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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.

SEE ALSO

CE [Contrast enhancement]
CE FIT [Contrast Enhancement - fit the histogram]
CE GNC [Contrast enhancement - graduated non convex restoration]
CE MED [Contrast enhancement - using median filtering]

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 other numbers of bits histogram length has to be changed.]

NOTES

  1. Input file can be either 2D or 3D.

  2. The input file should contain the background noise of the micrograph.

  3. The transformation is A*(ALOG10(x+B)+C).
    The parameters are returned in the registers:
    A - X21
    B - X22
    C - X23

  4. Memory requirements: input file is kept in the memory.

  5. Implemented by Paul Penczek.

  6. EXAMPLE:
     
     ; Adjust optical densities to the normal distribution. 
     CE OD,x21,x22,x23 
     pap001 
     16 
     ar 
     pap001 
     _1 
     LOG((p1+x22)*1) 
     ar 
     _1 
     _2 
     ((p1+x23)*x21) 
     FS 
     _2 
     CP 
     _2 
     pap002 
     EN D 
    


SUBROUTINE: HISTOD, HISTODC, FHODT

CALLER:     UTIL2




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