SS YAN M ie hn TP Y A E buo, LR Wu DAE RO M e uf LA ade Den MG YA ON uta md e nr dt zoe a PA yd diera VER MERC: 
rtr DAS IFR SE NILUM D ITE IBS ER MA QUE de LUE ROSES ARR Ss BST MOSS SITE 
The object contrast is defined by: 
Imax - lmin 
C = 
Imax * lmin 
The pictures were recorded at a height of 1050 m and enlarged 
15 times. It was found from different comparisons that the MTF 
halfway between zero and the limiting spatial frequency is 
significant for judging the visual impression of the image. 
This could mean that the MTF for appropriately selected spatial 
frequencies could also be chosen to derive image quality criteria 
similar to those described. The requirement of regularity over 
the field remains. 
Conclusions 
An image quality criterion based on MTF is highly desirable. The 
quality specification should be appropriate for the application 
of the optical system and simple for the user. The proposed quality 
criteria look promising and comparisons with subjective image qua- | 
lity techniques commonly used are favourable. Further evaluations 
are needed before quality specification can be recommended.