® Although RMS value changes with the type 
of film used, it mainly depends on the film 
emulsion structure. The RMS of black- 
white negatives is directly proportional to 
density in linearity . The higher the density 
is, the larger the RMS. Additionally, the 
conditions of development have a key 
influence upon RMS value. There are little 
differences in their RMS-D curves for the 
negatives, which are the same type of film, 
the same development condition, but with 
different exposure. 
® Acutance is directly proportional to the 
density difference corresponding to the A 
and B of edge curves, and is inversely 
proportional to the square of the spread 
width of the edge curve. For a given object, 
when the contrast is enhanced. the edge will 
be sharper. 
® The relation between resolution and density 
is as follows: 
(1) Resolution R will be degraded when density 
is too low or too high. The high density makes 
the resolution degrade faster than the low one. 
Therefore, the R value depends mainly on 
whether the exposure or the development is 
controlled properly. 
(2) The optimal density valve D, corresponding 
to the upper limit of resolution Rmax differs from 
the type of film. It generally locates on the left 
part of middle of curve's linear section. 
(3)The optimal density range is of corresponding 
to 0.8Rmax- The image which density range 
exceeds the optimal one is hard to distinguish. 
Tab.1 The quality indices of some aerial negatives 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
type of 
No. film D, AD |MTFS| .R A RMS C visual |exposure| develop | subject 
29 047 |087 | 18 | 46 | 223 | 16 | 268 | Q | nom | under | plain 
30 029 [052| 27 | 46 | 252 | 16 | 169 | UNQ | nom | under | hilly 
31 102|145[090| 24 | 43 [209 | 27 | 148| Q | ov | under | plain 
p 
32 1.48 | 0.69 | 16 | 43 | 209 | 27 |148| Q | se | under |. city 
33 1.23 | 096 [24 |. 43 1.209 | 27.].234 |. Q..], ev. |. ander |, hiliy 
34 078 | 132 | 27 | so | 457 | 9 |600] E | vom | nom | plan 
35...134121 0.8 :| 1.00 20 50 457 9 5.47 E norm | norm |mountain 
36 0.33 [0.58 | 23 | 43 | 486 | 7. | 344 | UNQ | wer | nom | plain 
37 0.31 0.42 22 43 486 7 296 | U NQ under nom |mountain 
38 177 [077] 24 [ 41 [223 | 12 | 2.70 |UNQ| ve [| nom | plain 
39 1.55 |,1.09 23 41 223 12 3.49 | UNQ | over norm |mountain 
25 |3414| 091 | 075 | 30 | 57 | 224 | 10 | 5.20 |GOOD| nom | mom | plain 
26 1.00 | 136 29 56 265 10 |.649 |GOOD| norm | norm [mountain 
27 13412] 055 [087 | 32 | 55 | 148 | 10 | 484 | Q | mem | under | plain 
note camera: LMK; photographic scale: 1:10 000; Q: qualified; UNQ: unqualified 
  
  
Appendices to Tab.1: The average density D, and the image contrast AD are calculated by the histogram 
method; MTFS is the area surrounded by the MTF curve and coordinate axes; R is the image resolution 
calculated in MTF measurements; A is the acutance (10°); RMS is the RMS granularity corresponding to 
the average density D,; C is the information capacity which is calculated with the following formula: 
C-Nlog; M 
N-800R7/eni? 
M=int(10*°AD/2 y2k *R*RMS+1)  k-1.5 
® The Information capacity of aerial negatives 
is directly proportional to contrast and 
112 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996 
  
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