is revealed after processing. Note extent of sediment outwash. 27

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