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How Lucis Works

In this tutorial will be talking about how the patented Lucis Pro algorithm works, and in particular how the enhance detail slider enhances image detail. Understanding how Lucis works will help you use Lucis more effectively.

What you see below is the Lucis Pro 6.0 user interface. The image in the preview window is an 8-bit grayscale digital image of a canceled stamp. (Click here or on the image below to download the image of a cancelled stamp (2 MB tiff image).) Across the stamp a thick black smear was drawn using a black marker. I am using a grayscale image for this example because Lucis works on intensity information only. How color images are processed is covered in a different Usage Tip.

The Enhance Detail slider value shows you how many intensity levels are in the image. In this case we are using almost the full range of intensity levels, 255 out of a possible 257. (An 8-bit image has 256 intensity levels but since the lowest level for the Smooth Detail slider is 1 not zero, the highest level is 256 plus 1 or 257) This image contains a great deal of information that we can’t see. Our eyes can differentiable approximately 32 levels on contrast. A contrast difference has to be large enough or we can’t see it. Small contrast variances are either seen as unresolved texture or no difference is perceived at all.

In this image of the cancelled stamp the black pixels created by the black marker drawn over black image details are slightly darker than black pixels created from black marker drawn over gray areas and black marker over white areas.

Lucis enables us to accurately see the smallest contrast variances (image detail) simultaneously in the bright, dark, and mid- range areas. Lucis is based on a patented algorithm called Differential Hysteresis Processing. Lucis maps out contrast variances by comparing the intensity of each pixel with every other pixel along hundreds of radial lines called scan lines. (16 scan lines equals 1 Scan Line.) Using the simple Lucis controls (sliders) you choose a range of contrast variances that you would like to see more clearly. Contrast variances within the range are enhanced and contrast variances outside the range are diminished. Lucis is shifting the relative emphasis of contrast variances. Lucis is not throwing away information. Because Lucis is analyzing relative contrasts, detail is simultaneously and accurately revealed throughout the image.

Lucis is enhancing contrast variances that are less than or equal to the Enhance Detail slider value. With this example as we move the Enhance Detail slider to the left detail emerges. So with Enhance Detail slider at 53 (image below), contrast variances less than or equal to 53 intensity levels in magnitude are being enhanced and contrast variances greater than 53 intensity levels are being diminished. We can start to see the parts of the image underneath the black mark. Click here or on the image below to download the image Lucis-processed with the Enhance Detail slider set to 53.

As you move the Enhance detail slider further to the left more detail emerges and the image becomes flatter. With the Enhance Detail slider at 23 you can start to see the text underneath the black mark. Also all of the small contrast variances in the bright areas are also being enhanced. Click here or on the image below to download the image Lucis-processed with the Enhance Detail slider set to 23.

The Enhance Detail slider can be set to as low as 3, meaning that contrast variances 3 intensity levels or smaller are able to be viewed. Moving the Enhance Detail slider back and forth is a great way to explore your image. Click here or on the image below to download the image Lucis-processed with the Enhance Detail slider set to 3.

This next image is a test image developed by Professor Brian Matsumoto, University of California, Santa Barbara. (Click here to download this image (644 KB jpg image)). Professor Matsumoto created an 8-bit grayscale test pattern with differing lines and shaded areas. This 8-bit test pattern uses the full range of intensity levels, namely 257. He replicated this test pattern in the top right and bottom left corners of this test image. Then he mapped this test pattern to the smallest 16 intensity levels and placed this modified test pattern in the bottom right part of the test image. Finally Professor Matsumoto mapped the test pattern to the brightest 24 intensity levels and placed this modified test pattern in the top left quadrant of the test image. So the white and black portions of this image have pixels whose contrasts vary by 16 intensity levels or less. We cannot see very much detail even though a great deal of detail is present. Click here or on the image below to download this test image (644 KB jpg).

By moving the Enhance Detail slider to the left we can enhance the detail everywhere in this image.  With the Enhance Detail slider set to 89 we are starting to see detail in the top left and bottom right portions of the image because contrast variances less than or equal to 89 intensity levels are being enhanced, and those portions of the image have intensity variation of 16 intensity levels or less. So we can start to see those details. Click here or on the image below to download the test image lucis-processed with the Enhance Detail slider set to 89 (876 KB tiff).

With the Enhance Detail slider set to 35 we can see even more image information. Click here or on the image below to download the test image Lucis-processed with the Enhance Detail slider set to 35 (1 MB tiff).

Finally with the Enhance Detail slider set to 9 we can see everything. The processed image is below. Click here or on the image below to download this Lucis-processed image (1.4 MB jpg).

 

By just copying only the top left quadrant of the test image and looking at the histogram we can see that the contrasts in the top left quadrant of the original test image varied by no more than 24 intensity levels. (Bottom left image.) The histogram of the top left quadrant of the Lucis-processed image with the Enhance Detail slider set to 35 is shown on the right. The range of contrasts in the top left quadrant of Lucis-processed image have been increased to 165 intensity levels.

Below is the histogram of the top left portion of the test image when Lucis-processed with the Enhance Detail slider set to 9. Now the full range of image intensities are being utilized.

 

Similarly we can examine the bottom right quadrant of the test image which was very dark. By just copying the bottom right quadrant of the test image and looking at the histogram we can see that the original image contrasts in that part of the test image varied by no more than 16 intensity levels. (Bottom left image.) The histogram of the bottom right quadrant of the test image Lucis-processed with the Enhance Detail slider set to 35 is shown on the right. The range of contrasts in the Lucis-enhanced bottom right quadrant of the test image have been increased to 141 intensity levels.

Below is the histogram of the bottom right quadrant of the test image when Lucis-processed with the Enhance Detail slider set to 9. Now the full range of image intensities are being used.

So what does this mean for your photographic images? It means that by just using just one slider you can accurately reveal incredible image detail throughout your image. You can explore your image's content. (Hence the company name Image Content Technology.)

The image in the Lucis preview window below is an underexposed image that also has some very bright areas- such as the window, the overhead light and the mirror on the back wall. This image uses the full intensity range for an 8-bit image (257 intensity values). Click here or on the image below to download this image (1.9 MB jpg).

As I move the Enhance Detail slider to the left detail emerges throughout the image. Now you can see that my niece is sitting at a table, you can see the reflection in the mirror and even the view outside the window. Click here or on the image below to download the image Lucis-processed with the Enhance Detail slider set to 21 (5 MB jpg).

This web page only addressed using the Enhance Detail slider in Single Channel mode. Other Usage Tips (currently under development) will address topics such as using the Smooth Detail slider, Scan Lines, Split Channel mode, etc. Please join the e-mail list to be notified when new Usage Tips are posted.