CE OD - Contrast Enhancement - adjust Optical Densities
(07/11/97)
- PURPOSE
- Finds the logarithmic transformation (applied to pixels) which
adjusts the histogram of the image file to the normal N(0,1)
distribution. Can be used to convert transmission values
from a scanner to optical density - the assumption is that
pixel values should have normal distributions.
- SEE ALSO
| CE FIT | [Contrast Enhancement - FIT the histogram] |
| CE GNC | [Contrast Enhancement - Graduated Non Convex restoration] |
- USAGE
- .OPERATION: CE OD,X21,X22,X23
- .IMAGE TO CORRECT FILE: IMG001
[Enter the name of the image file which histogram has
to be corrected.]
.HISTOGRAM LENGTH: 16
[Enter the length of the histogram. For 8 bits scanner
the density range is 0-255, thus 16 is appropriate.
For 8 bits scanner use 32.]
NOTES
- Input file can be either 2D or 3D.
- The input file should contain the background noise of
the micrograph.
- The transformation is A*(ALOG10(x+B)+C).
The parameters are returned in the registers:
A - X21
B - X22
C - X23
- Memory requirements: input file is kept in the memory.
- Implemented by Paul Penczek.
- Example is included at the end.
- SUBROUTINES
- HISTOD, HISTODC, FHODT
- CALLER
- UTIL2
; Adjust optical densities to the normal distribution.
CE OD,x21,x22,x23
pap001
32
ar
pap001
_2
x21*(LOG(p1+x22)+x23)
FS
_2
CP
_2
pap002
EN D
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