Localized Contrast Enhancement — Detailed Results
Data Used
The cuneiform tablet is item "Spalding 1, Ur III", on loan from Gordon Young. The input data was obtained by simply scanning the tablet on a flatbed document scanner at 600 dpi. Thumbnails of the original unenhanced scans are:
| Obverse face | Reverse face |
| 1st row | 1st row (over top edge) |
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| 2nd row | 2nd row |
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| 3rd row | 3nd row |
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| 4th row | 4th and 5th row |
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| 5th row | |
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The 600 dpi resolution results in the following dimensions of the regions considered when remapping each pixel:
| Radius | Area | ||||
| pixels | inches | mm | pixels2 | inches2 | mm2 |
| 100 | 0.1667 | 4.2333 | 31415 | 0.08727 | 56.3008 |
| 50 | 0.08333 | 2.1167 | 7853 | 0.02182 | 14.0752 |
| 25 | 0.04167 | 1.0583 | 1963 | 0.005454 | 3.5188 |
| 12 | 0.02 | 0.508 | 452 | 0.001257 | 0.8107 |
Format of data presentation
Each initial image will be analyzed in turn. The images will show:
- Initial image
- Global histogram equalization
- Localized histogram equalization, radius of 100 pixels
- Localized histogram equalization, radius of 50 pixels
- Localized histogram equalization, radius of 25 pixels
- Localized histogram equalization, radius of 12 pixels
The images shown here are actually downsampled 50%x50% from the originals to reduce the size of this page from 26 MB to 8.3 MB! As an added benefit, it does allow you to compare results from three or four radii (assuming you have a 1024x768 display).
Cuneiform tablet, Spalding 1, Ur III, obverse face, 1st row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, obverse face, 2nd row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, obverse face, 3rd row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, obverse face, 4th row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, obverse face, 5th row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, reverse face, 1st row (over top)
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, reverse face, 2nd row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, reverse face, 3rd row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, reverse face, 4th and 5th row
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, obverse face, rotated 30 degrees toward edge
Note that this image has been rotated 90 degrees for viewing
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, reverse face, rotated 45 degrees toward edge
Note that this image has been rotated 90 degrees for viewing
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
Cuneiform tablet, Spalding 1, Ur III, edge
Note that this image has been rotated 90 degrees for viewing
Original image
Global histogram equalization
Localized histogram equalization, radius = 100
Localized histogram equalization, radius = 50
Localized histogram equalization, radius = 25
Localized histogram equalization, radius = 12
