Radiographic projection of objects

Step wedge

Darkening curve of films

exposition

darkening

linear part

darkening

dark bright

human eyes

Rtg. film

Sensitivity to grey spectrumof the eyes and radiographic films

Hermann grid illusion

Mach Band effect

Koffka ring

Koffka ring

Role of the background

Mach Band

Mach Band

Mach Band

Mach Band

Mach Band

Mach Band

Localization of defects

Role of the background

Projection of bone lesions

Projection of bone lesions

Localization of root apex

Apical transparenties

Apical transparenties

Apical transparenties

Apical transparenties

„God is good to endodontists”

• 90% of apical defects transparent

• Mainly localised at the apex

• Close to the cortical bone

• Background usualy bright

Disturbing factors

• Inclination

• Anatomic noise (anatomical landmarks)

• Size (too small)

• Expozition

• Film development

Anatomical landmarks/direction

Facts affect to image quality

sharpness

contrast

projection

projection

brightness-darkness

Projection of periodontium

Periodontium

Projection in the horizontal plain

mesial

distal

orthoradial

Buccal object rule

Same Lingual Opposite Buccal

Parallaxis

Lokalized CT (CBCT)