Defect Depth or Total Deviation (numerals)

Hotkey: D
Menu: Image > Defect depth / Total Deviation
Context menu: Defect depth / Total Deviation

This image shows the Total Deviation (Defect depth) as number. The values are typically in the range of +5 dB through –35 dB. Negative numbers are "defects", positive numbers are supernormal values.

The numbers are color coded. The colors correspond to the Color Defect Map

calculation impossible (normal value < 0 dB or missing)

symbol of an absolute defect (brightest stimulus not seen)

symbol of a value between +4 dB and -4 dB ("normal range")

this button switches off the symbol representation (all numbers are shown)


Defect depth or total deviation are norm-related values. A normal value has 0 dB   -- Click here for more information about this value type, the meaning and interpretation


CONCLUSION: This image type makes defects visible. The numbers are giving detailed information about the depth in decibel. The importance of isolated defects can be understood exactly. The mental assessment of all 50 through 100 numbers is practically impossible. Therefore, the Color Defect Map (CDM) should be consulted in addition. The CDM Plus with the numerical overlay combines both images.


Further information

Defects are usually negative. The sign can be inverted: Menu Extra > Options > Tab Display > Defect value sign (+)

For a better recognition of the blind spot, normal values in this area are taken from the surrounding. The blind spot appears as a deep defect. These pseudo-values are excluded in statistical calculations (indices)

Small differences between the defect depth in PeriData and the instrument's printout are possible because of rounding differences