Sharp IV-C35M User Manual page 95

(2) Gray level change
To change the gray level, you can change the
"**.*TIMES" (magnification by N processing), the
" γ +," " γ -" ( γ (positive/negative) correction), the
"CHNG-L" (widening histogram), and the "INCRS-
M" (mid emphasis) functions.
Gray level change
Magnification by N
processing
(**.* TIMES)
γ
(positive/negative)
correction
Histogram
widening
Mid emphasis
To improve the contrast (the ratio of high value gray levels to low value gray
levels), specify a magnification rate (00.0 to 99.9) for multiplying the image
data.
- If the magnified gray level exceeds 255, the system will correct the value
to 255.
Use to correct mid gray level.
- γ positive correction: used when the mid gray level is too low.
255
Input image gray level
- γ negative correction: used when the mid gray level is too high.
255
Input image gray level
This is a method to widen the histogram of an image in which the histogram
is at part of it, thus improve its contrast.
a
b
0 Gray level
1 Bad contrast image
Emphasize the mid gray level.
- This improves contrast while remaining the background image.
- The input image density (G) can be converted to the output image density
with the following formulas:
Input image gray level(G)
0 to 127
128 to 255
3-33
Setting the Conditions for Each Object Type
IMG PRE-PROC SCREEN COND SAVE
1COMPARE IMGS
NO
2CHNG GRAY LEVEL
NO
NO
CONTRAST MAGNI
g+
3SPACE FILTER
NO
g-
CHNG-L
INCRS-M
Details
255
255
m m
Z 0 Z
Gray level
2 Good contrast image
Output image gray level
RED F C1 BRT
3